Docker est un programme libre de création, gestion et déploiement de conteneurs. Vous pouvez trouver plus d'informations sur Wikipédia et sur de nombreux sites.

Un Raspberry Pi fonctionnel avec une distribution supportant Docker, comme Ubuntu Mate ou HypriotOS. Il faut que le noyau soit récent pour bénéficier de toutes les possibilités.

Sur Ubuntu Mate, on peut l'installer via les paquets :

$ sudo apt-get install docker.io

On peut vérifier qu'il est bien installé et trouver les infos importantes avec les commandes suivantes :

$ sudo docker 
Usage: docker [OPTIONS] COMMAND [arg...]
       docker daemon [ --help | ... ]
       docker [ --help | -v | --version ]
 
A self-sufficient runtime for containers.
 
Options:
 
  --config=~/.docker              Location of client config files
  -D, --debug                     Enable debug mode
  -H, --host=[]                   Daemon socket(s) to connect to
  -h, --help                      Print usage
  -l, --log-level=info            Set the logging level
  --tls                           Use TLS; implied by --tlsverify
  --tlscacert=~/.docker/ca.pem    Trust certs signed only by this CA
  --tlscert=~/.docker/cert.pem    Path to TLS certificate file
  --tlskey=~/.docker/key.pem      Path to TLS key file
  --tlsverify                     Use TLS and verify the remote
  -v, --version                   Print version information and quit
 
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 between a container and the local filesystem
    create    Create a new container
    diff      Inspect changes on a container's filesystem
    events    Get real time events from the server
    exec      Run a command in a running container
    export    Export a container's filesystem as a tar archive
    history   Show the history of an image
    images    List images
    import    Import the contents from a tarball to create a filesystem image
    info      Display system-wide information
    inspect   Return low-level information on a container or image
    kill      Kill a running container
    load      Load an image from a tar archive or STDIN
    login     Register or log in to a Docker registry
    logout    Log out from a Docker registry
    logs      Fetch the logs of a container
    network   Manage Docker networks
    pause     Pause all processes within a container
    port      List port mappings or a specific mapping for the CONTAINER
    ps        List containers
    pull      Pull an image or a repository from a registry
    push      Push an image or a repository to a registry
    rename    Rename a container
    restart   Restart a 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(s) to a tar archive
    search    Search the Docker Hub for images
    start     Start one or more stopped containers
    stats     Display a live stream of container(s) resource usage statistics
    stop      Stop a running container
    tag       Tag an image into a repository
    top       Display the running processes of a container
    unpause   Unpause all processes within a container
    update    Update resources of one or more containers
    version   Show the Docker version information
    volume    Manage Docker volumes
    wait      Block until a container stops, then print its exit code
 
Run 'docker COMMAND --help' for more information on a command.
 
$ sudo docker version
Client:
 Version:      1.10.3
 API version:  1.22
 Go version:   go1.6.1
 Git commit:   20f81dd
 Built:        Wed, 20 Apr 2016 14:19:16 -0700
 OS/Arch:      linux/arm
 
Server:
 Version:      1.10.3
 API version:  1.22
 Go version:   go1.6.1
 Git commit:   20f81dd
 Built:        Wed, 20 Apr 2016 14:19:16 -0700
 OS/Arch:      linux/arm
 
$ sudo docker info
[sudo] password for simon: 
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 1.10.3
Storage Driver: overlay
 Backing Filesystem: extfs
Execution Driver: native-0.2
Logging Driver: json-file
Plugins: 
 Volume: local
 Network: bridge null host
Kernel Version: 4.1.19-v7+
Operating System: Ubuntu 16.04.1 LTS
OSType: linux
Architecture: armv7l
CPUs: 4
Total Memory: 925.8 MiB
Name: rpi2
ID: K5PJ:JHJS:AEOJ:QMBV:N6GY:LEJY:L6GW:DJGT:7TCV:A247:62PI:O6H5
WARNING: No memory limit support
WARNING: No swap limit support
WARNING: No oom kill disable support
WARNING: No cpu cfs quota support
WARNING: No cpu cfs period support

Pour ne pas devoir utiliser sudo et pour limiter la surface d'attaque de Docker, on peut utiliser cette astuce :

# On ajoute le groupe docker s'il n'existe pas déjà.
$ sudo groupadd docker
 
# On ajoute l'utilisateur courant (nous) "${USER}" au groupe.
# On peut y mettre n'importe quel utilisateur
# Il faudra peut-être de reconnecter pour que les modifications prennent effet.
$ sudo gpasswd -a ${USER} docker
 
# On redémarre le daemon.
$ sudo service docker restart

1. Utiliser Docker sous Debian (Tuxunix.com)
2. Docker comme solution de virtualisation (guillaume-leduc.fr)
3. Virtualisation légère avec Docker (nicolargo.com)