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張 旭

Volumes - Kubernetes - 0 views

kubernetes.io/...volumes

kubernetes volume disk nfs

shared by 張 旭 on 28 May 19 - No Cached
  • On-disk files in a Container are ephemeral,
  • when a Container crashes, kubelet will restart it, but the files will be lost - the Container starts with a clean state
  • In Docker, a volume is simply a directory on disk or in another Container.
  • ...105 more annotations...
  • A Kubernetes volume, on the other hand, has an explicit lifetime - the same as the Pod that encloses it.
  • a volume outlives any Containers that run within the Pod, and data is preserved across Container restarts.
    • 張 旭
      張 旭 on 06 Jul 19
       
      Kubernetes Volume 是跟著 Pod 的生命週期在走
  • Kubernetes supports many types of volumes, and a Pod can use any number of them simultaneously.
  • To use a volume, a Pod specifies what volumes to provide for the Pod (the .spec.volumes field) and where to mount those into Containers (the .spec.containers.volumeMounts field).
  • A process in a container sees a filesystem view composed from their Docker image and volumes.
  • Volumes can not mount onto other volumes or have hard links to other volumes.
  • Each Container in the Pod must independently specify where to mount each volume
  • localnfs
  • cephfs
  • awsElasticBlockStore
  • glusterfs
  • vsphereVolume
  • An awsElasticBlockStore volume mounts an Amazon Web Services (AWS) EBS Volume into your Pod.
  • the contents of an EBS volume are preserved and the volume is merely unmounted.
  • an EBS volume can be pre-populated with data, and that data can be “handed off” between Pods.
  • create an EBS volume using aws ec2 create-volume
  • the nodes on which Pods are running must be AWS EC2 instances
  • EBS only supports a single EC2 instance mounting a volume
  • check that the size and EBS volume type are suitable for your use!
  • A cephfs volume allows an existing CephFS volume to be mounted into your Pod.
  • the contents of a cephfs volume are preserved and the volume is merely unmounted.
    • 張 旭
      張 旭 on 06 Jul 19
       
      相當於自己的 AWS EBS
  • CephFS can be mounted by multiple writers simultaneously.
  • have your own Ceph server running with the share exported
  • configMap
  • The configMap resource provides a way to inject configuration data into Pods
  • When referencing a configMap object, you can simply provide its name in the volume to reference it
  • volumeMounts: - name: config-vol mountPath: /etc/config volumes: - name: config-vol configMap: name: log-config items: - key: log_level path: log_level
  • create a ConfigMap before you can use it.
  • A Container using a ConfigMap as a subPath volume mount will not receive ConfigMap updates.
  • An emptyDir volume is first created when a Pod is assigned to a Node, and exists as long as that Pod is running on that node.
  • When a Pod is removed from a node for any reason, the data in the emptyDir is deleted forever.
  • By default, emptyDir volumes are stored on whatever medium is backing the node - that might be disk or SSD or network storage, depending on your environment.
  • you can set the emptyDir.medium field to "Memory" to tell Kubernetes to mount a tmpfs (RAM-backed filesystem)
  • volumeMounts: - mountPath: /cache name: cache-volume volumes: - name: cache-volume emptyDir: {}
  • An fc volume allows an existing fibre channel volume to be mounted in a Pod.
  • configure FC SAN Zoning to allocate and mask those LUNs (volumes) to the target WWNs beforehand so that Kubernetes hosts can access them.
  • Flocker is an open-source clustered Container data volume manager. It provides management and orchestration of data volumes backed by a variety of storage backends.
  • emptyDir
  • flocker
  • A flocker volume allows a Flocker dataset to be mounted into a Pod
  • have your own Flocker installation running
  • A gcePersistentDisk volume mounts a Google Compute Engine (GCE) Persistent Disk into your Pod.
  • Using a PD on a Pod controlled by a ReplicationController will fail unless the PD is read-only or the replica count is 0 or 1
  • A glusterfs volume allows a Glusterfs (an open source networked filesystem) volume to be mounted into your Pod.
  • have your own GlusterFS installation running
  • A hostPath volume mounts a file or directory from the host node’s filesystem into your Pod.
  • a powerful escape hatch for some applications
  • access to Docker internals; use a hostPath of /var/lib/docker
  • allowing a Pod to specify whether a given hostPath should exist prior to the Pod running, whether it should be created, and what it should exist as
  • specify a type for a hostPath volume
  • the files or directories created on the underlying hosts are only writable by root.
  • hostPath: # directory location on host path: /data # this field is optional type: Directory
  • An iscsi volume allows an existing iSCSI (SCSI over IP) volume to be mounted into your Pod.
  • have your own iSCSI server running
  • A feature of iSCSI is that it can be mounted as read-only by multiple consumers simultaneously.
  • A local volume represents a mounted local storage device such as a disk, partition or directory.
  • Local volumes can only be used as a statically created PersistentVolume.
  • Compared to hostPath volumes, local volumes can be used in a durable and portable manner without manually scheduling Pods to nodes, as the system is aware of the volume’s node constraints by looking at the node affinity on the PersistentVolume.
  • If a node becomes unhealthy, then the local volume will also become inaccessible, and a Pod using it will not be able to run.
  • PersistentVolume spec using a local volume and nodeAffinity
  • PersistentVolume nodeAffinity is required when using local volumes. It enables the Kubernetes scheduler to correctly schedule Pods using local volumes to the correct node.
  • PersistentVolume volumeMode can now be set to “Block” (instead of the default value “Filesystem”) to expose the local volume as a raw block device.
  • When using local volumes, it is recommended to create a StorageClass with volumeBindingMode set to WaitForFirstConsumer
  • An nfs volume allows an existing NFS (Network File System) share to be mounted into your Pod.
  • NFS can be mounted by multiple writers simultaneously.
  • have your own NFS server running with the share exported
  • A persistentVolumeClaim volume is used to mount a PersistentVolume into a Pod.
  • PersistentVolumes are a way for users to “claim” durable storage (such as a GCE PersistentDisk or an iSCSI volume) without knowing the details of the particular cloud environment.
  • A projected volume maps several existing volume sources into the same directory.
  • All sources are required to be in the same namespace as the Pod. For more details, see the all-in-one volume design document.
  • Each projected volume source is listed in the spec under sources
  • A Container using a projected volume source as a subPath volume mount will not receive updates for those volume sources.
  • RBD volumes can only be mounted by a single consumer in read-write mode - no simultaneous writers allowed
  • A secret volume is used to pass sensitive information, such as passwords, to Pods
  • store secrets in the Kubernetes API and mount them as files for use by Pods
  • secret volumes are backed by tmpfs (a RAM-backed filesystem) so they are never written to non-volatile storage.
  • create a secret in the Kubernetes API before you can use it
  • A Container using a Secret as a subPath volume mount will not receive Secret updates.
  • StorageOS runs as a Container within your Kubernetes environment, making local or attached storage accessible from any node within the Kubernetes cluster.
  • Data can be replicated to protect against node failure. Thin provisioning and compression can improve utilization and reduce cost.
  • StorageOS provides block storage to Containers, accessible via a file system.
  • A vsphereVolume is used to mount a vSphere VMDK Volume into your Pod.
  • supports both VMFS and VSAN datastore.
  • create VMDK using one of the following methods before using with Pod.
  • share one volume for multiple uses in a single Pod.
  • The volumeMounts.subPath property can be used to specify a sub-path inside the referenced volume instead of its root.
  • volumeMounts: - name: workdir1 mountPath: /logs subPathExpr: $(POD_NAME)
  • env: - name: POD_NAME valueFrom: fieldRef: apiVersion: v1 fieldPath: metadata.name
  • Use the subPathExpr field to construct subPath directory names from Downward API environment variables
  • enable the VolumeSubpathEnvExpansion feature gate
  • The subPath and subPathExpr properties are mutually exclusive.
  • There is no limit on how much space an emptyDir or hostPath volume can consume, and no isolation between Containers or between Pods.
  • emptyDir and hostPath volumes will be able to request a certain amount of space using a resource specification, and to select the type of media to use, for clusters that have several media types.
  • the Container Storage Interface (CSI) and Flexvolume. They enable storage vendors to create custom storage plugins without adding them to the Kubernetes repository.
  • all volume plugins (like volume types listed above) were “in-tree” meaning they were built, linked, compiled, and shipped with the core Kubernetes binaries and extend the core Kubernetes API.
  • Container Storage Interface (CSI) defines a standard interface for container orchestration systems (like Kubernetes) to expose arbitrary storage systems to their container workloads.
  • Once a CSI compatible volume driver is deployed on a Kubernetes cluster, users may use the csi volume type to attach, mount, etc. the volumes exposed by the CSI driver.
  • The csi volume type does not support direct reference from Pod and may only be referenced in a Pod via a PersistentVolumeClaim object.
  • This feature requires CSIInlineVolume feature gate to be enabled:--feature-gates=CSIInlineVolume=true
  • In-tree plugins that support CSI Migration and have a corresponding CSI driver implemented are listed in the “Types of Volumes” section above.
  • Mount propagation allows for sharing volumes mounted by a Container to other Containers in the same Pod, or even to other Pods on the same node.
  • Mount propagation of a volume is controlled by mountPropagation field in Container.volumeMounts.
  • HostToContainer - This volume mount will receive all subsequent mounts that are mounted to this volume or any of its subdirectories.
  • Bidirectional - This volume mount behaves the same the HostToContainer mount. In addition, all volume mounts created by the Container will be propagated back to the host and to all Containers of all Pods that use the same volume.
  • Edit your Docker’s systemd service file. Set MountFlags as follows:MountFlags=shared
張 旭

Secrets - Kubernetes - 0 views

kubernetes.io/...secret

kubernetes secret password security

shared by 張 旭 on 05 Jul 19 - No Cached
  • Putting this information in a secret is safer and more flexible than putting it verbatim in a PodThe smallest and simplest Kubernetes object. A Pod represents a set of running containers on your cluster. definition or in a container imageStored instance of a container that holds a set of software needed to run an application. .
  • A Secret is an object that contains a small amount of sensitive data such as a password, a token, or a key.
  • Users can create secrets, and the system also creates some secrets.
  • ...63 more annotations...
  • To use a secret, a pod needs to reference the secret.
  • A secret can be used with a pod in two ways: as files in a volumeA directory containing data, accessible to the containers in a pod. mounted on one or more of its containers, or used by kubelet when pulling images for the pod.
  • --from-file
  • You can also create a Secret in a file first, in json or yaml format, and then create that object.
  • The Secret contains two maps: data and stringData.
  • The data field is used to store arbitrary data, encoded using base64.
  • Kubernetes automatically creates secrets which contain credentials for accessing the API and it automatically modifies your pods to use this type of secret.
  • kubectl get and kubectl describe avoid showing the contents of a secret by default.
  • stringData field is provided for convenience, and allows you to provide secret data as unencoded strings.
  • where you are deploying an application that uses a Secret to store a configuration file, and you want to populate parts of that configuration file during your deployment process.
  • a field is specified in both data and stringData, the value from stringData is used.
  • The keys of data and stringData must consist of alphanumeric characters, ‘-’, ‘_’ or ‘.’.
  • Newlines are not valid within these strings and must be omitted.
  • When using the base64 utility on Darwin/macOS users should avoid using the -b option to split long lines.
  • create a Secret from generators and then apply it to create the object on the Apiserver.
  • The generated Secrets name has a suffix appended by hashing the contents.
  • base64 --decode
  • Secrets can be mounted as data volumes or be exposed as environment variablesContainer environment variables are name=value pairs that provide useful information into containers running in a Pod. to be used by a container in a pod.
  • Multiple pods can reference the same secret.
  • Each key in the secret data map becomes the filename under mountPath
  • each container needs its own volumeMounts block, but only one .spec.volumes is needed per secret
  • use .spec.volumes[].secret.items field to change target path of each key:
  • If .spec.volumes[].secret.items is used, only keys specified in items are projected. To consume all keys from the secret, all of them must be listed in the items field.
  • You can also specify the permission mode bits files part of a secret will have. If you don’t specify any, 0644 is used by default.
  • JSON spec doesn’t support octal notation, so use the value 256 for 0400 permissions.
  • Inside the container that mounts a secret volume, the secret keys appear as files and the secret values are base-64 decoded and stored inside these files.
  • Mounted Secrets are updated automatically
  • Kubelet is checking whether the mounted secret is fresh on every periodic sync.
  • cache propagation delay depends on the chosen cache type
  • A container using a Secret as a subPath volume mount will not receive Secret updates.
  • Multiple pods can reference the same secret.
  • env: - name: SECRET_USERNAME valueFrom: secretKeyRef: name: mysecret key: username
  • Inside a container that consumes a secret in an environment variables, the secret keys appear as normal environment variables containing the base-64 decoded values of the secret data.
  • An imagePullSecret is a way to pass a secret that contains a Docker (or other) image registry password to the Kubelet so it can pull a private image on behalf of your Pod.
  • a secret needs to be created before any pods that depend on it.
  • Secret API objects reside in a namespaceAn abstraction used by Kubernetes to support multiple virtual clusters on the same physical cluster. . They can only be referenced by pods in that same namespace.
  • Individual secrets are limited to 1MiB in size.
  • Kubelet only supports use of secrets for Pods it gets from the API server.
  • Secrets must be created before they are consumed in pods as environment variables unless they are marked as optional.
  • References to Secrets that do not exist will prevent the pod from starting.
  • References via secretKeyRef to keys that do not exist in a named Secret will prevent the pod from starting.
  • Once a pod is scheduled, the kubelet will try to fetch the secret value.
  • Think carefully before sending your own ssh keys: other users of the cluster may have access to the secret.
  • volumes: - name: secret-volume secret: secretName: ssh-key-secret
  • Special characters such as $, \*, and ! require escaping. If the password you are using has special characters, you need to escape them using the \\ character.
  • You do not need to escape special characters in passwords from files
  • make that key begin with a dot
  • Dotfiles in secret volume
  • .secret-file
  • a frontend container which handles user interaction and business logic, but which cannot see the private key;
  • a signer container that can see the private key, and responds to simple signing requests from the frontend
  • When deploying applications that interact with the secrets API, access should be limited using authorization policies such as RBAC
  • watch and list requests for secrets within a namespace are extremely powerful capabilities and should be avoided
  • watch and list all secrets in a cluster should be reserved for only the most privileged, system-level components.
  • additional precautions with secret objects, such as avoiding writing them to disk where possible.
  • A secret is only sent to a node if a pod on that node requires it
  • only the secrets that a pod requests are potentially visible within its containers
  • each container in a pod has to request the secret volume in its volumeMounts for it to be visible within the container.
  • In the API server secret data is stored in etcdConsistent and highly-available key value store used as Kubernetes’ backing store for all cluster data.
  • limit access to etcd to admin users
  • Base64 encoding is not an encryption method and is considered the same as plain text.
  • A user who can create a pod that uses a secret can also see the value of that secret.
  • anyone with root on any node can read any secret from the apiserver, by impersonating the kubelet.
張 旭

Logstash Alternatives: Pros & Cons of 5 Log Shippers [2019] - Sematext - 0 views

sematext.com/...logstash-alternatives

log monitor system logstash fluentd

shared by 張 旭 on 05 Nov 19 - No Cached
  • In this case, Elasticsearch. And because Elasticsearch can be down or struggling, or the network can be down, the shipper would ideally be able to buffer and retry
  • Logstash is typically used for collecting, parsing, and storing logs for future use as part of log management.
  • Logstash’s biggest con or “Achille’s heel” has always been performance and resource consumption (the default heap size is 1GB).
  • ...37 more annotations...
  • This can be a problem for high traffic deployments, when Logstash servers would need to be comparable with the Elasticsearch ones.
  • Filebeat was made to be that lightweight log shipper that pushes to Logstash or Elasticsearch.
  • differences between Logstash and Filebeat are that Logstash has more functionality, while Filebeat takes less resources.
  • Filebeat is just a tiny binary with no dependencies.
  • For example, how aggressive it should be in searching for new files to tail and when to close file handles when a file didn’t get changes for a while.
  • For example, the apache module will point Filebeat to default access.log and error.log paths
  • Filebeat’s scope is very limited,
  • Initially it could only send logs to Logstash and Elasticsearch, but now it can send to Kafka and Redis, and in 5.x it also gains filtering capabilities.
  • Filebeat can parse JSON
  • you can push directly from Filebeat to Elasticsearch, and have Elasticsearch do both parsing and storing.
  • You shouldn’t need a buffer when tailing files because, just as Logstash, Filebeat remembers where it left off
  • For larger deployments, you’d typically use Kafka as a queue instead, because Filebeat can talk to Kafka as well
  • The default syslog daemon on most Linux distros, rsyslog can do so much more than just picking logs from the syslog socket and writing to /var/log/messages.
  • It can tail files, parse them, buffer (on disk and in memory) and ship to a number of destinations, including Elasticsearch.
  • rsyslog is the fastest shipper
  • Its grammar-based parsing module (mmnormalize) works at constant speed no matter the number of rules (we tested this claim).
  • use it as a simple router/shipper, any decent machine will be limited by network bandwidth
  • It’s also one of the lightest parsers you can find, depending on the configured memory buffers.
  • rsyslog requires more work to get the configuration right
  • the main difference between Logstash and rsyslog is that Logstash is easier to use while rsyslog lighter.
  • rsyslog fits well in scenarios where you either need something very light yet capable (an appliance, a small VM, collecting syslog from within a Docker container).
  • rsyslog also works well when you need that ultimate performance.
  • syslog-ng as an alternative to rsyslog (though historically it was actually the other way around).
  • a modular syslog daemon, that can do much more than just syslog
  • Unlike rsyslog, it features a clear, consistent configuration format and has nice documentation.
  • Similarly to rsyslog, you’d probably want to deploy syslog-ng on boxes where resources are tight, yet you do want to perform potentially complex processing.
  • syslog-ng has an easier, more polished feel than rsyslog, but likely not that ultimate performance
  • Fluentd was built on the idea of logging in JSON wherever possible (which is a practice we totally agree with) so that log shippers down the line don’t have to guess which substring is which field of which type.
  • Fluentd plugins are in Ruby and very easy to write.
  • structured data through Fluentd, it’s not made to have the flexibility of other shippers on this list (Filebeat excluded).
  • Fluent Bit, which is to Fluentd similar to how Filebeat is for Logstash.
  • Fluentd is a good fit when you have diverse or exotic sources and destinations for your logs, because of the number of plugins.
  • Splunk isn’t a log shipper, it’s a commercial logging solution
  • Graylog is another complete logging solution, an open-source alternative to Splunk.
  • everything goes through graylog-server, from authentication to queries.
  • Graylog is nice because you have a complete logging solution, but it’s going to be harder to customize than an ELK stack.
  • it depends
張 旭

DevOps - 0 views

mp.weixin.qq.com/...oELHwosd26dS4_qh5HEZRw

devops system

shared by 張 旭 on 27 Feb 19 - No Cached
  • 对于运维来说，知识的传承非常重要，非常有必要建立运维的知识库。一方面 有利于对事件的复盘回顾，另一方面也有助于日后参加运维的人员尽快熟悉与掌握系统的运维技能
  • 云平台主要从以下3个方面对DevOps提供支撑（括号内为承载此能力的软件工具）： 1. 基于IaaS的自服务与环境编排能力（VMWare） 2. 基于PaaS的弹性伸缩能力（K8s） 3. 基于SaaS的软件服务能力
  • 考虑自建私有云，至少是混合云。
  • ...11 more annotations...
  • 内网建立所谓的私库，作为代理与外网的公共库同步。
  • 很难做到真正意义上的DevOps to Production
  • 可视化是为了实时展现持续交付流水线执行情况与单元测试的执行报告
  • 通过持续交付流水线串联自动化测试，在测试环境部署成功后触发自动化测试。
  • 测试阶段也需要测试报告的可视化与结果通知
  • 企业的持续交付流水线往往都打不通到生产环境
  • Service Desk不是某一款软件的名字，而是ITIL（信息技术基础架构库，可认为是ITSM的落地实现）里面承载变更管理与事件管理的工具统称。
  • 构建底层的云平台，是整个DevOps基础架构的基石
  • 架构不是一成不变的，而是应该随着实际需求变化而持续演化，能力也要跟着持续提升。
  • 并行测试的执行环境通过PaaS平台按需自动生成，测试执行完毕后自动销毁。
  • 即使是雷同的项目，在对编译构建上的一些细枝末节的差别也很可能导致它们的持续交付流水线设计非常不一样。
  • 張 旭 on 27 Feb 19
     
    "对于运维来说，知识的传承非常重要，非常有必要建立运维的知识库。一方面 有利于对事件的复盘回顾，另一方面也有助于日后参加运维的人员尽快熟悉与掌握系统的运维技能。"
張 旭

bbatsov/rails-style-guide: A community-driven Ruby on Rails 4 style guide - 0 views

github.com/...rails-style-guide

rails programming code style

shared by 張 旭 on 07 May 17 - No Cached
  • custom initialization code in config/initializers. The code in initializers executes on application startup
  • Keep initialization code for each gem in a separate file with the same name as the gem
  • Mark additional assets for precompilation
  • ...90 more annotations...
  • config/environments/production.rb
  • Create an additional staging environment that closely resembles the production one
  • Keep any additional configuration in YAML files under the config/ directory
  • Rails::Application.config_for(:yaml_file)
  • Use nested routes to express better the relationship between ActiveRecord models
  • nest routes more than 1 level deep then use the shallow: true option
  • namespaced routes to group related actions
  • Don't use match to define any routes unless there is need to map multiple request types among [:get, :post, :patch, :put, :delete] to a single action using :via option.
  • Keep the controllers skinny
  • all the business logic should naturally reside in the model
  • Share no more than two instance variables between a controller and a view.
  • using a template
  • Prefer render plain: over render text
  • Prefer corresponding symbols to numeric HTTP status codes
  • without abbreviations
  • Keep your models for business logic and data-persistence only
  • Avoid altering ActiveRecord defaults (table names, primary key, etc)
  • Group macro-style methods (has_many, validates, etc) in the beginning of the class definition
  • Prefer has_many :through to has_and_belongs_to_many
  • self[:attribute]
  • self[:attribute] = value
  • validates
  • Keep custom validators under app/validators
  • Consider extracting custom validators to a shared gem
  • preferable to make a class method instead which serves the same purpose of the named scope
  • returns an ActiveRecord::Relation object
  • .update_attributes
  • Override the to_param method of the model
  • Use the friendly_id gem. It allows creation of human-readable URLs by using some descriptive attribute of the model instead of its id
  • find_each to iterate over a collection of AR objects
  • .find_each
  • .find_each
  • Looping through a collection of records from the database (using the all method, for example) is very inefficient since it will try to instantiate all the objects at once
  • always call before_destroy callbacks that perform validation with prepend: true
  • Define the dependent option to the has_many and has_one associations
  • always use the exception raising bang! method or handle the method return value.
  • When persisting AR objects
  • Avoid string interpolation in queries
  • param will be properly escaped
  • Consider using named placeholders instead of positional placeholders
  • use of find over where when you need to retrieve a single record by id
  • use of find_by over where and find_by_attribute
  • use of where.not over SQL
  • use heredocs with squish
  • Keep the schema.rb (or structure.sql) under version control.
  • Use rake db:schema:load instead of rake db:migrate to initialize an empty database
  • Enforce default values in the migrations themselves instead of in the application layer
  • change_column_default
  • imposing data integrity from the Rails app is impossible
  • use the change method instead of up and down methods.
  • constructive migrations
  • use models in migrations, make sure you define them so that you don't end up with broken migrations in the future
  • Don't use non-reversible migration commands in the change method.
  • In this case, block will be used by create_table in rollback
  • Never call the model layer directly from a view
  • Never make complex formatting in the views, export the formatting to a method in the view helper or the model.
  • When the labels of an ActiveRecord model need to be translated, use the activerecord scope
  • Separate the texts used in the views from translations of ActiveRecord attributes
  • Place the locale files for the models in a folder locales/models
  • the texts used in the views in folder locales/views
  • config/application.rb config.i18n.load_path += Dir[Rails.root.join('config', 'locales', '**', '*.{rb,yml}')]
  • I18n.t
  • I18n.l
  • Use "lazy" lookup for the texts used in views.
  • Use the dot-separated keys in the controllers and models
  • Reserve app/assets for custom stylesheets, javascripts, or images
  • Third party code such as jQuery or bootstrap should be placed in vendor/assets
  • Provide both HTML and plain-text view templates
  • config.action_mailer.raise_delivery_errors = true
  • Use a local SMTP server like Mailcatcher in the development environment
  • Provide default settings for the host name
  • The _url methods include the host name and the _path methods don't
  • _url
  • Format the from and to addresses properly
  • default from:
  • sending html emails all styles should be inline
  • Sending emails while generating page response should be avoided. It causes delays in loading of the page and request can timeout if multiple email are sent.
  • .start_with?
  • .end_with?
  • &.
  • Config your timezone accordingly in application.rb
  • config.active_record.default_timezone = :local
  • it can be only :utc or :local
  • Don't use Time.parse
  • Time.zone.parse
  • Don't use Time.now
  • Time.zone.now
  • Put gems used only for development or testing in the appropriate group in the Gemfile
  • Add all OS X specific gems to a darwin group in the Gemfile, and all Linux specific gems to a linux group
  • Do not remove the Gemfile.lock from version control.
張 旭

Securing NGINX-ingress - cert-manager Documentation - 1 views

cert-manager.io/...nginx-ingress

kubernetes ingress cert

shared by 張 旭 on 28 Jan 23 - No Cached
  • If using a ClusterIssuer, remember to update the Ingress annotation cert-manager.io/issuer to cert-manager.io/cluster-issuer
  • Certificates resources allow you to specify the details of the certificate you want to request.
  • An Issuer defines how cert-manager will request TLS certificates.
  • ...4 more annotations...
  • cert-manager mainly uses two different custom Kubernetes resources - known as CRDs - to configure and control how it operates, as well as to store state. These resources are Issuers and Certificates.
  • using annotations on the ingress with ingress-shim or directly creating a certificate resource.
  • The secret that is used in the ingress should match the secret defined in the certificate.
  • a typo will result in the ingress-nginx-controller falling back to its self-signed certificate.
  • 張 旭 on 28 Jan 23
     
    "If using a ClusterIssuer, remember to update the Ingress annotation cert-manager.io/issuer to cert-manager.io/cluster-issuer"
snow9816

Apache mpm 模組的 worker 和 prefork 差別為何 ? - 1 views

www.arthurtoday.com/...apache-mpm-worker-prefork.html

linux apache worker prefork mpm

shared by snow9816 on 02 Sep 16 - No Cached
  • 一種是採用Multi-Thread (多重執行緒 ) 的方式，另一種便是 Pre-forking (預載分流 )
  • Multi-Thread 的方式便是 worker 模組的運作方式，適合運用在多核心的 CPU 上，而 Pre-Forking 的方式則是 prefork 的運行方式，適合在多顆 CPU 執行環境
  • snow9816 on 02 Sep 16
     
    Multi-Thread 的方式便是 worker 模組的運作方式，適合運用在多核心的 CPU 上，而 Pre-Forking 的方式則是 prefork 的運行方式，適合在多顆 CPU 執行環境
張 旭

Improving Kubernetes reliability: quicker detection of a Node down | Fatal failure - 0 views

fatalfailure.wordpress.com/...icker-detection-of-a-node-down

kubernetes HA

shared by 張 旭 on 21 Jul 21 - No Cached
  • when a Node gets down, the pods of the broken node are still running for some time and they still get requests, and those requests, will fail.
  • 1- The Kubelet posts its status to the masters using –node-status-update-frequency=10s 2- A node dies 3- The kube controller manager is the one monitoring the nodes, using –-node-monitor-period=5s it checks, in the masters, the node status reported by the Kubelet. 4- Kube controller manager will see the node is unresponsive, and has this grace period –node-monitor-grace-period=40s until it considers the node unhealthy.
  • node-status-update-frequency x (N-1) != node-monitor-grace-period
  • ...2 more annotations...
  • 5- Once the node is marked as unhealthy, the kube controller manager will remove its pods based on –pod-eviction-timeout=5m0s
  • 6- Kube proxy has a watcher over the API, so the very first moment the pods are evicted the proxy will notice and update the iptables of the node, removing the endpoints from the services so the failing pods won’t be accessible anymore.
crazylion lee

GitHub - airbnb/paris: Define and apply styles to Android views programmatically - 0 views

github.com/paris

android style airbnb

shared by crazylion lee on 16 Apr 18 - No Cached
  • crazylion lee on 16 Apr 18
     
    "Define and apply styles to Android views programmatically"
張 旭

What is Data Definition Language (DDL) and how is it used? - 1 views

www.techtarget.com/...Data-Definition-Language-DDL

database sql

shared by 張 旭 on 03 Feb 23 - No Cached
  • Data Definition Language (DDL) is used to create and modify the structure of objects in a database using predefined commands and a specific syntax.
  • DDL includes Structured Query Language (SQL) statements to create and drop databases, aliases, locations, indexes, tables and sequences.
  • Since DDL includes SQL statements to define changes in the database schema, it is considered a subset of SQL.
  • ...6 more annotations...
  • Data Manipulation Language (DML), commands are used to modify data in a database. DML statements control access to the database data.
  • DDL commands are used to create, delete or alter the structure of objects in a database but not its data.
  • DDL deals with descriptions of the database schema and is useful for creating new tables, indexes, sequences, stogroups, etc. and to define the attributes of these objects, such as data type, field length and alternate table names (aliases).
  • Data Query Language (DQL) is used to get data within the schema objects of a database and also to query it and impose order upon it.
  • DQL is also a subset of SQL. One of the most common commands in DQL is SELECT.
  • The most common command types in DDL are CREATE, ALTER and DROP.
crazylion lee

JavaScript Standard Style - 0 views

standardjs.com

javascript standard

shared by crazylion lee on 15 Nov 16 - No Cached
  • crazylion lee on 15 Nov 16
     
    "One JavaScript Style Guide to Rule Them All"
張 旭

Active Record Associations - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/association_basics.html

rails database ruby relation

shared by 張 旭 on 12 Apr 16 - Cached
  • With Active Record associations, we can streamline these - and other - operations by declaratively telling Rails that there is a connection between the two models.
  • belongs_to has_one has_many has_many :through has_one :through has_and_belongs_to_many
  • an association is a connection between two Active Record models
  • ...195 more annotations...
  • Associations are implemented using macro-style calls, so that you can declaratively add features to your models
  • A belongs_to association sets up a one-to-one connection with another model, such that each instance of the declaring model "belongs to" one instance of the other model.
  • belongs_to associations must use the singular term.
  • belongs_to
  • A has_one association also sets up a one-to-one connection with another model, but with somewhat different semantics (and consequences).
  • This association indicates that each instance of a model contains or possesses one instance of another model
  • belongs_to
  • A has_many association indicates a one-to-many connection with another model.
  • This association indicates that each instance of the model has zero or more instances of another model.
  • belongs_to
  • A has_many :through association is often used to set up a many-to-many connection with another model
  • This association indicates that the declaring model can be matched with zero or more instances of another model by proceeding through a third model.
  • through:
  • through:
  • The collection of join models can be managed via the API
  • new join models are created for newly associated objects, and if some are gone their rows are deleted.
  • The has_many :through association is also useful for setting up "shortcuts" through nested has_many associations
  • A has_one :through association sets up a one-to-one connection with another model. This association indicates that the declaring model can be matched with one instance of another model by proceeding through a third model.
  • A has_and_belongs_to_many association creates a direct many-to-many connection with another model, with no intervening model.
  • id: false
  • The has_one relationship says that one of something is yours
  • using t.references :supplier instead.
  • declare a many-to-many relationship is to use has_many :through. This makes the association indirectly, through a join model
  • set up a has_many :through relationship if you need to work with the relationship model as an independent entity
  • set up a has_and_belongs_to_many relationship (though you'll need to remember to create the joining table in the database).
  • use has_many :through if you need validations, callbacks, or extra attributes on the join model
  • With polymorphic associations, a model can belong to more than one other model, on a single association.
  • belongs_to :imageable, polymorphic: true
  • a polymorphic belongs_to declaration as setting up an interface that any other model can use.
    • 張 旭
      張 旭 on 13 Apr 16
       
      _id 記錄的是不同類型的外連鍵 id；_type 記錄的是不同類型的表格名稱。
  • In designing a data model, you will sometimes find a model that should have a relation to itself
  • add a references column to the model itself
  • Controlling caching Avoiding name collisions Updating the schema Controlling association scope Bi-directional associations
  • All of the association methods are built around caching, which keeps the result of the most recent query available for further operations.
  • it is a bad idea to give an association a name that is already used for an instance method of ActiveRecord::Base. The association method would override the base method and break things.
  • You are responsible for maintaining your database schema to match your associations.
  • belongs_to associations you need to create foreign keys
  • has_and_belongs_to_many associations you need to create the appropriate join table
  • If you create an association some time after you build the underlying model, you need to remember to create an add_column migration to provide the necessary foreign key.
  • Active Record creates the name by using the lexical order of the class names
  • So a join between customer and order models will give the default join table name of "customers_orders" because "c" outranks "o" in lexical ordering.
  • For example, one would expect the tables "paper_boxes" and "papers" to generate a join table name of "papers_paper_boxes" because of the length of the name "paper_boxes", but it in fact generates a join table name of "paper_boxes_papers" (because the underscore '' is lexicographically _less than 's' in common encodings).
  • id: false
  • pass id: false to create_table because that table does not represent a model
  • By default, associations look for objects only within the current module's scope.
  • will work fine, because both the Supplier and the Account class are defined within the same scope.
  • To associate a model with a model in a different namespace, you must specify the complete class name in your association declaration:
  • class_name
  • class_name
  • Active Record provides the :inverse_of option
    • 張 旭
      張 旭 on 13 Apr 16
       
      意思是說第一次比較兩者的 first_name 是相同的；但透過 c 實體修改 first_name 之後，再次比較就不相同了，因為兩個是記憶體裡面兩個不同的物件。
  • preventing inconsistencies and making your application more efficient
  • Every association will attempt to automatically find the inverse association and set the :inverse_of option heuristically (based on the association name)
  • In database terms, this association says that this class contains the foreign key.
  • In all of these methods, association is replaced with the symbol passed as the first argument to belongs_to.
  • (force_reload = false)
  • The association method returns the associated object, if any. If no associated object is found, it returns nil.
  • the cached version will be returned.
  • The association= method assigns an associated object to this object.
  • Behind the scenes, this means extracting the primary key from the associate object and setting this object's foreign key to the same value.
  • The build_association method returns a new object of the associated type
  • but the associated object will not yet be saved.
  • The create_association method returns a new object of the associated type
  • once it passes all of the validations specified on the associated model, the associated object will be saved
  • raises ActiveRecord::RecordInvalid if the record is invalid.
  • dependent
  • counter_cache
  • :autosave :class_name :counter_cache :dependent :foreign_key :inverse_of :polymorphic :touch :validate
  • finding the number of belonging objects more efficient.
  • Although the :counter_cache option is specified on the model that includes the belongs_to declaration, the actual column must be added to the associated model.
  • add a column named orders_count to the Customer model.
  • :destroy, when the object is destroyed, destroy will be called on its associated objects.
  • deleted directly from the database without calling their destroy method.
  • Rails will not create foreign key columns for you
  • The :inverse_of option specifies the name of the has_many or has_one association that is the inverse of this association
  • set the :touch option to :true, then the updated_at or updated_on timestamp on the associated object will be set to the current time whenever this object is saved or destroyed
  • specify a particular timestamp attribute to update
  • If you set the :validate option to true, then associated objects will be validated whenever you save this object
  • By default, this is false: associated objects will not be validated when this object is saved.
  • where includes readonly select
  • make your code somewhat more efficient
  • no need to use includes for immediate associations
  • will be read-only when retrieved via the association
  • The select method lets you override the SQL SELECT clause that is used to retrieve data about the associated object
  • using the association.nil?
  • Assigning an object to a belongs_to association does not automatically save the object. It does not save the associated object either.
  • In database terms, this association says that the other class contains the foreign key.
  • the cached version will be returned.
  • :as :autosave :class_name :dependent :foreign_key :inverse_of :primary_key :source :source_type :through :validate
  • Setting the :as option indicates that this is a polymorphic association
  • :nullify causes the foreign key to be set to NULL. Callbacks are not executed.
  • It's necessary not to set or leave :nullify option for those associations that have NOT NULL database constraints.
  • The :source_type option specifies the source association type for a has_one :through association that proceeds through a polymorphic association.
  • The :source option specifies the source association name for a has_one :through association.
  • The :through option specifies a join model through which to perform the query
  • more efficient by including representatives in the association from suppliers to accounts
  • When you assign an object to a has_one association, that object is automatically saved (in order to update its foreign key).
  • If either of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
  • If the parent object (the one declaring the has_one association) is unsaved (that is, new_record? returns true) then the child objects are not saved.
  • If you want to assign an object to a has_one association without saving the object, use the association.build method
  • collection(force_reload = false) collection<<(object, ...) collection.delete(object, ...) collection.destroy(object, ...) collection=(objects) collection_singular_ids collection_singular_ids=(ids) collection.clear collection.empty? collection.size collection.find(...) collection.where(...) collection.exists?(...) collection.build(attributes = {}, ...) collection.create(attributes = {}) collection.create!(attributes = {})
  • In all of these methods, collection is replaced with the symbol passed as the first argument to has_many, and collection_singular is replaced with the singularized version of that symbol.
  • The collection<< method adds one or more objects to the collection by setting their foreign keys to the primary key of the calling model
  • The collection.delete method removes one or more objects from the collection by setting their foreign keys to NULL.
  • objects will be destroyed if they're associated with dependent: :destroy, and deleted if they're associated with dependent: :delete_all
  • The collection.destroy method removes one or more objects from the collection by running destroy on each object.
  • The collection_singular_ids method returns an array of the ids of the objects in the collection.
  • The collection_singular_ids= method makes the collection contain only the objects identified by the supplied primary key values, by adding and deleting as appropriate
  • The default strategy for has_many :through associations is delete_all, and for has_many associations is to set the foreign keys to NULL.
  • The collection.clear method removes all objects from the collection according to the strategy specified by the dependent option
  • uses the same syntax and options as ActiveRecord::Base.find
  • The collection.where method finds objects within the collection based on the conditions supplied but the objects are loaded lazily meaning that the database is queried only when the object(s) are accessed.
  • The collection.build method returns one or more new objects of the associated type. These objects will be instantiated from the passed attributes, and the link through their foreign key will be created, but the associated objects will not yet be saved.
  • The collection.create method returns a new object of the associated type. This object will be instantiated from the passed attributes, the link through its foreign key will be created, and, once it passes all of the validations specified on the associated model, the associated object will be saved.
  • :as :autosave :class_name :dependent :foreign_key :inverse_of :primary_key :source :source_type :through :validate
  • :delete_all causes all the associated objects to be deleted directly from the database (so callbacks will not execute)
  • :nullify causes the foreign keys to be set to NULL. Callbacks are not executed.
  • where includes readonly select
  • :conditions :through :polymorphic :foreign_key
  • By convention, Rails assumes that the column used to hold the primary key of the association is id. You can override this and explicitly specify the primary key with the :primary_key option.
  • The :source option specifies the source association name for a has_many :through association.
  • You only need to use this option if the name of the source association cannot be automatically inferred from the association name.
  • The :source_type option specifies the source association type for a has_many :through association that proceeds through a polymorphic association.
  • The :through option specifies a join model through which to perform the query.
  • has_many :through associations provide a way to implement many-to-many relationships,
  • By default, this is true: associated objects will be validated when this object is saved.
  • where extending group includes limit offset order readonly select uniq
  • If you use a hash-style where option, then record creation via this association will be automatically scoped using the hash
  • The extending method specifies a named module to extend the association proxy.
  • Association extensions
  • The group method supplies an attribute name to group the result set by, using a GROUP BY clause in the finder SQL.
  • has_many :line_items, -> { group 'orders.id' },                        through: :orders
  • more efficient by including line items in the association from customers to orders
  • The limit method lets you restrict the total number of objects that will be fetched through an association.
  • The offset method lets you specify the starting offset for fetching objects via an association
  • The order method dictates the order in which associated objects will be received (in the syntax used by an SQL ORDER BY clause).
  • Use the distinct method to keep the collection free of duplicates.
  • mostly useful together with the :through option
  • -> { distinct }
  • .all.inspect
  • If you want to make sure that, upon insertion, all of the records in the persisted association are distinct (so that you can be sure that when you inspect the association that you will never find duplicate records), you should add a unique index on the table itself
  • unique: true
  • Do not attempt to use include? to enforce distinctness in an association.
  • multiple users could be attempting this at the same time
  • checking for uniqueness using something like include? is subject to race conditions
  • When you assign an object to a has_many association, that object is automatically saved (in order to update its foreign key).
  • If any of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
  • If the parent object (the one declaring the has_many association) is unsaved (that is, new_record? returns true) then the child objects are not saved when they are added
  • All unsaved members of the association will automatically be saved when the parent is saved.
  • assign an object to a has_many association without saving the object, use the collection.build method
  • collection(force_reload = false) collection<<(object, ...) collection.delete(object, ...) collection.destroy(object, ...) collection=(objects) collection_singular_ids collection_singular_ids=(ids) collection.clear collection.empty? collection.size collection.find(...) collection.where(...) collection.exists?(...) collection.build(attributes = {}) collection.create(attributes = {}) collection.create!(attributes = {})
  • If the join table for a has_and_belongs_to_many association has additional columns beyond the two foreign keys, these columns will be added as attributes to records retrieved via that association.
  • Records returned with additional attributes will always be read-only
  • If you require this sort of complex behavior on the table that joins two models in a many-to-many relationship, you should use a has_many :through association instead of has_and_belongs_to_many.
  • aliased as collection.concat and collection.push.
  • The collection.delete method removes one or more objects from the collection by deleting records in the join table
  • not destroy the objects
  • The collection.destroy method removes one or more objects from the collection by running destroy on each record in the join table, including running callbacks.
  • not destroy the objects.
  • The collection.clear method removes every object from the collection by deleting the rows from the joining table.
  • not destroy the associated objects.
  • The collection.find method finds objects within the collection. It uses the same syntax and options as ActiveRecord::Base.find.
  • The collection.where method finds objects within the collection based on the conditions supplied but the objects are loaded lazily meaning that the database is queried only when the object(s) are accessed.
  • The collection.exists? method checks whether an object meeting the supplied conditions exists in the collection.
  • The collection.build method returns a new object of the associated type.
  • the associated object will not yet be saved.
  • the associated object will be saved.
  • The collection.create method returns a new object of the associated type.
  • it passes all of the validations specified on the associated model
  • :association_foreign_key :autosave :class_name :foreign_key :join_table :validate
  • The :foreign_key and :association_foreign_key options are useful when setting up a many-to-many self-join.
  • Rails assumes that the column in the join table used to hold the foreign key pointing to the other model is the name of that model with the suffix _id added.
  • If you set the :autosave option to true, Rails will save any loaded members and destroy members that are marked for destruction whenever you save the parent object.
  • By convention, Rails assumes that the column in the join table used to hold the foreign key pointing to this model is the name of this model with the suffix _id added.
  • By default, this is true: associated objects will be validated when this object is saved.
  • where extending group includes limit offset order readonly select uniq
  • set conditions via a hash
  • In this case, using @parts.assemblies.create or @parts.assemblies.build will create orders where the factory column has the value "Seattle"
  • If you use a hash-style where, then record creation via this association will be automatically scoped using the hash
  • using a GROUP BY clause in the finder SQL.
  • Use the uniq method to remove duplicates from the collection.
  • assign an object to a has_and_belongs_to_many association, that object is automatically saved (in order to update the join table).
  • If any of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
  • If the parent object (the one declaring the has_and_belongs_to_many association) is unsaved (that is, new_record? returns true) then the child objects are not saved when they are added.
  • If you want to assign an object to a has_and_belongs_to_many association without saving the object, use the collection.build method.
  • Normal callbacks hook into the life cycle of Active Record objects, allowing you to work with those objects at various points
  • define association callbacks by adding options to the association declaration
  • Rails passes the object being added or removed to the callback.
  • stack callbacks on a single event by passing them as an array
  • If a before_add callback throws an exception, the object does not get added to the collection.
  • if a before_remove callback throws an exception, the object does not get removed from the collection
  • extend these objects through anonymous modules, adding new finders, creators, or other methods.
  • order_number
  • use a named extension module
  • proxy_association.owner returns the object that the association is a part of.
張 旭

CGI、FastCGI和PHPFPM关系图解 - 歪麦博客 - 1 views

www.awaimai.com/371.html

web server CGI

shared by 張 旭 on 30 Dec 16 - No Cached
  • Web Server（如Apache）只是内容的分发者
  • Web Server 一般指Apache、Nginx、IIS、Lighttpd、Tomcat等服务器
  • Web Application 一般指PHP、Java、Asp.net等应用程序
  • ...1 more annotation...
  • Apache/Nginx + FastCGI + PHP-FPM(+PHP-CGI)
crazylion lee

SQL style guide by Simon Holywell - 0 views

www.sqlstyle.guide

guide sql

shared by crazylion lee on 12 Oct 16 - No Cached
  • crazylion lee on 12 Oct 16
     
    "SQL Style Guide"
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 19.2.1.2 Configuring an Instance for Group Repli... - 0 views

dev.mysql.com/...ion-configuring-instances.html

mysql database replication system

shared by 張 旭 on 19 Mar 17 - No Cached
  • store replication metadata in system tables instead of files
  • collect the write set and encode it as a hash using the XXHASH64 hashing algorithm
  • not start operations automatically when the server starts
  • ...10 more annotations...
  • for incoming connections from other members in the group
  • The server listens on this port for member-to-member connections. This port must not be used for user applications at all
  • The loose- prefix used for the group_replication variables above instructs the server to continue to start if the Group Replication plugin has not been loaded at the time the server is started.
  • For example, if each server instance is on a different machine use the IP and port of the machine, such as 10.0.0.1:33061. The recommended port for group_replication_local_address is 33061
  • does not need to list all members in the group
  • The server that starts the group does not make use of this option, since it is the initial server and as such, it is in charge of bootstrapping the group
  • start the bootstrap member first, and let it create the group
  • Creating a group and joining multiple members at the same time is not supported.
  • must only be used on one server instance at any time
  • Disable this option after the first server instance comes online
張 旭

Think Before you NodePort in Kubernetes - Oteemo - 0 views

oteemo.com/think-nodeport-kubernetes

kubernetes networking

shared by 張 旭 on 23 Jun 21 - No Cached
  • Two options are provided for Services intended for external use: a NodePort, or a LoadBalancer
  • no built-in cloud load balancers for Kubernetes in bare-metal environments
  • NodePort may not be your best choice.
  • ...15 more annotations...
  • NodePort, by design, bypasses almost all network security in Kubernetes.
  • NetworkPolicy resources can currently only control NodePorts by allowing or disallowing all traffic on them.
  • put a network filter in front of all the nodes
  • if a Nodeport-ranged Service is advertised to the public, it may serve as an invitation to black-hats to scan and probe
  • When Kubernetes creates a NodePort service, it allocates a port from a range specified in the flags that define your Kubernetes cluster. (By default, these are ports ranging from 30000-32767.)
  • By design, Kubernetes NodePort cannot expose standard low-numbered ports like 80 and 443, or even 8080 and 8443.
  • A port in the NodePort range can be specified manually, but this would mean the creation of a list of non-standard ports, cross-referenced with the applications they map to
  • if you want the exposed application to be highly available, everything contacting the application has to know all of your node addresses, or at least more than one.
  • non-standard ports.
  • Ingress resources use an Ingress controller (the nginx one is common but not by any means the only choice) and an external load balancer or public IP to enable path-based routing of external requests to internal Services.
  • With a single point of entry to expose and secure
  • get simpler TLS management!
  • consider putting a real load balancer in front of your NodePort Services before opening them up to the world
  • Google very recently released an alpha-stage bare-metal load balancer that, once installed in your cluster, will load-balance using BGP
  • NodePort Services are easy to create but hard to secure, hard to manage, and not especially friendly to others
張 旭

Ingress - Kubernetes - 0 views

kubernetes.io/...ingress

kubernetes networking network ingress

shared by 張 旭 on 04 Jul 19 - No Cached
  • An API object that manages external access to the services in a cluster, typically HTTP.
  • load balancing
  • SSL termination
  • ...62 more annotations...
  • name-based virtual hosting
  • Edge routerA router that enforces the firewall policy for your cluster.
  • Cluster networkA set of links, logical or physical, that facilitate communication within a cluster according to the Kubernetes networking model.
  • A Kubernetes ServiceA way to expose an application running on a set of Pods as a network service. that identifies a set of Pods using labelTags objects with identifying attributes that are meaningful and relevant to users. selectors.
  • Services are assumed to have virtual IPs only routable within the cluster network.
  • Ingress exposes HTTP and HTTPS routes from outside the cluster to services within the cluster.
  • Traffic routing is controlled by rules defined on the Ingress resource.
  • An Ingress can be configured to give Services externally-reachable URLs, load balance traffic, terminate SSL / TLS, and offer name based virtual hosting.
  • Exposing services other than HTTP and HTTPS to the internet typically uses a service of type Service.Type=NodePort or Service.Type=LoadBalancer.
  • You must have an ingress controller to satisfy an Ingress. Only creating an Ingress resource has no effect.
  • As with all other Kubernetes resources, an Ingress needs apiVersion, kind, and metadata fields
  • Ingress frequently uses annotations to configure some options depending on the Ingress controller,
  • Ingress resource only supports rules for directing HTTP traffic.
  • An optional host.
  • A list of paths
  • A backend is a combination of Service and port names
  • has an associated backend
  • Both the host and path must match the content of an incoming request before the load balancer directs traffic to the referenced Service.
  • HTTP (and HTTPS) requests to the Ingress that matches the host and path of the rule are sent to the listed backend.
  • A default backend is often configured in an Ingress controller to service any requests that do not match a path in the spec.
  • An Ingress with no rules sends all traffic to a single default backend.
  • Ingress controllers and load balancers may take a minute or two to allocate an IP address.
  • A fanout configuration routes traffic from a single IP address to more than one Service, based on the HTTP URI being requested.
  • nginx.ingress.kubernetes.io/rewrite-target: /
  • describe ingress
  • get ingress
  • Name-based virtual hosts support routing HTTP traffic to multiple host names at the same IP address.
  • route requests based on the Host header.
  • an Ingress resource without any hosts defined in the rules, then any web traffic to the IP address of your Ingress controller can be matched without a name based virtual host being required.
  • secure an Ingress by specifying a SecretStores sensitive information, such as passwords, OAuth tokens, and ssh keys. that contains a TLS private key and certificate.
  • Currently the Ingress only supports a single TLS port, 443, and assumes TLS termination.
  • An Ingress controller is bootstrapped with some load balancing policy settings that it applies to all Ingress, such as the load balancing algorithm, backend weight scheme, and others.
  • persistent sessions, dynamic weights) are not yet exposed through the Ingress. You can instead get these features through the load balancer used for a Service.
  • review the controller specific documentation to see how they handle health checks
  • edit ingress
  • After you save your changes, kubectl updates the resource in the API server, which tells the Ingress controller to reconfigure the load balancer.
  • kubectl replace -f on a modified Ingress YAML file.
  • Node: A worker machine in Kubernetes, part of a cluster.
  • in most common Kubernetes deployments, nodes in the cluster are not part of the public internet.
  • Edge router: A router that enforces the firewall policy for your cluster.
  • a gateway managed by a cloud provider or a physical piece of hardware.
  • Cluster network: A set of links, logical or physical, that facilitate communication within a cluster according to the Kubernetes networking model.
  • Service: A Kubernetes Service that identifies a set of Pods using label selectors.
  • An Ingress may be configured to give Services externally-reachable URLs, load balance traffic, terminate SSL / TLS, and offer name-based virtual hosting.
  • An Ingress does not expose arbitrary ports or protocols.
  • You must have an Ingress controller to satisfy an Ingress. Only creating an Ingress resource has no effect.
  • The name of an Ingress object must be a valid DNS subdomain name
  • The Ingress spec has all the information needed to configure a load balancer or proxy server.
  • Ingress resource only supports rules for directing HTTP(S) traffic.
  • An Ingress with no rules sends all traffic to a single default backend and .spec.defaultBackend is the backend that should handle requests in that case.
  • If defaultBackend is not set, the handling of requests that do not match any of the rules will be up to the ingress controller
  • A common usage for a Resource backend is to ingress data to an object storage backend with static assets.
  • Exact: Matches the URL path exactly and with case sensitivity.
  • Prefix: Matches based on a URL path prefix split by /. Matching is case sensitive and done on a path element by element basis.
  • multiple paths within an Ingress will match a request. In those cases precedence will be given first to the longest matching path.
  • Hosts can be precise matches (for example “foo.bar.com”) or a wildcard (for example “*.foo.com”).
  • No match, wildcard only covers a single DNS label
  • Each Ingress should specify a class, a reference to an IngressClass resource that contains additional configuration including the name of the controller that should implement the class.
  • secure an Ingress by specifying a Secret that contains a TLS private key and certificate.
  • The Ingress resource only supports a single TLS port, 443, and assumes TLS termination at the ingress point (traffic to the Service and its Pods is in plaintext).
  • TLS will not work on the default rule because the certificates would have to be issued for all the possible sub-domains.
  • hosts in the tls section need to explicitly match the host in the rules section.
張 旭

Syntax - Configuration Language | Terraform | HashiCorp Developer - 0 views

developer.hashicorp.com/...configuration

devops terraform

shared by 張 旭 on 22 Jan 23 - No Cached
  • the native syntax of the Terraform language, which is a rich language designed to be relatively easy for humans to read and write.
  • Terraform's configuration language is based on a more general language called HCL, and HCL's documentation usually uses the word "attribute" instead of "argument."
  • A particular block type may have any number of required labels, or it may require none
  • ...34 more annotations...
  • After the block type keyword and any labels, the block body is delimited by the { and } characters
  • Identifiers can contain letters, digits, underscores (_), and hyphens (-). The first character of an identifier must not be a digit, to avoid ambiguity with literal numbers.
  • The # single-line comment style is the default comment style and should be used in most cases.
  • he idiomatic style is to use the Unix convention
  • Indent two spaces for each nesting level.
  • align their equals signs
  • Use empty lines to separate logical groups of arguments within a block.
  • Use one blank line to separate the arguments from the blocks.
  • "meta-arguments" (as defined by the Terraform language semantics)
  • Avoid separating multiple blocks of the same type with other blocks of a different type, unless the block types are defined by semantics to form a family.
  • Resource names must start with a letter or underscore, and may contain only letters, digits, underscores, and dashes.
  • Each resource is associated with a single resource type, which determines the kind of infrastructure object it manages and what arguments and other attributes the resource supports.
  • Each resource type is implemented by a provider, which is a plugin for Terraform that offers a collection of resource types.
  • By convention, resource type names start with their provider's preferred local name.
  • Most publicly available providers are distributed on the Terraform Registry, which also hosts their documentation.
  • The Terraform language defines several meta-arguments, which can be used with any resource type to change the behavior of resources.
  • use precondition and postcondition blocks to specify assumptions and guarantees about how the resource operates.
  • Some resource types provide a special timeouts nested block argument that allows you to customize how long certain operations are allowed to take before being considered to have failed.
  • Timeouts are handled entirely by the resource type implementation in the provider
  • Most resource types do not support the timeouts block at all.
  • A resource block declares that you want a particular infrastructure object to exist with the given settings.
  • Destroy resources that exist in the state but no longer exist in the configuration.
  • Destroy and re-create resources whose arguments have changed but which cannot be updated in-place due to remote API limitations.
  • Expressions within a Terraform module can access information about resources in the same module, and you can use that information to help configure other resources. Use the <RESOURCE TYPE>.<NAME>.<ATTRIBUTE> syntax to reference a resource attribute in an expression.
  • resources often provide read-only attributes with information obtained from the remote API; this often includes things that can't be known until the resource is created, like the resource's unique random ID.
  • data sources, which are a special type of resource used only for looking up information.
  • some dependencies cannot be recognized implicitly in configuration.
  • local-only resource types exist for generating private keys, issuing self-signed TLS certificates, and even generating random ids.
  • The behavior of local-only resources is the same as all other resources, but their result data exists only within the Terraform state.
  • The count meta-argument accepts a whole number, and creates that many instances of the resource or module.
  • count.index — The distinct index number (starting with 0) corresponding to this instance.
  • the count value must be known before Terraform performs any remote resource actions. This means count can't refer to any resource attributes that aren't known until after a configuration is applied
  • Within nested provisioner or connection blocks, the special self object refers to the current resource instance, not the resource block as a whole.
  • This was fragile, because the resource instances were still identified by their index instead of the string values in the list.
  • 張 旭 on 22 Jan 23
     
    "the native syntax of the Terraform language, which is a rich language designed to be relatively easy for humans to read and write. "
張 旭

Cluster Networking - Kubernetes - 0 views

kubernetes.io/...networking

kubernetes networking network system

shared by 張 旭 on 08 Jul 19 - No Cached
  • Networking is a central part of Kubernetes, but it can be challenging to understand exactly how it is expected to work
  • Highly-coupled container-to-container communications
  • Pod-to-Pod communications
  • ...57 more annotations...
  • this is the primary focus of this document
    • 張 旭
      張 旭 on 27 Aug 21
       
      Cluster Networking 所關注處理的是： Pod 到 Pod 之間的連線
  • Pod-to-Service communications
  • External-to-Service communications
  • Kubernetes is all about sharing machines between applications.
  • sharing machines requires ensuring that two applications do not try to use the same ports.
  • Dynamic port allocation brings a lot of complications to the system
  • Every Pod gets its own IP address
  • do not need to explicitly create links between Pods
  • almost never need to deal with mapping container ports to host ports.
  • Pods can be treated much like VMs or physical hosts from the perspectives of port allocation, naming, service discovery, load balancing, application configuration, and migration.
  • pods on a node can communicate with all pods on all nodes without NAT
  • agents on a node (e.g. system daemons, kubelet) can communicate with all pods on that node
  • pods in the host network of a node can communicate with all pods on all nodes without NAT
  • If your job previously ran in a VM, your VM had an IP and could talk to other VMs in your project. This is the same basic model.
  • containers within a Pod share their network namespaces - including their IP address
  • containers within a Pod can all reach each other’s ports on localhost
  • containers within a Pod must coordinate port usage
  • “IP-per-pod” model.
  • request ports on the Node itself which forward to your Pod (called host ports), but this is a very niche operation
  • The Pod itself is blind to the existence or non-existence of host ports.
  • AOS is an Intent-Based Networking system that creates and manages complex datacenter environments from a simple integrated platform.
  • Cisco Application Centric Infrastructure offers an integrated overlay and underlay SDN solution that supports containers, virtual machines, and bare metal servers.
  • AOS Reference Design currently supports Layer-3 connected hosts that eliminate legacy Layer-2 switching problems.
  • The AWS VPC CNI offers integrated AWS Virtual Private Cloud (VPC) networking for Kubernetes clusters.
  • users can apply existing AWS VPC networking and security best practices for building Kubernetes clusters.
  • Using this CNI plugin allows Kubernetes pods to have the same IP address inside the pod as they do on the VPC network.
  • The CNI allocates AWS Elastic Networking Interfaces (ENIs) to each Kubernetes node and using the secondary IP range from each ENI for pods on the node.
  • Big Cloud Fabric is a cloud native networking architecture, designed to run Kubernetes in private cloud/on-premises environments.
  • Cilium is L7/HTTP aware and can enforce network policies on L3-L7 using an identity based security model that is decoupled from network addressing.
  • CNI-Genie is a CNI plugin that enables Kubernetes to simultaneously have access to different implementations of the Kubernetes network model in runtime.
  • CNI-Genie also supports assigning multiple IP addresses to a pod, each from a different CNI plugin.
  • cni-ipvlan-vpc-k8s contains a set of CNI and IPAM plugins to provide a simple, host-local, low latency, high throughput, and compliant networking stack for Kubernetes within Amazon Virtual Private Cloud (VPC) environments by making use of Amazon Elastic Network Interfaces (ENI) and binding AWS-managed IPs into Pods using the Linux kernel’s IPvlan driver in L2 mode.
  • to be straightforward to configure and deploy within a VPC
  • Contiv provides configurable networking
  • Contrail, based on Tungsten Fabric, is a truly open, multi-cloud network virtualization and policy management platform.
  • DANM is a networking solution for telco workloads running in a Kubernetes cluster.
  • Flannel is a very simple overlay network that satisfies the Kubernetes requirements.
  • Any traffic bound for that subnet will be routed directly to the VM by the GCE network fabric.
  • sysctl net.ipv4.ip_forward=1
  • Jaguar provides overlay network using vxlan and Jaguar CNIPlugin provides one IP address per pod.
  • Knitter is a network solution which supports multiple networking in Kubernetes.
  • Kube-OVN is an OVN-based kubernetes network fabric for enterprises.
  • Kube-router provides a Linux LVS/IPVS-based service proxy, a Linux kernel forwarding-based pod-to-pod networking solution with no overlays, and iptables/ipset-based network policy enforcer.
  • If you have a “dumb” L2 network, such as a simple switch in a “bare-metal” environment, you should be able to do something similar to the above GCE setup.
  • Multus is a Multi CNI plugin to support the Multi Networking feature in Kubernetes using CRD based network objects in Kubernetes.
  • NSX-T can provide network virtualization for a multi-cloud and multi-hypervisor environment and is focused on emerging application frameworks and architectures that have heterogeneous endpoints and technology stacks.
  • NSX-T Container Plug-in (NCP) provides integration between NSX-T and container orchestrators such as Kubernetes
  • Nuage uses the open source Open vSwitch for the data plane along with a feature rich SDN Controller built on open standards.
  • OpenVSwitch is a somewhat more mature but also complicated way to build an overlay network
  • OVN is an opensource network virtualization solution developed by the Open vSwitch community.
  • Project Calico is an open source container networking provider and network policy engine.
  • Calico provides a highly scalable networking and network policy solution for connecting Kubernetes pods based on the same IP networking principles as the internet
  • Calico can be deployed without encapsulation or overlays to provide high-performance, high-scale data center networking.
  • Calico can also be run in policy enforcement mode in conjunction with other networking solutions such as Flannel, aka canal, or native GCE, AWS or Azure networking.
  • Romana is an open source network and security automation solution that lets you deploy Kubernetes without an overlay network
  • Weave Net runs as a CNI plug-in or stand-alone. In either version, it doesn’t require any configuration or extra code to run, and in both cases, the network provides one IP address per pod - as is standard for Kubernetes.
  • The network model is implemented by the container runtime on each node.
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