Docker
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Docker is a utility to pack, ship and run any application as a lightweight container.
Contents
Installation
Install the docker package or, for the i686 architecture, the docker-gitAUR package. Next start docker.service and verify operation:
# docker info
If you want to be able to run docker as a regular user, add yourself to the docker group:
# gpasswd -a user docker
Then re-login or to make your current user session aware of this new group, you can use:
$ newgrp docker
Configuration
Proxies
Proxy configuration is broken down into two. First is the host configuration of the Docker daemon, second is the configuration required for your container to see your proxy.
Daemon Proxy Configuration
Copy /usr/lib/systemd/system/docker.service to /etc/systemd/system/docker.service. Then edit /etc/systemd/system/docker.service, where http_proxy is your proxy server and -g <path> is your docker home. The path defaults to /var/lib/docker.
[Service] Environment="http_proxy=192.168.1.1:3128"
Container Configuration
The settings in the docker.service file will not translate into containers. To achieve this you must set ENV variables in your Dockerfile thus:
FROM base/archlinux ENV http_proxy="http://192.168.1.1:3128" ENV https_proxy="https://192.168.1.1:3128"
Docker provide detailed information on configuration via ENV within a Dockerfile.
Daemon Socket Configuration
The docker daemon listens to a Unix socket by default. To listen on a specified port instead, edit /etc/systemd/system/docker.socket, where ListenStream is the used port:
[Socket] ListenStream=0.0.0.0:2375
Docker 0.9.0 -- 1.2.x and LXC
Since version 0.9.0 Docker provides a new way to start containers without relying on a LXC library called libcontainer.
The lxc exec driver and the -lxc-conf option may also be removed in the near future, [1]
Hence, you will not be able to use lxc-attach with containers managed by Docker 0.9.0+ by default. It is required to make Docker daemon run with -e lxc as an argument.
You can create a file named lxc.conf under /etc/systemd/system/docker.service.d/ with the following contents:
[Service] ExecStart= ExecStart=/usr/bin/docker -d -e lxc
Images
Arch Linux
x86_64
The following command pulls x86_64 Images.
# docker pull base/archlinux
i686
The default Arch Linux image in Docker Registry is for x86_64 only. i686 image must be built manually.
Build Image
Instead, check docker base/archlinux registry and click the mkimage-arch.sh link to download mkimage-arch.sh and mkimage-arch-pacman.conf to the same directory as raw files. Next, make the script executable and run it:
$ chmod +x mkimage-arch.sh $ cp /etc/pacman.conf ./mkimage-arch-pacman.conf # or get a pacman.conf from somewhere else $ LC_ALL=C ./mkimage-arch.sh # LC_ALL=C because the script parses the console output # docker run -t -i --rm archlinux /bin/bash # try it
For slow network connections or CPU, the build timeout can be extended:
$ sed -i 's/timeout 60/timeout 120/' mkimage-arch.sh
Debian
Build Debian image with debootstrapAUR from the AUR:
# mkdir wheezy-chroot # debootstrap wheezy ./wheezy-chroot http://http.debian.net/debian/ # cd wheezy-chroot # tar cpf - . | docker import - debian # docker run -t -i --rm debian /bin/bash
ArchLinux image with snapshot repository
Archlinux on Docker can become problematic when multiple images are created and updated each having different package versions. To keep Docker containers with consistent package versions a Docker image with a snapshot repository is available. This allows installing new packages from the official repository as it was on the day that the snapshot was created.
$ docker pull pritunl/archlinux:latest $ docker run --rm -t -i pritunl/archlinux:latest /bin/bash
Useful tips
To grab the IP address of a running container:
$ docker inspect --format '{{ .NetworkSettings.IPAddress }}' <container-name OR id>
172.17.0.37
Troubleshooting
Docker info errors out
If running docker info gives an error that looks like this:
FATA[0000] Get http:///var/run/docker.sock/v1.17/info: read unix /var/run/docker.sock: connection reset by peer. Are you trying to connect to a TLS-enabled daemon without TLS?
then you might not have the bridge module loaded. You can check for it by running lsmod . If it isn't loaded, you can try to load it with modprobe or simply reboot (a reboot might be required if you have upgraded your kernel recently without rebooting and the bridge module was built for the more recent kernel.)
See this issue on GitHub for more information.