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張 旭

Baseimage-docker: A minimal Ubuntu base image modified for Docker-friendliness - 0 views

phusion.github.io/baseimage-docker

docker base system linux

shared by 張 旭 on 29 Oct 14 - No Cached
  • We encourage you to use multiple processes.
  • Baseimage-docker is a special Docker image that is configured for correct use within Docker containers.
  • When your Docker container starts, only the CMD command is run.
  • ...16 more annotations...
  • You're not running them, you're only running your app.
  • You have Ubuntu installed in Docker. The files are there. But that doesn't mean Ubuntu's running as it should.
  • The only processes that will be running inside the container is the CMD command, and all processes that it spawns.
  • A proper Unix system should run all kinds of important system services.
  • Ubuntu is not designed to be run inside Docker
  • When a system is started, the first process in the system is called the init process, with PID 1. The system halts when this processs halts.
  • Runit (written in C) is much lighter weight than supervisord (written in Python).
  • Docker runs fine with multiple processes in a container.
  • Baseimage-docker encourages you to run multiple processes through the use of runit.
  • If your init process is your app, then it'll probably only shut down itself, not all the other processes in the container.
  • a Docker container, which is a locked down environment with e.g. no direct access to many kernel resources.
  • Used for service supervision and management.
  • A custom tool for running a command as another user.
  • add additional daemons (e.g. your own app) to the image by creating runit entries.
  • write a small shell script which runs your daemon, and runit will keep it up and running for you, restarting it when it crashes, etc.
  • the shell script must run the daemon without letting it daemonize/fork it.
張 旭

An App's Brief Journey from Source to Image · Cloud Native Buildpack Document... - 0 views

buildpacks.io/app-journey

devops buildpacks package docker

shared by 張 旭 on 02 Aug 19 - No Cached
  • A buildpack’s job is to gather everything your app needs to build and run, and it often does this job quickly and quietly.
  • a platform sequentially tests groups of buildpacks against your app’s source code.
  • transforming your source code into a runnable app image.
  • ...2 more annotations...
  • Detection criteria is specific to each buildpack – for instance, an NPM buildpack might look for a package.json, and a Go buildpack might look for Go source files.
  • A builder is essentially an image containing buildpacks.
張 旭

phusion/passenger-docker: Docker base images for Ruby, Python, Node.js and Meteor web apps - 0 views

github.com/...passenger-docker

docker ruby rails

shared by 張 旭 on 14 Jan 22 - No Cached
  • Ubuntu 20.04 LTS as base system
  • 2.7.5 is configured as the default.
  • Python 3.8
  • ...23 more annotations...
  • A build system, git, and development headers for many popular libraries, so that the most popular Ruby, Python and Node.js native extensions can be compiled without problems.
  • Nginx 1.18. Disabled by default
  • production-grade features, such as process monitoring, administration and status inspection.
  • Redis 5.0. Not installed by default.
  • The image has an app user with UID 9999 and home directory /home/app. Your application is supposed to run as this user.
  • running applications without root privileges is good security practice.
  • Your application should be placed inside /home/app.
  • COPY --chown=app:app
  • Passenger works like a mod_ruby, mod_nodejs, etc. It changes Nginx into an application server and runs your app from Nginx.
  • placing a .conf file in the directory /etc/nginx/sites-enabled
  • The best way to configure Nginx is by adding .conf files to /etc/nginx/main.d and /etc/nginx/conf.d
  • files in conf.d are included in the Nginx configuration's http context.
  • any environment variables you set with docker run -e, Docker linking and /etc/container_environment, won't reach Nginx.
  • To preserve these variables, place an Nginx config file ending with *.conf in the directory /etc/nginx/main.d, in which you tell Nginx to preserve these variables.
  • By default, Phusion Passenger sets all of the following environment variables to the value production
  • Setting these environment variables yourself (e.g. using docker run -e RAILS_ENV=...) will not have any effect, because Phusion Passenger overrides all of these environment variables.
  • PASSENGER_APP_ENV environment variable
  • passenger-docker autogenerates an Nginx configuration file (/etc/nginx/conf.d/00_app_env.conf) during container boot.
  • The configuration file is in /etc/redis/redis.conf. Modify it as you see fit, but make sure daemonize no is set.
  • You can add additional daemons to the image by creating runit entries.
  • The shell script must be called run, must be executable
  • the shell script must run the daemon without letting it daemonize/fork it.
  • We use RVM to install and to manage Ruby interpreters.
crazylion lee

darktable | the photo workflow software - 0 views

www.darktable.org

photography opensource software linux photos

shared by crazylion lee on 20 Nov 16 - No Cached
  • crazylion lee on 20 Nov 16
     
    "darktable is an open source photography workflow application and raw developer. A virtual lighttable and darkroom for photographers. It manages your digital negatives in a database, lets you view them through a zoomable lighttable and enables you to develop raw images and enhance them. "
crazylion lee

Realtime Multi-Person 2D Pose Estimation using Part Affinity Fields - 0 views

www.gitxiv.com/...estimation-using-part-affinity

pose 2d programming computer Science

shared by crazylion lee on 30 Jan 17 - No Cached
  • crazylion lee on 30 Jan 17
     
    "We present a realtime approach for multi-person 2D pose estimation that predicts vector fields, which we refer to as Part Affinity Fields (PAFs), that directly expose the association between anatomical parts in an image. The architecture is designed to jointly learn part locations and their association, via two branches of the same sequential prediction process."
crazylion lee

Flood fill - Wikipedia - 0 views

en.wikipedia.org/Flood_fill

computer programming Science algorithm fill

shared by crazylion lee on 30 Jan 17 - Cached
  • crazylion lee on 30 Jan 17
     
    "Flood fill, also called seed fill, is an algorithm that determines the area connected to a given node in a multi-dimensional array. It is used in the "bucket" fill tool of paint programs to fill connected, similarly-colored areas with a different color, and in games such as Go and Minesweeper for determining which pieces are cleared. When applied on an image to fill a particular bounded area with color, it is also known as boundary fill."
crazylion lee

Dropzone.js - 0 views

www.dropzonejs.com

javascript upload jquery fileupload drag drop file

shared by crazylion lee on 01 Apr 16 - No Cached
  • crazylion lee on 01 Apr 16
     
    "DropzoneJS is an open source library that provides drag'n'drop file uploads with image previews."
crazylion lee

favico.js - Make use of your favicon - 1 views

lab.ejci.net/favico.js

favicon javascript

shared by crazylion lee on 02 Apr 16 - No Cached
  • crazylion lee on 02 Apr 16
     
    "Make use of your favicon with badges, images or videos"
crazylion lee

Packer - 0 views

www.packer.io

virtualbox virtualization vmware digitalocean cloud

shared by crazylion lee on 17 Jan 14 - No Cached
  • crazylion lee on 17 Jan 14
     
    Packer is a tool for creating identical machine images for multiple platforms from a single source configuration.
張 旭

Getting Started with Docker - Servers for Hackers - 0 views

serversforhackers.com/getting-started-with-docker

docker system virtualization

shared by 張 旭 on 30 Apr 15 - No Cached
  • Docker is an isolated portion of the host computer, sharing the host kernel (OS) and even its bin/libraries if appropriate.
  • the Docker Container contains the parts that make Ubuntu different from CoreOS.
  • A Docker container only stays alive as long as there is an active process being run in it.
  • ...10 more annotations...
  • Allocate a (pseudo) tty
  • Keep stdin open (so we can interact with it)
  • Docker allows us make changes to an image, commit those changes, and then push those changes out somehwere.
  • Docker tracks any changes we make to a container
  • The Dockerfile provides a set of instructions for Docker to run on a container.
  • what image (and tag in this case) to base this off of
  • run the given command (as user "root")
  • copy a file from the host machine into the container
  • expose a port to the host machine. You can expose multiple ports
  • run a command
crazylion lee

Writing a Bootloader | Blog of Osanda - 1 views

osandamalith.wordpress.com/...writing-a-bootloader

bootloader linux c

shared by crazylion lee on 06 Nov 15 - No Cached
  • crazylion lee on 06 Nov 15
     
    "A bootloader is a special program that is executed each time a bootable device is initialized by the computer during its power on or reset that will load the kernel image into the memory. This application is very close to hardware and to the architecture of the CPU. All x86 PCs boot in Real Mode. In this mode you have only 16-bit instructions. Our bootloader runs in Real Mode and our bootloader is a 16-bit program."
crazylion lee

Classifier by bhrigu123 - 0 views

bhrigu123.github.io/classifier

python file

shared by crazylion lee on 02 Mar 16 - No Cached
  • crazylion lee on 02 Mar 16
     
    "Organize files in your current directory, by classifying them into folders of music, pdfs, images, etc."
crazylion lee

netboot.xyz - 0 views

netboot.xyz

netboot ipxe network boot linux

shared by crazylion lee on 27 Feb 16 - No Cached
  • crazylion lee on 27 Feb 16
     
    "The DHCP bootloaders will automatically get a network address if you have DHCP on your network while the static bootloaders will prompt you for network information. SHA256 checksums are generated during each build of iPXE and are located here. You can also view the scripts that are embedded into the images here. "
張 旭

How services work | Docker Documentation - 0 views

docs.docker.com/...services

docker swarm cluster system

shared by 張 旭 on 07 Sep 18 - No Cached
  • a service is the image for a microservice within the context of some larger application.
  • When you create a service, you specify which container image to use and which commands to execute inside running containers.
  • an overlay network for the service to connect to other services in the swarm
  • ...13 more annotations...
  • In the swarm mode model, each task invokes exactly one container
  • A task is analogous to a “slot” where the scheduler places a container.
  • A task is the atomic unit of scheduling within a swarm.
  • A task is a one-directional mechanism. It progresses monotonically through a series of states: assigned, prepared, running, etc.
  • Docker swarm mode is a general purpose scheduler and orchestrator.
  • Hypothetically, you could implement other types of tasks such as virtual machine tasks or non-containerized process tasks.
  • If all nodes are paused or drained, and you create a service, it is pending until a node becomes available.
  • reserve a specific amount of memory for a service.
  • impose placement constraints on the service
  • As the administrator of a swarm, you declare the desired state of your swarm, and the manager works with the nodes in the swarm to create that state.
  • two types of service deployments, replicated and global.
  • A global service is a service that runs one task on every node.
  • Good candidates for global services are monitoring agents, an anti-virus scanners or other types of containers that you want to run on every node in the swarm.
張 旭

Practical persistent cloud storage for Docker in AWS using RexRay - pt 4 - 0 views

blog.vizuri.com/ocker-in-aws-using-rexray-pt-4

docker volume disk aws storage

shared by 張 旭 on 14 Sep 18 - No Cached
  • Docker volumes can then be created and managed via the plugin, as requests are passed by Docker, and then orchestrated by the local server.
  • volumes are usually protected from deletion via a reference count.
  • Using the plugin means that the reference count is kept at the node level, so the plugin is only aware of the containers on a single node.
  • ...3 more annotations...
  • The S3FS plugin as of version 0.9.2 cannot delete an S3 bucket unless the bucket is empty, and has never been used (just created) as a Docker volume.
  • Starting with Docker 1.13 a new plugin system was introduced in which the plugin runs inside of a container.
  • Even though the plugin is a container image, you cannot start it using either docker image pull or docker container run; you need to use the docker plugin set of sub‑commands.
  • 張 旭 on 14 Sep 18
     
    "Docker volumes can then be created and managed via the plugin, as requests are passed by Docker, and then orchestrated by the local server."
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.
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