Editing Docker

[[wikipedia:Docker_(software)|Docker]] is a software utility to pack, ship and run any [[container]]s application available since March [[2013]].

== Features ==
Docker offer the following features:
* Package an application and its dependencies in a virtual container that can run on any Linux server ([[docker images]])
* Pull or push [[docker images]] to a [[container repository]]/container registry (<code>[[docker pull]]</code><ref>https://docs.docker.com/engine/reference/commandline/pull/</ref>, <code>[[docker push]]</code>). By default docker hub but you can specify any other registry.

== Installing Docker ==
You can read official Docker documentation about installing Docker on your system: https://docs.docker.com/install/.

On macOS you can follow official documentation https://docs.docker.com/docker-for-mac/install/ which requires to create and account to download installer. You can also try:
<code>brew cask install docker</code> or try to follow https://pilsniak.com/how-to-install-docker-on-mac-os-using-brew/ instructions:
: <code>brew install docker [[docker-compose]] docker-machine</code>(to install docker and docker-compose)
: <code>brew cask install virtualbox</code>
: <code>docker-machine create --driver virtualbox default</code>
: <code>docker-machine ls</code>
: <code>docker-machine env default</code>
: <code>eval $(docker-machine env default)</code>
: <code>[[docker run]] hello-world</code> (will pull hello-world image and run it on docker)

On Ubuntu:
* <code>[[apt install docker.io]]</code>
*  <code>[[snap]] install docker</code> (officially provided by [[Canonical]])

=== Binaries ===
Following binaries will be installed: <code>[[docker-init]]</code>, <code>[[docker-proxy]]</code>, <code>docker</code> and <code>[[dockerd]]</code>

=== Verifying Docker installation ===
Once installed the Docker [[Daemon (computing)|daemon]], called <code>"dockerd"</code> should be running. 
You can also run <code>[[docker run]] hello-world</code> to verify docker correct installation.

=== Configuration files ===
Ubuntu:
* <code>/etc/docker/[[daemon.json]]</code> (Ref: https://docs.docker.com/engine/reference/commandline/dockerd/)
* <code>/etc/docker/[[key.json]]</code>

=== Directories ===
 [[/var/lib/]]docker (The Docker daemon was explicitly designed to have exclusive access to)<ref>https://jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/</ref>

== Docker Releases  ([[Docker Engine release notes]]) ==
* https://docs.docker.com/engine/release-notes/
* https://github.com/docker/docker-ce/releases
Use: <code>[[docker version]]</code><ref>https://docs.docker.com/engine/reference/commandline/version/</ref> to check your version.
You can download Docker CE source code from GitHub<ref>https://github.com/docker/docker-ce/releases</ref>.

= Docker Command Line =
You can read official docker command line documentation in https://docs.docker.com/engine/reference/commandline/docker/. Before being able to run docker commands you will have to install Docker on your machine.

Some typical task using containers:

== Docker verification commands ==
* Verify correct installation: <code>[[docker run]] hello-world</code>
You will see some message similar to this one:
<pre>
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
ca4f61b1923c: Pull complete
Digest: sha256:97ce6fa4b6cdc0790cda65fe7290b74cfebd9fa0c9b8c38e979330d547d22ce1
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://cloud.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/engine/userguide/
</pre>

== Docker image and container creation ==
* Create a new docker image base on ''alpine'' linux distribution and login into the new container: <code>[[docker run]] -it alpine sh</code>
* Create a new docker image: <code>[[docker build]]</code>
** Create a new docker image by creating a new text file with instructions, usually called <code>[[Dockerfile]]</code><ref>https://docs.docker.com/engine/reference/builder/</ref>: <code>docker build -f /path/to/a/Dockerfile .</code>
* Create a container: <code>[[docker create]]</code>
* Generate a mediawiki:1.27 image: <code>docker build --tag mediawiki:1.27  .</code> (you can use -t or --tag)
* Execute or run a container based on mediawiki:1.27 image: <code>docker run --name wikiFGA -p 0.0.0.0:9090:80 -d mediawiki:1.27</code>

== Docker Container Operation ==
* '''Start''' an existing container: <code>[[docker start]] CONTAINER_ID OR CONTAINER_NAME</code>. See also <code>[[docker run]]</code> and differences<ref>https://stackoverflow.com/questions/34782678/difference-between-running-and-starting-a-docker-container</ref> and <code>[[docker container start]]</code>
* '''Stop''' an running container: <code>docker stop container_id</code>

* '''Show''' only running containers:
** <code>[[docker container ls]]</code> <ref>https://docs.docker.com/engine/reference/commandline/container_ls/</ref> or <code>[[docker ps]]</code> <ref>https://docs.docker.com/engine/reference/commandline/ps/</ref>. (<code>[[docker container]] ls</code>) introduced in 2017 in [[Docker 1.13]]<ref>https://www.docker.com/blog/whats-new-in-docker-1-13/</ref> (There is no difference between both commands)<ref>https://stackoverflow.com/a/45254760</ref> 

* '''Show''' containers (running or not): 
** <code>[[docker ps]] -a </code>: https://docs.docker.com/engine/reference/commandline/ps/
** <code>docker container ls -a </code>. See also <code>[[docker-compose]] ps</code>

* '''Login/Connect''' into a running container:
** <code>[[docker exec]]<ref>https://docs.docker.com/engine/reference/commandline/exec/</ref> -it <my_container_name> bash</code>
** <code>docker exec -it <my_container_name> sh</code>
** <code> docker run -it --user USER_NAME CONTAINER_NAME</code>

*  '''Start''' stopped containers: <code>docker start $(docker ps -a -q -f status=exited)</code>
* '''Restart''' all containers: <code>docker restart $(docker ps -aq)</code> previously <code>docker restart $(docker ps -q)</code><code>-a all -q quiet</code><ref>https://stackoverflow.com/questions/38221463/command-for-restarting-all-running-docker-containers</ref>

* [[Start configuration behavior and restart policy]]<ref>https://docs.docker.com/config/containers/start-containers-automatically/#use-a-restart-policy</ref> 

* <code>[[docker container update]]</code>

* <code>[[docker kill]]</code>

See also: <code>[[docker compose]]</code> and <code>[[docker stack]]</code>

== [[Docker images management]] ==
{{docker images TOC}}

=== Docker Network command line commands ===
{{docker network TOC}}
* <code>docker network -rm</code>

=== Docker resource limitation ===
* Limit container '''CPU''' usage to 0.5 cpus: <code>[[docker run]] -it --cpus=".5" docker_image /bin/bash</code>
* Limit [[memory]] requires your kernel to have functionality activated, you can check it executing<code>[[docker info]]</code>. See https://docs.docker.com/install/linux/linux-postinstall/ and [[docker-compose]] resource limitation example: [[Version 3 resouces]]

=== Docker: Working with remote repositories/registries ===
You will be using mainly the following commands <code>[[docker login]]</code>, <code>docker logout</code>, <code>[[docker pull]]</code> and <code>docker push</code>. Docker registry allow to configure notifications. <ref>https://docs.docker.com/registry/notifications/</ref>. Docker has a public repository called Docker Hub and cloud providers offer repositories services such as AWS Elastic Container Registry (ECR).

=== Docker Information ===
* <code>[[docker version]]</code> https://docs.docker.com/engine/reference/commandline/version/
* <code>[[docker info]]</code> https://docs.docker.com/engine/reference/commandline/info/
* <code>[[docker stats]]</code> https://docs.docker.com/engine/reference/commandline/stats/
* <code>[[docker system info]]</code> https://docs.docker.com/v17.12/edge/engine/reference/commandline/system_info/
* <code>docker system events</code> https://docs.docker.com/v17.12/edge/engine/reference/commandline/system_events/
* <code>[[docker system df]]</code>
* <code>[[docker top]][CONTAINER_NAME or CONTAINER_ID]</code> https://docs.docker.com/engine/reference/commandline/top/
* <code>[[docker inspect]] CONTAINER_ID|IMAGE_ID</code><ref>http://manpages.ubuntu.com/manpages/disco/man1/docker-inspect.1.html</ref> https://docs.docker.com/engine/reference/commandline/inspect/ also available for: container, image, volume, network, node, service, or task
* <code>[[docker images]]</code>,  <code>[[docker images]] -q</code>
* <code>[[docker image inspect]]</code><ref>https://docs.docker.com/engine/reference/commandline/image_inspect/</ref>
* <code>[[docker image ls]]</code> or <code>[[docker image ls]] --no-trunc </code>
* <code>[[docker volume ls]]</code>
* <code>[[docker history]] IMAGE</code>
* <code>[[docker ps]]</code>

=== Docker Operation ===
* <code>[[docker run]]<ref>https://docs.docker.com/engine/reference/run/</ref> IMAGE|IMAGE_ID </code>: https://docs.docker.com/engine/reference/run/
* <code>[[docker start]] CONTAINER_ID|CONTAINER_NAME</code>: https://docs.docker.com/engine/reference/commandline/start/ 
* <code>[[docker stop]] CONTAINER_ID|CONTAINER_NAME</code>: https://docs.docker.com/engine/reference/commandline/stop/
* <code>[[docker restart]] CONTAINER_ID|CONTAINER_NAME</code>: https://docs.docker.com/engine/reference/commandline/restart/

=== Docker/[[cgroup]] Performance information ===
* <code>[[systemd-cgtop]]</code>

=== [[Docker Swarm]] ===
{{docker swarm TOC}}
* <code>[[docker service create]]</code>

=== Maintenance ===
* <code>[[docker system prune]] -a</code> remove unused and dangling images. Therefore any images being used in a container, whether they have been exited or currently running, will NOT be affected.<ref>https://stackoverflow.com/a/45143234</ref>. See also: <code>[[docker system info]]</code>

=== [[Docker Volumes]] ===
{{docker volumes}}

=== Secrets ===
* <code>[[docker secrets]]</code> (Feb 2017)<ref>https://www.docker.com/blog/docker-secrets-management/</ref> ([[swarm]] mode only)

== [[Docker logging]] ==

== Related terms==
* <code>[[DevOps/Docker/docker tag|docker tag]]</code><ref>https://docs.docker.com/engine/reference/commandline/tag/</ref>
* <code>[[docker registry]]</code>
* [[OverlayFS]]

== Activities ==
# Read docker blog: https://blog.docker.com/
# Read [[Docker Engine release notes]] (2017) and [[Docker CE]] or [[Docker EE]] releases.
# Understand the difference between an image and a container, Docker Images vs. Containers: https://stackoverflow.com/a/26960888
# Understand the difference between <code>[[docker start]]</code> and <code>[[docker run]]</code>: https://stackoverflow.com/questions/34782678/difference-between-running-and-starting-a-docker-container. See also [[runC]]
# Read Stackoverflow questions related to docker: https://stackoverflow.com/questions/tagged/docker?tab=Votes
# Read about Docker Image Manifest Version 2, Schema 2: https://github.com/docker/distribution/blob/fda42e5ef908bdba722d435ff1f330d40dfcd56c/docs/spec/manifest-v2-2.md

== See also ==
* {{Docker}}
* {{Dockerd}}
* [[wikipedia:Docker (software)| Docker Hub]] official Docker container image [[registry]]
* {{docker-compose}}
* [[Elastic Container Service]] ([[ECS]])
* AWS Elastic Container Registry ([[ECR]])
* {{K8s}}
* {{K8s cloud services}}
* {{container orchestration}}
* {{Virtualization}}



{{CC license}}
Source: https://en.wikiversity.org/wiki/DevOps/Docker


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[[Category:Software development]]
[[Category:Server administration]]
[[Category:Docker]]
[[Category:Linux containers]]