Docker: Difference between revisions
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== Installation == | == Installation == | ||
The | The {{Pkg|docker}} package is in the ''community'' repository. See [[Repositories]] how to add a repository. | ||
apk add docker | apk add docker | ||
Connecting to the Docker daemon through its socket requires you to add yourself to the | Connecting to the Docker daemon through its socket requires you to add yourself to the <code>docker</code> group. | ||
addgroup | addgroup ${USER} docker | ||
To start the Docker daemon at boot, see [[ | To start the Docker daemon at boot, see [[OpenRC]]. | ||
rc-update add docker default | rc-update add docker default | ||
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=== Docker rootless === | === Docker rootless === | ||
Docker rootless allows unprivileged users to run the docker daemon and docker containers in user namespaces. | Docker rootless allows unprivileged users to run the docker daemon and docker containers in user namespaces. This is not the same as dockremap explained in the section below. With dockremap the daemon still runs as root. | ||
This requires the | This requires the {{Pkg|docker-rootless-extras}} package (available in ''community'') and enabling <code>cgroups v2</code>: | ||
edit <code>/etc/rc.conf</code> and set <code>rc_cgroup_mode="unified"</code>. Then start the service on boot: | |||
rc-update add cgroups | rc-update add cgroups | ||
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=== Docker Compose === | === Docker Compose === | ||
{{Pkg|docker-cli-compose}} is in the ''community'' repository starting with Alpine Linux 3.15. | |||
apk add docker-compose | apk add docker-cli-compose | ||
== Isolate containers with a user namespace == | == Isolate containers with a user namespace == | ||
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</pre> | </pre> | ||
add to | add to <code>/etc/docker/daemon.json</code> | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
''You may also consider these options : | ''You may also consider these options : '' | ||
"experimental": false, | "experimental": false, | ||
"live-restore": true, | "live-restore": true, | ||
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"no-new-privileges": false''''' | "no-new-privileges": false''''' | ||
You'll find all possible configurations | You'll find all possible configurations [https://docs.docker.com/engine/reference/commandline/dockerd/#daemon-configuration-file here]. | ||
== Example: How to install docker from Arch == | == Example: How to install docker from Arch == | ||
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==== Alpine 3.8 ==== | ==== Alpine 3.8 ==== | ||
It may not have been the case before, but with Alpine 3.8, you must | It may not have been the case before, but with Alpine 3.8, you must configure cgroups properly | ||
{{Warning|This seems ''not'' to work with Alpine 3.9 and Docker 18.06. Follow the instructions for grub or extlinux below instead.}} | |||
<pre>echo "cgroup /sys/fs/cgroup cgroup defaults 0 0" >> /etc/fstab</pre> | <pre>echo "cgroup /sys/fs/cgroup cgroup defaults 0 0" >> /etc/fstab</pre> | ||
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== How to use docker == | == How to use docker == | ||
Check the [https://docs.docker.com/ official documentation] for details on general usage of docker, including creating and management of containers. Repeating these instructions here be redundant. | |||
Public images can be browsed at the [https://hub.docker.com/ Docker Hub]. These should also serve as further reference on the Dockerfile format. | |||
Official Docker image files are denoted on the website by a | Official Docker image files are denoted on the website by a special badge. | ||
== See also == | == See also == | ||
Latest revision as of 23:44, 28 August 2024
Installation
The docker package is in the community repository. See Repositories how to add a repository.
apk add docker
Connecting to the Docker daemon through its socket requires you to add yourself to the docker group.
addgroup ${USER} docker
To start the Docker daemon at boot, see OpenRC.
rc-update add docker default service docker start
Docker rootless
Docker rootless allows unprivileged users to run the docker daemon and docker containers in user namespaces. This is not the same as dockremap explained in the section below. With dockremap the daemon still runs as root.
This requires the docker-rootless-extras package (available in community) and enabling cgroups v2:
edit /etc/rc.conf and set rc_cgroup_mode="unified". Then start the service on boot:
rc-update add cgroups
Additionally, the /etc/subuid and /etc/subgid files need to be set up as explained in the official documentation.
Docker Compose
docker-cli-compose is in the community repository starting with Alpine Linux 3.15.
apk add docker-cli-compose
Isolate containers with a user namespace
adduser -SDHs /sbin/nologin dockremap addgroup -S dockremap echo dockremap:$(cat /etc/passwd|grep dockremap|cut -d: -f3):65536 >> /etc/subuid echo dockremap:$(cat /etc/passwd|grep dockremap|cut -d: -f4):65536 >> /etc/subgid
add to /etc/docker/daemon.json
{
"userns-remap": "dockremap"
}
You may also consider these options :
"experimental": false,
"live-restore": true,
"ipv6": false,
"icc": false,
"no-new-privileges": false
You'll find all possible configurations here.
Example: How to install docker from Arch
https://wiki.archlinux.org/index.php/Docker
"WARNING: No {swap,memory} limit support"
You might encounter this message when executing docker info.
To correct this situation, we have to enable the cgroup_enable=memory swapaccount=1
Alpine 3.8
It may not have been the case before, but with Alpine 3.8, you must configure cgroups properly
echo "cgroup /sys/fs/cgroup cgroup defaults 0 0" >> /etc/fstab
cat >> /etc/cgconfig.conf <<EOF
mount {
cpuacct = /cgroup/cpuacct;
memory = /cgroup/memory;
devices = /cgroup/devices;
freezer = /cgroup/freezer;
net_cls = /cgroup/net_cls;
blkio = /cgroup/blkio;
cpuset = /cgroup/cpuset;
cpu = /cgroup/cpu;
}
EOF
Grub
If you use Grub, add the cgroup condition into /etc/default/grub, then upgrade your grub
GRUB_CMDLINE_LINUX_DEFAULT="... cgroup_enable=memory swapaccount=1"
Extlinux
With Extlinux, you add the cgroup condition, but inside of /etc/update-extlinux.conf
default_kernel_opts="... cgroup_enable=memory swapaccount=1"
then update the config and reboot
update-extlinux
How to use docker
Check the official documentation for details on general usage of docker, including creating and management of containers. Repeating these instructions here be redundant.
Public images can be browsed at the Docker Hub. These should also serve as further reference on the Dockerfile format.
Official Docker image files are denoted on the website by a special badge.