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Docker on Alpine Linux

by Alejandro Liu
in 2018

tagged alpine, boot, installation, linux, service, ubuntu

Updated: 2022-01-04

Alpine Linux Quick installation

See wiki For Alpine Linux > 3.8

  1. Un-comment community repo from /etc/apk/repositories
  2. apk add docker
  3. rc-update add docker boot
  4. service docker start

Optional: (docker compose)

apk add docker-compose

Note 2021-03-21: When I tested this, the daemon.json did not work! Your mileage may vary.

Recommended for user namespace isolation (not sure if this works)

Also is good to use data mode (persistent /var) as most docker data is stored there.

adduser -SDHs /sbin/nologin dockremap
addgroup -S dockremap
echo dockremap:100000:65535 | tee /etc/subuid
echo dockremap:100000:65535 | tee /etc/subgid

In /etc/docker/daemon.json:

{
        "userns-remap": "dockremap"
}

For more info docker docs

Test docker:

  1. docker version
  2. docker info
  3. docker run hello-world
  4. docker image ls
  5. docker container ls
  6. docker container ls --all
  7. docker container ls --aq

Mounting NFS

From docker 17.06, you can mount NFS shares to the container directly when you run it, without the need of extra capabilities

docker run --mount 'type=volume,src=VOL_NAME,volume-driver=local,dst=/LOCAL-MNT,volume-opt=type=nfs,volume-opt=device=:/NFS-SHARE,"volume-opt=o=addr=NFS-SERVER,vers=4,hard,timeo=600,rsize=1048576,wsize=1048576,retrans=2"' -d -it --name mycontainer ubuntu

Useful options for docker

  • docker run -d : Run as a daemon (runs in the background).
  • NFS mounting (pre 17.06)
    • you@host > mount server:/dir /path/to/mount/point
    • you@host > docker run -v /path/to/mount/point:/path/to/mount/point
  • docker run -p 4000:80 : Forward port 4000 to 80. So host listens on port 4000 and everything is forwarded to port 80 on the container.

Alpine Linux relocating /var/lib/docker

In the file /etc/conf.d/docker you can add additional command line options in:

DOCKER_OPTS

In particular you can use the -g option.

See linuxconfig.org article

Make your own docker image, quick example

Making changes to an existing image

  • docker run -i -t [--name guest] image_name /bin/bash|/bin/sh
  • ... make changes to it ...
  • docker stop name|container_id
  • `docker commit -m 'change name' -a 'A N Other' container_id image_name
    • container id: $(docker ps -l -q)
  • docker rm guest|container_id

Better way to create container images:

Just use them...