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張 旭

Choosing an Executor Type - CircleCI - 0 views

circleci.com/...executor-types

circle CI

shared by 張 旭 on 14 Nov 18 - No Cached
  • Containers are an instance of the Docker Image you specify and the first image listed in your configuration is the primary container image in which all steps run.
  • In this example, all steps run in the container created by the first image listed under the build job
  • If you experience increases in your run times due to installing additional tools during execution, it is best practice to use the Building Custom Docker Images Documentation to create a custom image with tools that are pre-loaded in the container to meet the job requirements.
  • ...9 more annotations...
  • The machine option runs your jobs in a dedicated, ephemeral VM
  • Using the machine executor gives your application full access to OS resources and provides you with full control over the job environment.
  • Using machine may require additional fees in a future pricing update.
  • Using the macos executor allows you to run your job in a macOS environment on a VM.
  • In a multi-image configuration job, all steps are executed in the container created by the first image listed.
  • All containers run in a common network and every exposed port will be available on localhost from a primary container.
  • If you want to work with private images/registries, please refer to Using Private Images.
  • Docker also has built-in image caching and enables you to build, run, and publish Docker images via Remote Docker.
  • if you require low-level access to the network or need to mount external volumes consider using machine
張 旭

How To Benchmark HTTP Latency with wrk on Ubuntu 14.04 | DigitalOcean - 0 views

www.digitalocean.com/...tency-with-wrk-on-ubuntu-14-04

performance website server test

shared by 張 旭 on 31 Jan 19 - No Cached
  • wrk, which measures the latency of your HTTP services at high loads.
  • Latency refers to the time interval between the moment the request was made (by wrk) and the moment the response was received (from the service).
  • Tests can't be compared to real users, but they should give you a good estimate of expected latency
張 旭

DNS Records: an Introduction - 0 views

linode.com/...dns-records-an-introduction

dns server networking

shared by 張 旭 on 26 Mar 18 - No Cached
  • reading from right to left
  • top-level domain, or TLD
  • first-level subdomains plus their TLDs (example.com) are referred to as “domains.”
  • ...37 more annotations...
  • Name servers host a domain’s DNS information in a text file called the zone file
  • Start of Authority (SOA) records
  • You’ll want to specify at least two name servers. That way, if one of them is down, the next one can continue to serve your DNS information.
  • Every domain’s zone file contains the admin’s email address, the name servers, and the DNS records.
  • a zone file, which lists domains and their corresponding IP addresses (and a few other things)
  • TLD nameserver
  • ISPs cache a lot of DNS information after they’ve looked it up the first time
  • Usually caching is a good thing, but it can be a problem if you’ve recently made a change to your DNS information
  • An A record matches up a domain (or subdomain) to an IP address
  • point different subdomains to different IP addresses
  • An AAAA record is just like an A record, but for IPv6 IP addresses.
  • An AXFR record is a type of DNS record used for DNS replication
  • used on a slave DNS server to replicate the zone file from a master DNS server
  • DNS Certification Authority Authorization uses DNS to allow the holder of a domain to specify which certificate authorities are allowed to issue certificates for that domain.
  • A CNAME record or Canonical Name record matches up a domain (or subdomain) to a different domain.
  • You should not use a CNAME record for a domain that gets email, because some mail servers handle mail oddly for domains with CNAME records
  • the target domain for a CNAME record should have a normal A-record resolution
  • a CNAME record does not function the same way as a URL redirect
  • A DKIM record or domain keys identified mail record displays the public key for authenticating messages that have been signed with the DKIM protocol
  • An MX record or mail exchange record sets the mail delivery destination for a domain (or subdomain).
  • Ideally, an MX record should point to a domain that is also the hostname for its server.
  • Your MX records don’t necessarily have to point to your Linode. If you’re using a third-party mail service, like Google Apps, you should use the MX records they provide.
  • Lower numbers have a higher priority
  • NS records or name server records set the nameservers for a domain (or subdomain).
  • You can also set up different nameservers for any of your subdomains.
  • The order of NS records does not matter; DNS requests are sent randomly to the different servers, and if one host fails to respond, another one will be queried.
  • A PTR record or pointer record matches up an IP address to a domain (or subdomain), allowing reverse DNS queries to function.
  • PTR records are usually set with your hosting provider. They are not part of your domain’s zone file.
  • An SOA record or Start of Authority record labels a zone file with the name of the host where it was originally created.
  • The administrative email address is written with a period (.) instead of an at symbol (<@>).
  • The single nameserver mentioned in the SOA record is considered the primary master for the purposes of Dynamic DNS and is the server where zone file changes get made before they are propagated to all other nameservers.
  • An SPF record or Sender Policy Framework record lists the designated mail servers for a domain (or subdomain).
  • An SPF record for your domain tells other receiving mail servers which outgoing server(s) are valid sources of email, so they can reject spoofed email from your domain that has originated from unauthorized servers.
  • Your SPF record will have a domain or subdomain, type (which is TXT, or SPF if your name server supports it), and text (which starts with “v=spf1” and contains the SPF record settings).
  • An SRV record or service record matches up a specific service that runs on your domain (or subdomain) to a target domain.
  • A TXT record or text record provides information about the domain in question to other resources on the Internet.
  • One common use of the TXT record is to create an SPF record on nameservers that don’t natively support SPF.
張 旭

Glossary - CircleCI - 0 views

circleci.com/glossary

circleci CI system deploy

shared by 張 旭 on 25 Nov 18 - No Cached
  • User authentication may use LDAP for an instance of the CircleCI application that is installed on your private server or cloud
  • The first user to log into a private installation of CircleCI
  • Contexts provide a mechanism for securing and sharing environment variables across projects.
  • ...22 more annotations...
  • The environment variables are defined as name/value pairs and are injected at runtime.
  • The CircleCI Docker Layer Caching feature allows builds to reuse Docker image layers
  • from previous builds.
  • Image layers are stored in separate volumes in the cloud and are not shared between projects.
  • Layers may only be used by builds from the same project.
  • Environment variables store customer data that is used by a project.
  • Defines the underlying technology to run a job.
  • machine to run your job inside a full virtual machine.
  • docker to run your job inside a Docker container with a specified image
  • A job is a collection of steps.
  • The first image listed in config.yml
  • A CircleCI project shares the name of the code repository for which it automates workflows, tests, and deployment.
  • must be added with the Add Project button
  • Following a project enables a user to subscribe to email notifications for the project build status and adds the project to their CircleCI dashboard.
  • A step is a collection of executable commands
  • Users must be added to a GitHub or Bitbucket org to view or follow associated CircleCI projects.
  • Users may not view project data that is stored in environment variables.  
  • A Workflow is a set of rules for defining a collection of jobs and their run order.
  • Workflows are implemented as a directed acyclic graph (DAG) of jobs for greatest flexibility.
  • referred to as Pipelines
  • A workspace is a workflows-aware storage mechanism.
  • A workspace stores data unique to the job, which may be needed in downstream jobs.
張 旭

Helm | - 0 views

helm.sh/developing_charts

helm kubernetes chart development devops package

shared by 張 旭 on 05 Aug 19 - No Cached
  • A chart is a collection of files that describe a related set of Kubernetes resources.
  • A single chart might be used to deploy something simple, like a memcached pod, or something complex, like a full web app stack with HTTP servers, databases, caches, and so on.
  • Charts are created as files laid out in a particular directory tree, then they can be packaged into versioned archives to be deployed.
  • ...170 more annotations...
  • A chart is organized as a collection of files inside of a directory.
  • values.yaml # The default configuration values for this chart
  • charts/ # A directory containing any charts upon which this chart depends.
  • templates/ # A directory of templates that, when combined with values, # will generate valid Kubernetes manifest files.
  • version: A SemVer 2 version (required)
  • apiVersion: The chart API version, always "v1" (required)
  • Every chart must have a version number. A version must follow the SemVer 2 standard.
  • non-SemVer names are explicitly disallowed by the system.
  • When generating a package, the helm package command will use the version that it finds in the Chart.yaml as a token in the package name.
  • the appVersion field is not related to the version field. It is a way of specifying the version of the application.
  • appVersion: The version of the app that this contains (optional). This needn't be SemVer.
  • If the latest version of a chart in the repository is marked as deprecated, then the chart as a whole is considered to be deprecated.
  • deprecated: Whether this chart is deprecated (optional, boolean)
  • one chart may depend on any number of other charts.
  • dependencies can be dynamically linked through the requirements.yaml file or brought in to the charts/ directory and managed manually.
  • the preferred method of declaring dependencies is by using a requirements.yaml file inside of your chart.
  • A requirements.yaml file is a simple file for listing your dependencies.
  • The repository field is the full URL to the chart repository.
  • you must also use helm repo add to add that repo locally.
  • helm dependency update and it will use your dependency file to download all the specified charts into your charts/ directory for you.
  • When helm dependency update retrieves charts, it will store them as chart archives in the charts/ directory.
  • Managing charts with requirements.yaml is a good way to easily keep charts updated, and also share requirements information throughout a team.
  • All charts are loaded by default.
  • The condition field holds one or more YAML paths (delimited by commas). If this path exists in the top parent’s values and resolves to a boolean value, the chart will be enabled or disabled based on that boolean value.
  • The tags field is a YAML list of labels to associate with this chart.
  • all charts with tags can be enabled or disabled by specifying the tag and a boolean value.
  • The --set parameter can be used as usual to alter tag and condition values.
  • Conditions (when set in values) always override tags.
  • The first condition path that exists wins and subsequent ones for that chart are ignored.
  • The keys containing the values to be imported can be specified in the parent chart’s requirements.yaml file using a YAML list. Each item in the list is a key which is imported from the child chart’s exports field.
  • specifying the key data in our import list, Helm looks in the exports field of the child chart for data key and imports its contents.
  • the parent key data is not contained in the parent’s final values. If you need to specify the parent key, use the ‘child-parent’ format.
  • To access values that are not contained in the exports key of the child chart’s values, you will need to specify the source key of the values to be imported (child) and the destination path in the parent chart’s values (parent).
  • To drop a dependency into your charts/ directory, use the helm fetch command
  • A dependency can be either a chart archive (foo-1.2.3.tgz) or an unpacked chart directory.
  • name cannot start with _ or .. Such files are ignored by the chart loader.
  • a single release is created with all the objects for the chart and its dependencies.
  • Helm Chart templates are written in the Go template language, with the addition of 50 or so add-on template functions from the Sprig library and a few other specialized functions
  • When Helm renders the charts, it will pass every file in that directory through the template engine.
  • Chart developers may supply a file called values.yaml inside of a chart. This file can contain default values.
  • Chart users may supply a YAML file that contains values. This can be provided on the command line with helm install.
  • When a user supplies custom values, these values will override the values in the chart’s values.yaml file.
  • Template files follow the standard conventions for writing Go templates
  • {{default "minio" .Values.storage}}
  • Values that are supplied via a values.yaml file (or via the --set flag) are accessible from the .Values object in a template.
  • pre-defined, are available to every template, and cannot be overridden
  • the names are case sensitive
  • Release.Name: The name of the release (not the chart)
  • Release.IsUpgrade: This is set to true if the current operation is an upgrade or rollback.
  • Release.Revision: The revision number. It begins at 1, and increments with each helm upgrade
  • Chart: The contents of the Chart.yaml
  • Files: A map-like object containing all non-special files in the chart.
  • Files can be accessed using {{index .Files "file.name"}} or using the {{.Files.Get name}} or {{.Files.GetString name}} functions.
  • .helmignore
  • access the contents of the file as []byte using {{.Files.GetBytes}}
  • Any unknown Chart.yaml fields will be dropped
  • Chart.yaml cannot be used to pass arbitrarily structured data into the template.
  • A values file is formatted in YAML.
  • A chart may include a default values.yaml file
  • be merged into the default values file.
  • The default values file included inside of a chart must be named values.yaml
  • accessible inside of templates using the .Values object
  • Values files can declare values for the top-level chart, as well as for any of the charts that are included in that chart’s charts/ directory.
  • Charts at a higher level have access to all of the variables defined beneath.
  • lower level charts cannot access things in parent charts
  • Values are namespaced, but namespaces are pruned.
  • the scope of the values has been reduced and the namespace prefix removed
  • Helm supports special “global” value.
  • a way of sharing one top-level variable with all subcharts, which is useful for things like setting metadata properties like labels.
  • If a subchart declares a global variable, that global will be passed downward (to the subchart’s subcharts), but not upward to the parent chart.
  • global variables of parent charts take precedence over the global variables from subcharts.
  • helm lint
  • A chart repository is an HTTP server that houses one or more packaged charts
  • Any HTTP server that can serve YAML files and tar files and can answer GET requests can be used as a repository server.
  • Helm does not provide tools for uploading charts to remote repository servers.
  • the only way to add a chart to $HELM_HOME/starters is to manually copy it there.
  • Helm provides a hook mechanism to allow chart developers to intervene at certain points in a release’s life cycle.
  • Execute a Job to back up a database before installing a new chart, and then execute a second job after the upgrade in order to restore data.
  • Hooks are declared as an annotation in the metadata section of a manifest
  • Hooks work like regular templates, but they have special annotations
  • pre-install
  • post-install: Executes after all resources are loaded into Kubernetes
  • pre-delete
  • post-delete: Executes on a deletion request after all of the release’s resources have been deleted.
  • pre-upgrade
  • post-upgrade
  • pre-rollback
  • post-rollback: Executes on a rollback request after all resources have been modified.
  • crd-install
  • test-success: Executes when running helm test and expects the pod to return successfully (return code == 0).
  • test-failure: Executes when running helm test and expects the pod to fail (return code != 0).
  • Hooks allow you, the chart developer, an opportunity to perform operations at strategic points in a release lifecycle
  • Tiller then loads the hook with the lowest weight first (negative to positive)
  • Tiller returns the release name (and other data) to the client
  • If the resources is a Job kind, Tiller will wait until the job successfully runs to completion.
  • if the job fails, the release will fail. This is a blocking operation, so the Helm client will pause while the Job is run.
  • If they have hook weights (see below), they are executed in weighted order. Otherwise, ordering is not guaranteed.
  • good practice to add a hook weight, and set it to 0 if weight is not important.
  • The resources that a hook creates are not tracked or managed as part of the release.
  • leave the hook resource alone.
  • To destroy such resources, you need to either write code to perform this operation in a pre-delete or post-delete hook or add "helm.sh/hook-delete-policy" annotation to the hook template file.
  • Hooks are just Kubernetes manifest files with special annotations in the metadata section
  • One resource can implement multiple hooks
  • no limit to the number of different resources that may implement a given hook.
  • When subcharts declare hooks, those are also evaluated. There is no way for a top-level chart to disable the hooks declared by subcharts.
  • Hook weights can be positive or negative numbers but must be represented as strings.
  • sort those hooks in ascending order.
  • Hook deletion policies
  • "before-hook-creation" specifies Tiller should delete the previous hook before the new hook is launched.
  • By default Tiller will wait for 60 seconds for a deleted hook to no longer exist in the API server before timing out.
  • Custom Resource Definitions (CRDs) are a special kind in Kubernetes.
  • The crd-install hook is executed very early during an installation, before the rest of the manifests are verified.
  • A common reason why the hook resource might already exist is that it was not deleted following use on a previous install/upgrade.
  • Helm uses Go templates for templating your resource files.
  • two special template functions: include and required
  • include function allows you to bring in another template, and then pass the results to other template functions.
  • The required function allows you to declare a particular values entry as required for template rendering.
  • If the value is empty, the template rendering will fail with a user submitted error message.
  • When you are working with string data, you are always safer quoting the strings than leaving them as bare words
  • Quote Strings, Don’t Quote Integers
  • when working with integers do not quote the values
  • env variables values which are expected to be string
  • to include a template, and then perform an operation on that template’s output, Helm has a special include function
  • The above includes a template called toYaml, passes it $value, and then passes the output of that template to the nindent function.
  • Go provides a way for setting template options to control behavior when a map is indexed with a key that’s not present in the map
  • The required function gives developers the ability to declare a value entry as required for template rendering.
  • The tpl function allows developers to evaluate strings as templates inside a template.
  • Rendering a external configuration file
  • (.Files.Get "conf/app.conf")
  • Image pull secrets are essentially a combination of registry, username, and password.
  • Automatically Roll Deployments When ConfigMaps or Secrets change
  • configmaps or secrets are injected as configuration files in containers
  • a restart may be required should those be updated with a subsequent helm upgrade
  • The sha256sum function can be used to ensure a deployment’s annotation section is updated if another file changes
  • checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
  • helm upgrade --recreate-pods
  • "helm.sh/resource-policy": keep
  • resources that should not be deleted when Helm runs a helm delete
  • this resource becomes orphaned. Helm will no longer manage it in any way.
  • create some reusable parts in your chart
  • In the templates/ directory, any file that begins with an underscore(_) is not expected to output a Kubernetes manifest file.
  • by convention, helper templates and partials are placed in a _helpers.tpl file.
  • The current best practice for composing a complex application from discrete parts is to create a top-level umbrella chart that exposes the global configurations, and then use the charts/ subdirectory to embed each of the components.
  • SAP’s Converged charts: These charts install SAP Converged Cloud a full OpenStack IaaS on Kubernetes. All of the charts are collected together in one GitHub repository, except for a few submodules.
  • Deis’s Workflow: This chart exposes the entire Deis PaaS system with one chart. But it’s different from the SAP chart in that this umbrella chart is built from each component, and each component is tracked in a different Git repository.
  • YAML is a superset of JSON
  • any valid JSON structure ought to be valid in YAML.
  • As a best practice, templates should follow a YAML-like syntax unless the JSON syntax substantially reduces the risk of a formatting issue.
  • There are functions in Helm that allow you to generate random data, cryptographic keys, and so on.
  • a chart repository is a location where packaged charts can be stored and shared.
  • A chart repository is an HTTP server that houses an index.yaml file and optionally some packaged charts.
  • Because a chart repository can be any HTTP server that can serve YAML and tar files and can answer GET requests, you have a plethora of options when it comes down to hosting your own chart repository.
  • It is not required that a chart package be located on the same server as the index.yaml file.
  • A valid chart repository must have an index file. The index file contains information about each chart in the chart repository.
  • The Helm project provides an open-source Helm repository server called ChartMuseum that you can host yourself.
  • $ helm repo index fantastic-charts --url https://fantastic-charts.storage.googleapis.com
  • A repository will not be added if it does not contain a valid index.yaml
  • add the repository to their helm client via the helm repo add [NAME] [URL] command with any name they would like to use to reference the repository.
  • Helm has provenance tools which help chart users verify the integrity and origin of a package.
  • Integrity is established by comparing a chart to a provenance record
  • The provenance file contains a chart’s YAML file plus several pieces of verification information
  • Chart repositories serve as a centralized collection of Helm charts.
  • Chart repositories must make it possible to serve provenance files over HTTP via a specific request, and must make them available at the same URI path as the chart.
  • We don’t want to be “the certificate authority” for all chart signers. Instead, we strongly favor a decentralized model, which is part of the reason we chose OpenPGP as our foundational technology.
  • The Keybase platform provides a public centralized repository for trust information.
  • A chart contains a number of Kubernetes resources and components that work together.
  • A test in a helm chart lives under the templates/ directory and is a pod definition that specifies a container with a given command to run.
  • The pod definition must contain one of the helm test hook annotations: helm.sh/hook: test-success or helm.sh/hook: test-failure
  • helm test
  • nest your test suite under a tests/ directory like <chart-name>/templates/tests/
張 旭

DNS Records: An Introduction - 0 views

www.linode.com/...dns-records-an-introduction

dns networking system

shared by 張 旭 on 28 Aug 19 - No Cached
  • Domain names are best understood by reading from right to left.
  • the top-level domain, or TLD
  • Every term to the left of the TLD is separated by a period and considered a more specific subdomain
  • ...40 more annotations...
  • Name servers host a domain’s DNS information in a text file called a zone file.
  • Start of Authority (SOA) records
  • specifying DNS records, which match domain names to IP addresses.
  • Every domain’s zone file contains the domain administrator’s email address, the name servers, and the DNS records.
  • Your ISP’s DNS resolver queries a root nameserver for the proper TLD nameserver. In other words, it asks the root nameserver, *Where can I find the nameserver for .com domains?*
  • In actuality, ISPs cache a lot of DNS information after they’ve looked it up the first time.
  • caching is a good thing, but it can be a problem if you’ve recently made a change to your DNS information
  • An A record points your domain or subdomain to your Linode’s IP address,
  • use an asterisk (*) as your subdomain
  • An AAAA record is just like an A record, but for IPv6 IP addresses.
  • An AXFR record is a type of DNS record used for DNS replication
  • DNS Certification Authority Authorization uses DNS to allow the holder of a domain to specify which certificate authorities are allowed to issue certificates for that domain.
  • A CNAME record or Canonical Name record matches a domain or subdomain to a different domain.
  • Some mail servers handle mail oddly for domains with CNAME records, so you should not use a CNAME record for a domain that gets email.
  • MX records cannot reference CNAME-defined hostnames.
  • Chaining or looping CNAME records is not recommended.
  • a CNAME record does not function the same way as a URL redirect.
  • A DKIM record or DomainKeys Identified Mail record displays the public key for authenticating messages that have been signed with the DKIM protocol
  • DKIM records are implemented as text records.
  • An MX record or mail exchanger record sets the mail delivery destination for a domain or subdomain.
  • An MX record should ideally point to a domain that is also the hostname for its server.
  • Priority allows you to designate a fallback server (or servers) for mail for a particular domain. Lower numbers have a higher priority.
  • NS records or name server records set the nameservers for a domain or subdomain.
  • You can also set up different nameservers for any of your subdomains
  • Primary nameservers get configured at your registrar and secondary subdomain nameservers get configured in the primary domain’s zone file.
  • The order of NS records does not matter. DNS requests are sent randomly to the different servers
  • A PTR record or pointer record matches up an IP address to a domain or subdomain, allowing reverse DNS queries to function.
  • opposite service an A record does
  • PTR records are usually set with your hosting provider. They are not part of your domain’s zone file.
  • An SOA record or Start of Authority record labels a zone file with the name of the host where it was originally created.
  • Minimum TTL: The minimum amount of time other servers should keep data cached from this zone file.
  • An SPF record or Sender Policy Framework record lists the designated mail servers for a domain or subdomain.
  • An SPF record for your domain tells other receiving mail servers which outgoing server(s) are valid sources of email so they can reject spoofed mail from your domain that has originated from unauthorized servers.
  • Make sure your SPF records are not too strict.
  • An SRV record or service record matches up a specific service that runs on your domain or subdomain to a target domain.
  • Service: The name of the service must be preceded by an underscore (_) and followed by a period (.)
  • Protocol: The name of the protocol must be proceeded by an underscore (_) and followed by a period (.)
  • Port: The TCP or UDP port on which the service runs.
  • Target: The target domain or subdomain. This domain must have an A or AAAA record that resolves to an IP address.
  • A TXT record or text record provides information about the domain in question to other resources on the internet.
  • 張 旭 on 28 Aug 19
     
    "Domain names are best understood by reading from right to left."
張 旭

Helm | - 0 views

helm.sh/using_helm

kubernetes helm system

shared by 張 旭 on 17 Jul 19 - No Cached
  • Helm will figure out where to install Tiller by reading your Kubernetes configuration file (usually $HOME/.kube/config). This is the same file that kubectl uses.
  • kubectl cluster-info
  • Role-Based Access Control (RBAC) enabled
  • ...133 more annotations...
  • initialize the local CLI
  • install Tiller into your Kubernetes cluster
  • helm install
  • helm init --upgrade
  • By default, when Tiller is installed, it does not have authentication enabled.
  • helm repo update
  • Without a max history set the history is kept indefinitely, leaving a large number of records for helm and tiller to maintain.
  • helm init --upgrade
  • Whenever you install a chart, a new release is created.
  • one chart can be installed multiple times into the same cluster. And each can be independently managed and upgraded.
  • helm list function will show you a list of all deployed releases.
  • helm delete
  • helm status
  • you can audit a cluster’s history, and even undelete a release (with helm rollback).
  • the Helm server (Tiller).
  • The Helm client (helm)
  • brew install kubernetes-helm
  • Tiller, the server portion of Helm, typically runs inside of your Kubernetes cluster.
  • it can also be run locally, and configured to talk to a remote Kubernetes cluster.
  • Role-Based Access Control - RBAC for short
  • create a service account for Tiller with the right roles and permissions to access resources.
  • run Tiller in an RBAC-enabled Kubernetes cluster.
  • run kubectl get pods --namespace kube-system and see Tiller running.
  • helm inspect
  • Helm will look for Tiller in the kube-system namespace unless --tiller-namespace or TILLER_NAMESPACE is set.
  • For development, it is sometimes easier to work on Tiller locally, and configure it to connect to a remote Kubernetes cluster.
  • even when running locally, Tiller will store release configuration in ConfigMaps inside of Kubernetes.
  • helm version should show you both the client and server version.
  • Tiller stores its data in Kubernetes ConfigMaps, you can safely delete and re-install Tiller without worrying about losing any data.
  • helm reset
  • The --node-selectors flag allows us to specify the node labels required for scheduling the Tiller pod.
  • --override allows you to specify properties of Tiller’s deployment manifest.
  • helm init --override manipulates the specified properties of the final manifest (there is no “values” file).
  • The --output flag allows us skip the installation of Tiller’s deployment manifest and simply output the deployment manifest to stdout in either JSON or YAML format.
  • By default, tiller stores release information in ConfigMaps in the namespace where it is running.
  • switch from the default backend to the secrets backend, you’ll have to do the migration for this on your own.
  • a beta SQL storage backend that stores release information in an SQL database (only postgres has been tested so far).
  • Once you have the Helm Client and Tiller successfully installed, you can move on to using Helm to manage charts.
  • Helm requires that kubelet have access to a copy of the socat program to proxy connections to the Tiller API.
  • A Release is an instance of a chart running in a Kubernetes cluster. One chart can often be installed many times into the same cluster.
  • helm init --client-only
  • helm init --dry-run --debug
  • A panic in Tiller is almost always the result of a failure to negotiate with the Kubernetes API server
  • Tiller and Helm have to negotiate a common version to make sure that they can safely communicate without breaking API assumptions
  • helm delete --purge
  • Helm stores some files in $HELM_HOME, which is located by default in ~/.helm
  • A Chart is a Helm package. It contains all of the resource definitions necessary to run an application, tool, or service inside of a Kubernetes cluster.
  • it like the Kubernetes equivalent of a Homebrew formula, an Apt dpkg, or a Yum RPM file.
  • A Repository is the place where charts can be collected and shared.
  • Set the $HELM_HOME environment variable
  • each time it is installed, a new release is created.
  • Helm installs charts into Kubernetes, creating a new release for each installation. And to find new charts, you can search Helm chart repositories.
  • chart repository is named stable by default
  • helm search shows you all of the available charts
  • helm inspect
  • To install a new package, use the helm install command. At its simplest, it takes only one argument: The name of the chart.
  • If you want to use your own release name, simply use the --name flag on helm install
  • additional configuration steps you can or should take.
  • Helm does not wait until all of the resources are running before it exits. Many charts require Docker images that are over 600M in size, and may take a long time to install into the cluster.
  • helm status
  • helm inspect values
  • helm inspect values stable/mariadb
  • override any of these settings in a YAML formatted file, and then pass that file during installation.
  • helm install -f config.yaml stable/mariadb
  • --values (or -f): Specify a YAML file with overrides.
  • --set (and its variants --set-string and --set-file): Specify overrides on the command line.
  • Values that have been --set can be cleared by running helm upgrade with --reset-values specified.
  • Chart designers are encouraged to consider the --set usage when designing the format of a values.yaml file.
  • --set-file key=filepath is another variant of --set. It reads the file and use its content as a value.
  • inject a multi-line text into values without dealing with indentation in YAML.
  • An unpacked chart directory
  • When a new version of a chart is released, or when you want to change the configuration of your release, you can use the helm upgrade command.
  • Kubernetes charts can be large and complex, Helm tries to perform the least invasive upgrade.
  • It will only update things that have changed since the last release
  • $ helm upgrade -f panda.yaml happy-panda stable/mariadb
  • deployment
  • If both are used, --set values are merged into --values with higher precedence.
  • The helm get command is a useful tool for looking at a release in the cluster.
  • helm rollback
  • A release version is an incremental revision. Every time an install, upgrade, or rollback happens, the revision number is incremented by 1.
  • helm history
  • a release name cannot be re-used.
  • you can rollback a deleted resource, and have it re-activate.
  • helm repo list
  • helm repo add
  • helm repo update
  • The Chart Development Guide explains how to develop your own charts.
  • helm create
  • helm lint
  • helm package
  • Charts that are archived can be loaded into chart repositories.
  • chart repository server
  • Tiller can be installed into any namespace.
  • Limiting Tiller to only be able to install into specific namespaces and/or resource types is controlled by Kubernetes RBAC roles and rolebindings
  • Release names are unique PER TILLER INSTANCE
  • Charts should only contain resources that exist in a single namespace.
  • not recommended to have multiple Tillers configured to manage resources in the same namespace.
  • a client-side Helm plugin. A plugin is a tool that can be accessed through the helm CLI, but which is not part of the built-in Helm codebase.
  • Helm plugins are add-on tools that integrate seamlessly with Helm. They provide a way to extend the core feature set of Helm, but without requiring every new feature to be written in Go and added to the core tool.
  • Helm plugins live in $(helm home)/plugins
  • The Helm plugin model is partially modeled on Git’s plugin model
  • helm referred to as the porcelain layer, with plugins being the plumbing.
  • helm plugin install https://github.com/technosophos/helm-template
  • command is the command that this plugin will execute when it is called.
  • Environment variables are interpolated before the plugin is executed.
  • The command itself is not executed in a shell. So you can’t oneline a shell script.
  • Helm is able to fetch Charts using HTTP/S
  • Variables like KUBECONFIG are set for the plugin if they are set in the outer environment.
  • In Kubernetes, granting a role to an application-specific service account is a best practice to ensure that your application is operating in the scope that you have specified.
  • restrict Tiller’s capabilities to install resources to certain namespaces, or to grant a Helm client running access to a Tiller instance.
  • Service account with cluster-admin role
  • The cluster-admin role is created by default in a Kubernetes cluster
  • Deploy Tiller in a namespace, restricted to deploying resources only in that namespace
  • Deploy Tiller in a namespace, restricted to deploying resources in another namespace
  • When running a Helm client in a pod, in order for the Helm client to talk to a Tiller instance, it will need certain privileges to be granted.
  • SSL Between Helm and Tiller
  • The Tiller authentication model uses client-side SSL certificates.
  • creating an internal CA, and using both the cryptographic and identity functions of SSL.
  • Helm is a powerful and flexible package-management and operations tool for Kubernetes.
  • default installation applies no security configurations
  • with a cluster that is well-secured in a private network with no data-sharing or no other users or teams.
  • With great power comes great responsibility.
  • Choose the Best Practices you should apply to your helm installation
  • Role-based access control, or RBAC
  • Tiller’s gRPC endpoint and its usage by Helm
  • Kubernetes employ a role-based access control (or RBAC) system (as do modern operating systems) to help mitigate the damage that can be done if credentials are misused or bugs exist.
  • In the default installation the gRPC endpoint that Tiller offers is available inside the cluster (not external to the cluster) without authentication configuration applied.
  • Tiller stores its release information in ConfigMaps. We suggest changing the default to Secrets.
  • release information
  • charts
  • charts are a kind of package that not only installs containers you may or may not have validated yourself, but it may also install into more than one namespace.
  • As with all shared software, in a controlled or shared environment you must validate all software you install yourself before you install it.
  • Helm’s provenance tools to ensure the provenance and integrity of charts
  • 張 旭 on 17 Jul 19
     
    "Helm will figure out where to install Tiller by reading your Kubernetes configuration file (usually $HOME/.kube/config). This is the same file that kubectl uses."
張 旭

What is a CAA record? - DNSimple Help - 0 views

support.dnsimple.com/...caa-record

networking network dns

shared by 張 旭 on 10 Mar 20 - No Cached
  • The purpose of the CAA record is to allow domain owners to declare which certificate authorities are allowed to issue a certificate for a domain.
  • If a CAA record is present, only the CAs listed in the record(s) are allowed to issue certificates for that hostname.
  • CAA records can set policy for the entire domain, or for specific hostnames.
  • ...4 more annotations...
  • The CAA record consists of a flags byte and a tag-value pair referred to as a ‘property’.
  • example.com. CAA 0 issue "letsencrypt.org"
  • each CAA record contains only one tag-value pair
  • dig google.com type257
張 旭

AskF5 | Manual Chapter: Working with Partitions - 0 views

techdocs.f5.com/...8.html

bigip network

shared by 張 旭 on 05 May 20 - No Cached
  • During BIG-IP® system installation, the system automatically creates a partition named Common
  • An administrative partition is a logical container that you create, containing a defined set of BIG-IP® system objects.
  • No user can delete partition Common itself.
  • ...9 more annotations...
  • With respect to permissions, all users on the system except those with a user role of No Access have read access to objects in partition Common, and by default, partition Common is their current partition.
  • The current partition is the specific partition to which the system is currently set for a logged-in user.
  • A partition access assignment gives a user some level of access to the specified partition.
  • assigning partition access to a user does not necessarily give the user full access to all objects in the partition
  • user account objects also reside in partitions
  • when you first install the BIG-IP system, every existing user account (root and admin) resides in partition Common
  • the partition in which a user account object resides does not affect the partition or partitions to which that user is granted access to manage other BIG-IP objects
  • the object it references resides in partition Common
  • a referenced object must reside either in the same partition as the object that is referencing it
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 20.2 Introducing InnoDB Cluster - 0 views

dev.mysql.com/...nodb-cluster-introduction.html

mysql cluster database HA

shared by 張 旭 on 19 Mar 17 - No Cached
  • A group of MySQL servers can be configured to create a cluster using MySQL Shell
  • The cluster of servers has a single master, called the primary, which acts as the read-write master.
  • Multiple secondary servers are replicas of the master
  • ...6 more annotations...
  • A client application is connected to the primary via MySQL Router
  • MySQL Shell also requires Python 2.7 and above to run cluster provisioning scripts
  • AdminAPI, which enables you to create and administer an InnoDB cluster, using either JavaScript or Python scripting
  • Caches the metadata of the InnoDB cluster and performs high availability routing to the MySQL Server instances which make up the cluster
  • Group Replication mechanism to allow data to be replicated from the primary to the secondaries in the cluster
  • AdminAPI is available as of MySQL Shell 1.0.8.
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 20.4 Getting Started with InnoDB Cluster - 0 views

dev.mysql.com/...b-cluster-getting-started.html

mysql cluster HA router database

shared by 張 旭 on 19 Mar 17 - No Cached
  • InnoDB cluster instances are created and managed through the MySQL Shell.
  • To create a new InnoDB cluster, the MySQL Shell must be connected to the MySQL Server instance. By default, this MySQL Server instance is the seed instance of the new InnoDB cluster and hold the initial data set.
  • Sandbox instance are only suitable for deploying and running on your local machine.
  • ...3 more annotations...
  • A minimum of three instances are required to create an InnoDB cluster
  • reverts to read-only mode
  • MySQL Shell provides two scripting languages: JavaScript and Python.
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 19.1 Group Replication Background - 0 views

dev.mysql.com/...up-replication-background.html

mysql cluster HA system database replication

shared by 張 旭 on 19 Mar 17 - No Cached
  • the component can be removed and the system should continue to operate as expected
  • network partitioning
  • split brain scenarios
  • ...8 more annotations...
  • the ultimate challenge is to fuse the logic of the database and data replication with the logic of having several servers coordinated in a consistent and simple way
  • MySQL Group Replication provides distributed state machine replication with strong coordination between servers.
  • Servers coordinate themselves automatically when they are part of the same group
  • The group can operate in a single-primary mode with automatic primary election, where only one server accepts updates at a time.
  • For a transaction to commit, the majority of the group have to agree on the order of a given transaction in the global sequence of transactions
  • Deciding to commit or abort a transaction is done by each server individually, but all servers make the same decision
  • group communication protocols
  • the Paxos algorithm. It acts as the group communication systems engine.
張 旭

MySQL :: MySQL 5.7 Reference Manual :: 19.1.1.2 Group Replication - 0 views

dev.mysql.com/...group-replication-summary.html

mysql HA system database replication

shared by 張 旭 on 19 Mar 17 - No Cached
  • The replication group is a set of servers that interact with each other through message passing.
  • The communication layer provides a set of guarantees such as atomic message and total order message delivery.
  • a multi-master update everywhere replication protocol
  • ...8 more annotations...
  • a replication group is formed by multiple servers and each server in the group may execute transactions independently
  • Read-only (RO) transactions need no coordination within the group and thus commit immediately
  • any RW transaction the group needs to decide whether it commits or not, thus the commit operation is not a unilateral decision from the originating server
  • when a transaction is ready to commit at the originating server, the server atomically broadcasts the write values (rows changed) and the correspondent write set (unique identifiers of the rows that were updated). Then a global total order is established for that transaction.
  • all servers receive the same set of transactions in the same order
  • The resolution procedure states that the transaction that was ordered first commits on all servers, whereas the transaction ordered second aborts, and thus is rolled back on the originating server and dropped by the other servers in the group. This is in fact a distributed first commit wins rule
  • Group Replication is a shared-nothing replication scheme where each server has its own entire copy of the data
  • MySQL Group Replication protocol
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

Automated Nginx Reverse Proxy for Docker - 0 views

jasonwilder.com/...nginx-reverse-proxy-for-docker

docker nginx proxy haproxy system web server

shared by 張 旭 on 04 Dec 15 - No Cached
  • Docker containers are assigned random IPs and ports which makes addressing them much more complicated from a client perspsective
  • Binding the container to the hosts port can prevent multiple containers from running on the same host. For example, only one container can bind to port 80 at a time.
  • Docker provides a remote API to inspect containers and access their IP, Ports and other configuration meta-data.
  • ...1 more annotation...
  • nginx template can be used to generate a reverse proxy configuration for docker containers using virtual hosts for routing.
張 旭

Introduction to MongoDB - MongoDB Manual - 0 views

docs.mongodb.com/...introduction

database mongodb

shared by 張 旭 on 20 Apr 21 - No Cached
  • MongoDB is a document database designed for ease of development and scaling
  • MongoDB offers both a Community and an Enterprise version
  • A record in MongoDB is a document, which is a data structure composed of field and value pairs.
  • ...12 more annotations...
  • MongoDB documents are similar to JSON objects.
  • The values of fields may include other documents, arrays, and arrays of documents.
  • reduce need for expensive joins
  • MongoDB stores documents in collections.
  • Collections are analogous to tables in relational databases.
  • Read-only Views
  • Indexes support faster queries and can include keys from embedded documents and arrays.
  • MongoDB's replication facility, called replica set
  • A replica set is a group of MongoDB servers that maintain the same data set, providing redundancy and increasing data availability.
  • Sharding distributes data across a cluster of machines.
  • MongoDB supports creating zones of data based on the shard key.
  • MongoDB provides pluggable storage engine API
張 旭

Custom Resources | Kubernetes - 0 views

kubernetes.io/...custom-resources

kubernetes

shared by 張 旭 on 11 May 21 - No Cached
  • Custom resources are extensions of the Kubernetes API
  • A resource is an endpoint in the Kubernetes API that stores a collection of API objects of a certain kind
  • Custom resources can appear and disappear in a running cluster through dynamic registration
  • ...30 more annotations...
  • Once a custom resource is installed, users can create and access its objects using kubectl
  • When you combine a custom resource with a custom controller, custom resources provide a true declarative API.
  • A declarative API allows you to declare or specify the desired state of your resource and tries to keep the current state of Kubernetes objects in sync with the desired state.
  • Custom controllers can work with any kind of resource, but they are especially effective when combined with custom resources.
  • The Operator pattern combines custom resources and custom controllers.
  • the API represents a desired state, not an exact state.
  • define configuration of applications or infrastructure.
  • The main operations on the objects are CRUD-y (creating, reading, updating and deleting).
  • The client says "do this", and then gets an operation ID back, and has to check a separate Operation object to determine completion of the request.
  • The natural operations on the objects are not CRUD-y.
  • High bandwidth access (10s of requests per second sustained) needed.
  • Use a ConfigMap if any of the following apply
  • You want to put the entire config file into one key of a configMap.
  • You want to perform rolling updates via Deployment, etc., when the file is updated.
  • Use a secret for sensitive data, which is similar to a configMap but more secure.
  • You want to build new automation that watches for updates on the new object, and then CRUD other objects, or vice versa.
  • You want the object to be an abstraction over a collection of controlled resources, or a summarization of other resources.
  • CRDs are simple and can be created without any programming.
  • Aggregated APIs are subordinate API servers that sit behind the primary API server
  • CRDs allow users to create new types of resources without adding another API server
  • Defining a CRD object creates a new custom resource with a name and schema that you specify.
  • The name of a CRD object must be a valid DNS subdomain name
  • each resource in the Kubernetes API requires code that handles REST requests and manages persistent storage of objects.
  • The main API server delegates requests to you for the custom resources that you handle, making them available to all of its clients.
  • The new endpoints support CRUD basic operations via HTTP and kubectl
  • Custom resources consume storage space in the same way that ConfigMaps do.
  • Aggregated API servers may use the same storage as the main API server
  • CRDs always use the same authentication, authorization, and audit logging as the built-in resources of your API server.
  • most RBAC roles will not grant access to the new resources (except the cluster-admin role or any role created with wildcard rules).
  • CRDs and Aggregated APIs often come bundled with new role definitions for the types they add.
張 旭

Configuration Blocks and Attributes - 0 views

terragrunt.gruntwork.io/...config-blocks-and-attributes

terraform devops

shared by 張 旭 on 16 Jun 21 - No Cached
  • The generate block can be used to arbitrarily generate a file in the terragrunt working directory (where terraform is called).
  • This can be used to generate common terraform configurations that are shared across multiple terraform modules.
  • 張 旭 on 16 Jun 21
     
    "The generate block can be used to arbitrarily generate a file in the terragrunt working directory (where terraform is called). "
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