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crazylion lee

Apache Geode (incubating) | Home - 0 views

geode.incubator.apache.org

apache in-memory db

shared by crazylion lee on 30 Nov 15 - No Cached
  • crazylion lee on 30 Nov 15
     
    "Geode is an open source, distributed, in-memory database for scale-out applications."
張 旭

The Twelve-Factor App - 0 views

12factor.net/codebase

development programming system software

shared by 張 旭 on 01 Jan 19 - No Cached
  • A copy of the revision tracking database is known as a code repository, often shortened to code repo or just repo.
  • always a one-to-one correlation between the codebase and the app
  • If there are multiple codebases, it’s not an app – it’s a distributed system.
  • ...4 more annotations...
  • Each component in a distributed system is an app
  • only one codebase per app, but there will be many deploys of the app.
  • A deploy is a running instance of the app.
  • The codebase is the same across all deploys, although different versions may be active in each deploy.
  • 張 旭 on 01 Jan 19
     
    "A copy of the revision tracking database is known as a code repository, often shortened to code repo or just repo."
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

MongoDB Performance Tuning: Everything You Need to Know - Stackify - 0 views

stackify.com/mongodb-performance-tuning

database mongodb

shared by 張 旭 on 15 Apr 21 - No Cached
  • db.serverStatus().globalLock
  • db.serverStatus().locks
  • globalLock.currentQueue.total: This number can indicate a possible concurrency issue if it’s consistently high. This can happen if a lot of requests are waiting for a lock to be released.
  • ...35 more annotations...
  • globalLock.totalTime: If this is higher than the total database uptime, the database has been in a lock state for too long.
  • Unlike relational databases such as MySQL or PostgreSQL, MongoDB uses JSON-like documents for storing data.
  • Databases operate in an environment that consists of numerous reads, writes, and updates.
  • When a lock occurs, no other operation can read or modify the data until the operation that initiated the lock is finished.
  • locks.deadlockCount: Number of times the lock acquisitions have encountered deadlocks
  • Is the database frequently locking from queries? This might indicate issues with the schema design, query structure, or system architecture.
  • For version 3.2 on, WiredTiger is the default.
  • MMAPv1 locks whole collections, not individual documents.
  • WiredTiger performs locking at the document level.
  • When the MMAPv1 storage engine is in use, MongoDB will use memory-mapped files to store data.
  • All available memory will be allocated for this usage if the data set is large enough.
  • db.serverStatus().mem
  • mem.resident: Roughly equivalent to the amount of RAM in megabytes that the database process uses
  • If mem.resident exceeds the value of system memory and there’s a large amount of unmapped data on disk, we’ve most likely exceeded system capacity.
  • If the value of mem.mapped is greater than the amount of system memory, some operations will experience page faults.
  • The WiredTiger storage engine is a significant improvement over MMAPv1 in performance and concurrency.
  • By default, MongoDB will reserve 50 percent of the available memory for the WiredTiger data cache.
  • wiredTiger.cache.bytes currently in the cache – This is the size of the data currently in the cache.
  • wiredTiger.cache.tracked dirty bytes in the cache – This is the size of the dirty data in the cache.
  • we can look at the wiredTiger.cache.bytes read into cache value for read-heavy applications. If this value is consistently high, increasing the cache size may improve overall read performance.
  • check whether the application is read-heavy. If it is, increase the size of the replica set and distribute the read operations to secondary members of the set.
  • write-heavy, use sharding within a sharded cluster to distribute the load.
  • Replication is the propagation of data from one node to another
  • Replication sets handle this replication.
  • Sometimes, data isn’t replicated as quickly as we’d like.
  • a particularly thorny problem if the lag between a primary and secondary node is high and the secondary becomes the primary
  • use the db.printSlaveReplicationInfo() or the rs.printSlaveReplicationInfo() command to see the status of a replica set from the perspective of the secondary member of the set.
  • shows how far behind the secondary members are from the primary. This number should be as low as possible.
  • monitor this metric closely.
  • watch for any spikes in replication delay.
  • Always investigate these issues to understand the reasons for the lag.
  • One replica set is primary. All others are secondary.
  • it’s not normal for nodes to change back and forth between primary and secondary.
  • use the profiler to gain a deeper understanding of the database’s behavior.
  • Enabling the profiler can affect system performance, due to the additional activity.
  • 張 旭 on 15 Apr 21
     
    "globalLock.currentQueue.total: This number can indicate a possible concurrency issue if it's consistently high. This can happen if a lot of requests are waiting for a lock to be released."
張 旭

Options for Highly Available Topology | Kubernetes - 0 views

kubernetes.io/...ha-topology

kubernetes etcd

shared by 張 旭 on 26 Jan 23 - No Cached
  • With stacked control plane nodes, where etcd nodes are colocated with control plane nodes
  • A stacked HA cluster is a topology where the distributed data storage cluster provided by etcd is stacked on top of the cluster formed by the nodes managed by kubeadm that run control plane components.
  • Each control plane node runs an instance of the kube-apiserver, kube-scheduler, and kube-controller-manager
  • ...6 more annotations...
  • Each control plane node creates a local etcd member and this etcd member communicates only with the kube-apiserver of this node.
  • This topology couples the control planes and etcd members on the same nodes.
  • a stacked cluster runs the risk of failed coupling. If one node goes down, both an etcd member and a control plane instance are lost
  • An HA cluster with external etcd is a topology where the distributed data storage cluster provided by etcd is external to the cluster formed by the nodes that run control plane components.
  • etcd members run on separate hosts, and each etcd host communicates with the kube-apiserver of each control plane node.
  • This topology decouples the control plane and etcd member. It therefore provides an HA setup where losing a control plane instance or an etcd member has less impact and does not affect the cluster redundancy as much as the stacked HA topology.
crazylion lee

Home - SemiCode OS - 0 views

www.semicodeos.com

linux programmer distribution

shared by crazylion lee on 04 Dec 16 - No Cached
  • crazylion lee on 04 Dec 16
     
    "SemiCode OS - Linux For Programmers and Web Developers"
crazylion lee

twitter/distributedlog: A high performance replicated log service. - 0 views

github.com/...distributedlog

twitter log distributed

shared by crazylion lee on 26 Jun 16 - No Cached
  • crazylion lee on 26 Jun 16
     
    "A high performance replicated log service. http://distributedlog.io"
張 旭

How to write excellent Dockerfiles - 0 views

rock-it.pl/to-write-excellent-dockerfiles

docker server system

shared by 張 旭 on 10 Apr 17 - No Cached
  • minimize image size, build time and number of layers.
  • maximize build cache usage
  • Container should do one thing
    • 張 旭
      張 旭 on 10 Apr 17
       
      這個有待商榷，在 baseimage 的 blog 介紹中有詳細的討論。
  • ...25 more annotations...
  • Use COPY and RUN commands in proper order
  • Merge multiple RUN commands into one
  • alpine versions should be enough
  • Use exec inside entrypoint script
  • Prefer COPY over ADD
  • Specify default environment variables, ports and volumes inside Dockerfile
  • problems with zombie processes
  • prepare separate Docker image for each component, and use Docker Compose to easily start multiple containers at the same time
  • Layers are cached and reused
  • Layers are immutable
  • They both makes you cry
  • rely on our base image updates
  • make a cleanup
  • alpine is a very tiny linux distribution, just about 4 MB in size.
  • Your disk will love you :)
  • WORKDIR command changes default directory, where we run our RUN / CMD / ENTRYPOINT commands.
  • CMD is a default command run after creating container without other command specified.
  • put your command inside array
  • entrypoint adds complexity
  • Entrypoint is a script, that will be run instead of command, and receive command as arguments
  • Without it, we would not be able to stop our application grecefully (SIGTERM is swallowed by bash script).
  • Use "exec" inside entrypoint script
  • ADD has some logic for downloading remote files and extracting archives.
  • stick with COPY.
  • ADD
    • 張 旭
      張 旭 on 10 Apr 17
       
      不是說要用 COPY 嗎？
張 旭

javascript - How do I "think in AngularJS" if I have a jQuery background? - Stack Overflow - 0 views

stackoverflow.com/...-if-i-have-a-jquery-background

jquery javascript angular programming architecture development google angularjs web

shared by 張 旭 on 02 Oct 13 - No Cached
  • in AngularJS, we have a separate model layer that we can manage in any way we want, completely independently from the view.
  • keep your concerns separate
  • do DOM manipulation and augment your view with directives
  • ...34 more annotations...
  • DI means that you can declare components very freely and then from any other component, just ask for an instance of it and it will be granted
  • do test-driven development iteratively in AngularJS!
  • only do DOM manipulation in a directive
  • with ngClass we can dynamically update the class;
  • ngBind allows two-way data binding;
  • ngShow and ngHide programmatically show or hide an element;
  • The less DOM manipulation, the easier directives are to test, the easier they are to style, the easier they are to change in the future, and the more re-usable and distributable they are.
  • still wrong.
  • Before doing DOM manipulation anywhere in your application, ask yourself if you really need to.
  • a few things wrong with this
  • jQuery was never necessary
  • use angular.element and our component will still work when dropped into a project that doesn't have jQuery.
  • just use angular.element
  • the element that is passed to the link function would already be a jQuery element!
  • directives aren't just collections of jQuery-like functions
  • Directives are actually extensions of HTML
  • If HTML doesn't do something you need it to do, you write a directive to do it for you, and then use it just as if it was part of HTML.
  • think how the team would accomplish it to fit right in with ngClick, ngClass, et al.
  • Don't even use jQuery. Don't even include it.
  • ry to think about how to do it within the confines the AngularJS.
  • In jQuery, selectors are used to find DOM elements and then bind/register event handlers to them.
  • Views are (declarative) HTML that contain AngularJS directives
  • Directives set up the event handlers behind the scenes for us and give us dynamic databinding.
  • Views are tied to models (via scopes). Views are a projection of the model
  • In AngularJS, think about models, rather than jQuery-selected DOM elements that hold your data.
  • AngularJS uses controllers and directives (each of which can have their own controller, and/or compile and linking functions) to remove behavior from the view/structure (HTML). Angular also has services and filters to help separate/organize your application.
  • Think about your models
  • Think about how you want to present your models -- your views.
  • using the necessary directives to get dynamic databinding.
  • Attach a controller to each view (using ng-view and routing, or ng-controller)
  • Make controllers as thin as possible.
  • You can do a lot with jQuery without knowing about how JavaScript prototypal inheritance works.
  • jQuery is a library
  • AngularJS is a beautiful client-side framework
張 旭

How to Use Docker on OS X: The Missing Guide | Viget - 0 views

viget.com/...cker-on-os-x-the-missing-guide

docker mac system deploy

shared by 張 旭 on 25 Oct 14 - No Cached
  • Docker is a client-server application.
  • The Docker server is a daemon that does all the heavy lifting: building and downloading images, starting and stopping containers, and the like. It exposes a REST API for remote management.
  • The Docker client is a command line program that communicates with the Docker server using the REST API.
  • ...9 more annotations...
  • interact with Docker by using the client to send commands to the server.
  • The machine running the Docker server is called the Docker host
  • Docker uses features only available to Linux, that machine must be running Linux (more specifically, the Linux kernel).
  • boot2docker is a “lightweight Linux distribution made specifically to run Docker containers.”
  • Docker server will run inside our boot2docker VM
  • boot2docker, not OS X, is the Docker host, not OS X.
  • Docker mounts volumes from the boot2docker VM, not from OS X
  • initialize boot2docker (we only have to do this once):
  • The Docker client assumes the Docker host is the current machine. We need to tell it to use our boot2docker VM by setting the DOCKER_HOST environment variable
crazylion lee

Tails - Privacy for anyone anywhere - 1 views

tails.boum.org/index.en.html

privacy linux security distribution

shared by crazylion lee on 21 Nov 15 - No Cached
  • crazylion lee on 21 Nov 15
     
    "Tails is a live operating system, that you can start on almost any computer from a DVD, USB stick, or SD card. It aims at preserving your privacy and anonymity, and helps you to: "
張 旭

Flynn: first preview release | Hacker News - 0 views

news.ycombinator.com/item

docker consul system service discovery dns

shared by 張 旭 on 25 Nov 15 - No Cached
  • Etcd and Zookeeper provide essentially the same functionality. They are both a strongly consistent key/value stores that support notifications to clients of changes. These two projects are limited to service discovery
  • So lets say you had a client application that would talk to a node application that could be on any number of servers. What you could do is hard code that list into your application and randomly select one, in order to "fake" load balancing. However every time a machine went up or down you would have to update that list.
  • What Consul provides is you just tell your app to connect to "mynodeapp.consul" and then consul will give you the proper address of one of your node apps.
  • ...9 more annotations...
  • Consul and Skydock are both applications that build on top of a tool like Zookeeper and Etcd.
  • What a developer ideally wants to do is just push code and not have to worry about what servers are running what, and worry about failover and the like
  • What Flynn provides (if I get it), is a diy Heroku like platform
  • Raft is a consensus algorithm for keeping a set of distributed state machines in a consistent state.
  • a self hosted Heroku
  • Google Omega is Google's answer to Apache Mesos
  • Omega would need a service like Raft to understand what services are currently available
  • Another project that I believe may be similar to Flynn is Apache Mesos.
  • I want to use Docker, but it has no easy way to say "take this file that contains instructions and make everything". You can write Dockerfiles, but you can only use one part of the stack in them, otherwise you run into trouble.
  • 張 旭 on 25 Nov 15
     
    " So lets say you had a client application that would talk to a node application that could be on any number of servers. What you could do is hard code that list into your application and randomly select one, in order to "fake" load balancing. However every time a machine went up or down you would have to update that list. What Consul provides is you just tell your app to connect to "mynodeapp.consul" and then consul will give you the proper address of one of your node apps."
張 旭

Virtual Private Cloud (VPC)  |  Virtual Private Cloud  |  Google Cloud - 0 views

cloud.google.com/vpc

google gcp cloud system

shared by 張 旭 on 09 Nov 18 - No Cached
  • A single Google Cloud VPC can span multiple regions without communicating across the public Internet.
  • Google Cloud VPCs let you increase the IP space of any subnets without any workload shutdown or downtime.
  • Get private access to Google services, such as storage, big data, analytics, or machine learning, without having to give your service a public IP address.
  • ...3 more annotations...
  • Enable dynamic Border Gateway Protocol (BGP) route updates between your VPC network and your non-Google network with our virtual router.
  • Configure a VPC Network to be shared across several projects in your organization.
  • Hosting globally distributed multi-tier applications, by creating a VPC with subnets.
張 旭

10 Common Git Problems and How to Fix Them - DEV Community - 0 views

dev.to/...blems-and-how-to-fix-them-234o

git

shared by 張 旭 on 03 Sep 18 - No Cached
  • Please keep in mind that --amend actually will create a new commit which replaces the previous one, so don’t use it for modifying commits which already have been pushed to a central repository.
  • git rebase --interactive
  • Just pick the commit(s) you want to update, change pick to reword (or r for short), and you will be taken to a new view where you can edit the message.
  • ...8 more annotations...
  • you can completely remove commits by deleting them from the list, as well as edit, reorder, and squash them.
  • Squashing allows you to merge several commits into one
  • In case you don’t want to create additional revert commits but only apply the necessary changes to your working tree, you can use the --no-commit/-n option.
  • reuse recorded resolution
  • Unfortunately it turns out that one of the branches isn’t quite there yet, so you decide to un-merge it again. Several days (or weeks) later when the branch is finally ready you merge it again, but thanks to the recorded resolutions, you won’t have to resolve the same merge conflicts again.
  • You can also define global hooks to use in all your projects by creating a template directory that git will use when initializing a new repository
  • removing sensitive data
  • Keep in mind that this will rewrite your project’s entire history, which can be very disruptive in a distributed workflow.
張 旭

Deploy a registry server | Docker Documentation - 0 views

docs.docker.com/...deploying

docker system

shared by 張 旭 on 06 Sep 18 - No Cached
  • By default, secrets are mounted into a service at /run/secrets/<secret-name>
  • docker secret create
  • If you use a distributed storage driver, such as Amazon S3, you can use a fully replicated service. Each worker can write to the storage back-end without causing write conflicts.
  • ...10 more annotations...
  • You can access the service on port 443 of any swarm node. Docker sends the requests to the node which is running the service.
  • --publish published=443,target=443
  • The most important aspect is that a load balanced cluster of registries must share the same resources
  • S3 or Azure, they should be accessing the same resource and share an identical configuration.
  • you must make sure you are properly sending the X-Forwarded-Proto, X-Forwarded-For, and Host headers to their “client-side” values. Failure to do so usually makes the registry issue redirects to internal hostnames or downgrading from https to http.
  • A properly secured registry should return 401 when the “/v2/” endpoint is hit without credentials
  • registries should always implement access restrictions.
  • REGISTRY_AUTH=htpasswd
  • REGISTRY_AUTH_HTPASSWD_PATH=/auth/htpasswd
  • The registry also supports delegated authentication which redirects users to a specific trusted token server. This approach is more complicated to set up, and only makes sense if you need to fully configure ACLs and need more control over the registry’s integration into your global authorization and authentication systems.
  • 張 旭 on 06 Sep 18
     
    "You can access the service on port 443 of any swarm node. Docker sends the requests to the node which is running the service. "
張 旭

Boosting your kubectl productivity ♦︎ Learnk8s - 0 views

learnk8s.io/...kubectl-productivity

devops kubernetes kubectl

shared by 張 旭 on 09 Apr 19 - No Cached
  • kubectl is your cockpit to control Kubernetes.
  • kubectl is a client for the Kubernetes API
  • Kubernetes API is an HTTP REST API.
  • ...75 more annotations...
  • This API is the real Kubernetes user interface.
  • Kubernetes is fully controlled through this API
  • every Kubernetes operation is exposed as an API endpoint and can be executed by an HTTP request to this endpoint.
  • the main job of kubectl is to carry out HTTP requests to the Kubernetes API
  • Kubernetes maintains an internal state of resources, and all Kubernetes operations are CRUD operations on these resources.
  • Kubernetes is a fully resource-centred system
  • Kubernetes API reference is organised as a list of resource types with their associated operations.
  • This is how kubectl works for all commands that interact with the Kubernetes cluster.
  • kubectl simply makes HTTP requests to the appropriate Kubernetes API endpoints.
  • it's totally possible to control Kubernetes with a tool like curl by manually issuing HTTP requests to the Kubernetes API.
  • Kubernetes consists of a set of independent components that run as separate processes on the nodes of a cluster.
  • components on the master nodes
  • Storage backend: stores resource definitions (usually etcd is used)
  • API server: provides Kubernetes API and manages storage backend
  • Controller manager: ensures resource statuses match specifications
  • Scheduler: schedules Pods to worker nodes
  • component on the worker nodes
  • Kubelet: manages execution of containers on a worker node
  • triggers the ReplicaSet controller, which is a sub-process of the controller manager.
  • the scheduler, who watches for Pod definitions that are not yet scheduled to a worker node.
  • creating and updating resources in the storage backend on the master node.
  • The kubelet of the worker node your ReplicaSet Pods have been scheduled to instructs the configured container runtime (which may be Docker) to download the required container images and run the containers.
  • Kubernetes components (except the API server and the storage backend) work by watching for resource changes in the storage backend and manipulating resources in the storage backend.
  • However, these components do not access the storage backend directly, but only through the Kubernetes API.
    • 張 旭
      張 旭 on 09 Apr 19
       
      很精彩，相互之間都是使用 API call 溝通，良好的微服務行為。
  • double usage of the Kubernetes API for internal components as well as for external users is a fundamental design concept of Kubernetes.
  • All other Kubernetes components and users read, watch, and manipulate the state (i.e. resources) of Kubernetes through the Kubernetes API
  • The storage backend stores the state (i.e. resources) of Kubernetes.
  • command completion is a shell feature that works by the means of a completion script.
  • A completion script is a shell script that defines the completion behaviour for a specific command. Sourcing a completion script enables completion for the corresponding command.
  • kubectl completion zsh
  • /etc/bash_completion.d directory (create it, if it doesn't exist)
  • source <(kubectl completion bash)
  • source <(kubectl completion zsh)
  • autoload -Uz compinit compinit
  • the API reference, which contains the full specifications of all resources.
  • kubectl api-resources
  • displays the resource names in their plural form (e.g. deployments instead of deployment). It also displays the shortname (e.g. deploy) for those resources that have one. Don't worry about these differences. All of these name variants are equivalent for kubectl.
  • .spec
  • custom columns output format comes in. It lets you freely define the columns and the data to display in them. You can choose any field of a resource to be displayed as a separate column in the output
  • kubectl get pods -o custom-columns='NAME:metadata.name,NODE:spec.nodeName'
  • kubectl explain pod.spec.
  • kubectl explain pod.metadata.
  • browse the resource specifications and try it out with any fields you like!
  • JSONPath is a language to extract data from JSON documents (it is similar to XPath for XML).
  • with kubectl explain, only a subset of the JSONPath capabilities is supported
  • Many fields of Kubernetes resources are lists, and this operator allows you to select items of these lists. It is often used with a wildcard as [*] to select all items of the list.
  • kubectl get pods -o custom-columns='NAME:metadata.name,IMAGES:spec.containers[*].image'
  • a Pod may contain more than one container.
  • The availability zones for each node are obtained through the special failure-domain.beta.kubernetes.io/zone label.
  • kubectl get nodes -o yaml kubectl get nodes -o json
  • The default kubeconfig file is ~/.kube/config
  • with multiple clusters, then you have connection parameters for multiple clusters configured in your kubeconfig file.
  • Within a cluster, you can set up multiple namespaces (a namespace is kind of "virtual" clusters within a physical cluster)
  • overwrite the default kubeconfig file with the --kubeconfig option for every kubectl command.
  • Namespace: the namespace to use when connecting to the cluster
  • a one-to-one mapping between clusters and contexts.
  • When kubectl reads a kubeconfig file, it always uses the information from the current context.
  • just change the current context in the kubeconfig file
  • to switch to another namespace in the same cluster, you can change the value of the namespace element of the current context
  • kubectl also provides the --cluster, --user, --namespace, and --context options that allow you to overwrite individual elements and the current context itself, regardless of what is set in the kubeconfig file.
  • for switching between clusters and namespaces is kubectx.
  • kubectl config get-contexts
  • just have to download the shell scripts named kubectl-ctx and kubectl-ns to any directory in your PATH and make them executable (for example, with chmod +x)
  • kubectl proxy
  • kubectl get roles
  • kubectl get pod
  • Kubectl plugins are distributed as simple executable files with a name of the form kubectl-x. The prefix kubectl- is mandatory,
  • To install a plugin, you just have to copy the kubectl-x file to any directory in your PATH and make it executable (for example, with chmod +x)
  • krew itself is a kubectl plugin
  • check out the kubectl-plugins GitHub topic
  • The executable can be of any type, a Bash script, a compiled Go program, a Python script, it really doesn't matter. The only requirement is that it can be directly executed by the operating system.
  • kubectl plugins can be written in any programming or scripting language.
  • you can write more sophisticated plugins with real programming languages, for example, using a Kubernetes client library. If you use Go, you can also use the cli-runtime library, which exists specifically for writing kubectl plugins.
  • a kubeconfig file consists of a set of contexts
  • changing the current context means changing the cluster, if you have only a single context per cluster.
張 旭

Providers - Configuration Language - Terraform by HashiCorp - 0 views

www.terraform.io/...providers.html

terraform config devops

shared by 張 旭 on 11 Apr 19 - No Cached
  • By default, terraform init downloads plugins into a subdirectory of the working directory so that each working directory is self-contained.
  • Terraform optionally allows the use of a local directory as a shared plugin cache, which then allows each distinct plugin binary to be downloaded only once.
  • directory must already exist before Terraform will cache plugins; Terraform will not create the directory itself.
  • ...3 more annotations...
  • When a plugin cache directory is enabled, the terraform init command will still access the plugin distribution server to obtain metadata about which plugins are available, but once a suitable version has been selected it will first check to see if the selected plugin is already available in the cache directory.
  • When possible, Terraform will use hardlinks or symlinks to avoid storing a separate copy of a cached plugin in multiple directories.
  • Terraform will never itself delete a plugin from the plugin cache once it's been placed there.
  • 張 旭 on 11 Apr 19
     
    "By default, terraform init downloads plugins into a subdirectory of the working directory so that each working directory is self-contained."
張 旭

Scalable architecture without magic (and how to build it if you're not Google) - DEV Co... - 0 views

dev.to/...ld-it-if-youre-not-google-336a

development architecture system google

shared by 張 旭 on 24 Feb 19 - No Cached
  • Don’t mess up write-first and read-first databases.
  • keep them stateless.
  • you should know how to make a scalable setup on bare metal.
  • ...29 more annotations...
  • Different programming languages are for different tasks.
  • Go or C which are compiled to run on bare metal.
  • To run NodeJS on multiple cores, you have to use something like PM2, but since this you have to keep your code stateless.
  • Python have very rich and sugary syntax that’s great for working with data while keeping your code small and expressive.
  • SQL is almost always slower than NoSQL
  • databases are often read-first or write-first
  • write-first, just like Cassandra.
  • store all of your data to your databases and leave nothing at backend
  • Functional code is stateless by default
  • It’s better to go for stateless right from the very beginning.
  • deliver exactly the same responses for same requests.
  • Sessions? Store them at Redis and allow all of your servers to access it.
  • Only the first user will trigger a data query, and all others will be receiving exactly the same data straight from the RAM
  • never, never cache user input
  • Only the server output should be cached
  • Varnish is a great cache option that works with HTTP responses, so it may work with any backend.
  • a rate limiter – if there’s not enough time have passed since last request, the ongoing request will be denied.
  • different requests blasting every 10ms can bring your server down
  • Just set up entry relations and allow your database to calculate external keys for you
  • the query planner will always be faster than your backend.
  • Backend should have different responsibilities: hashing, building web pages from data and templates, managing sessions and so on.
  • For anything related to data management or data models, move it to your database as procedures or queries.
  • a distributed database.
  • your code has to be stateless
  • Move anything related to the data to the database.
  • For load-balancing a database, go for cluster.
  • DB is balancing requests, as well as your backend.
  • Users from different continents are separated with DNS.
  • Keep is scalable, keep is stateless.
  • 張 旭 on 24 Feb 19
     
    "Don't mess up write-first and read-first databases."
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