!!! Docker

* [https://docs.docker.com]

Install with {{apt-get install docker.io}}. Beware that you need a 64bit version OS !

!! docker options

{{{
root@athena:~# docker
Usage: docker [OPTIONS] COMMAND [arg...]
 -H=[unix:///var/run/docker.sock]: tcp://host:port to bind/connect to or unix://path/to/socket to use

A self-sufficient runtime for linux containers.

Commands:
    attach    Attach to a running container
    build     Build an image from a Dockerfile
    commit    Create a new image from a container's changes
    cp        Copy files/folders from the containers filesystem to the host path
    diff      Inspect changes on a container's filesystem
    events    Get real time events from the server
    export    Stream the contents of a container as a tar archive
    history   Show the history of an image
    images    List images
    import    Create a new filesystem image from the contents of a tarball
    info      Display system-wide information
    inspect   Return low-level information on a container
    kill      Kill a running container
    load      Load an image from a tar archive
    login     Register or Login to the docker registry server
    logs      Fetch the logs of a container
    port      Lookup the public-facing port which is NAT-ed to PRIVATE_PORT
    pause     Pause all processes within a container
    ps        List containers
    pull      Pull an image or a repository from the docker registry server
    push      Push an image or a repository to the docker registry server
    restart   Restart a running container
    rm        Remove one or more containers
    rmi       Remove one or more images
    run       Run a command in a new container
    save      Save an image to a tar archive
    search    Search for an image in the docker index
    start     Start a stopped container
    stop      Stop a running container
    tag       Tag an image into a repository
    top       Lookup the running processes of a container
    unpause   Unpause a paused container
    version   Show the docker version information
    wait      Block until a container stops, then print its exit code

root@athena:~# 
}}}



Then simply start a container with : 
{{{docker run -i -t ubuntu /bin/bash}}}

This starts a container in interactive mode. The first time you run this, the image is downloaded from docker hub and stored locally. \\
When you exit the container, it is immediately "gone"  too.

With {{docker ps}} you can see what is running:
{{{
root@athena:~# docker ps
CONTAINER ID        IMAGE                 COMMAND             CREATED             STATUS              PORTS               NAMES
9539bc7b78df        ubuntu-14.04:latest   /bin/bash           6 seconds ago       Up 5 seconds                            silly_darwin    
}}}

Now, the funny thing is, you can do something in the container, like installing vim or openjdk-7-jdk, and then commit that (from outside the container) :
{{{
root@athena:~# docker commit -m "added java" -a "Harry Metske" e5acc9ff7c9c  ubuntu-14.04
feb996bac7c44edd0cfe28b54901f2ff500b4c18fed203931b703d14cc89b8c0
}}}

And after that you can see the results with {{docker images}} :
{{{
root@athena:~# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
ubuntu-14.04        latest              feb996bac7c4        12 seconds ago      664.2 MB
ubuntu/1404         v1.0                9e7a0bc71946        42 minutes ago      311.2 MB
ubuntu              latest              5506de2b643b        6 days ago          199.3 MB
}}}

After that you can run that new container again (and have java installed) :
{{{
 docker run -h hostje -i -t --user=metskem feb996bac7c4
}}}

* -h gives a hostname to the container (inside container)
* -i -t ==> interactive mode
* --user=metskem ==> start the shell with that user (that user must have been created earlier in the container)
* feb996bac7c4 ==> the unique id of the just committed image

You can also list the history of images:

{{{
root@athena:~# docker history feb996bac7c4
IMAGE               CREATED             CREATED BY                                      SIZE
feb996bac7c4        41 minutes ago      /bin/bash                                       353 MB
9e7a0bc71946        About an hour ago   /bin/bash                                       112 MB
5506de2b643b        6 days ago          /bin/sh -c #(nop) CMD [/bin/bash]               0 B
22093c35d77b        6 days ago          /bin/sh -c apt-get update && apt-get dist-upg   6.558 MB
3680052c0f5c        6 days ago          /bin/sh -c sed -i 's/^#\s*\(deb.*universe\)$/   1.895 kB
e791be0477f2        6 days ago          /bin/sh -c rm -rf /var/lib/apt/lists/*          0 B
ccb62158e970        6 days ago          /bin/sh -c echo '#!/bin/sh' > /usr/sbin/polic   194.8 kB
d497ad3926c8        9 days ago          /bin/sh -c #(nop) ADD file:3996e886f2aa934dda   192.5 MB
511136ea3c5a        16 months ago                                                       0 B
}}}

Note that no daemons are started after starting the container. For example, installing openssh-server (and update-rc.d defaults) it is not started after running the container ''==> find out, there must be other options''