普通に$ sudo apt install dockerしても動かなかったので調べてみたら、ラズパイでインストールするには"便利スクリプト"を使えとの事。

• Install Docker Engine on Debian
• Install using the convenience script

これを試してみる。OSバージョンなどは以下の通り。

$ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description:    Raspbian GNU/Linux 10 (buster)
Release:        10
Codename:       buster
$ cat /etc/debian_version
10.13
$ cat /etc/issue
Raspbian GNU/Linux 10 \n \l

$ uname -a
Linux raspberrypi 5.15.79-v7l+ #1600 SMP Fri Nov 18 18:23:26 GMT 2022 armv7l GNU/Linux

スクリプトをダウンロードして実行するだけ。

$ curl -fsSL https://get.docker.com -o get-docker.sh
$ DRY_RUN=1 sudo sh ./get-docker.sh
# Executing docker install script, commit: 4f282167c425347a931ccfd95cc91fab041d414f
+ sh -c apt-get update -qq >/dev/null
+ sh -c DEBIAN_FRONTEND=noninteractive apt-get install -y -qq apt-transport-https ca-certificates curl >/dev/null
+ sh -c mkdir -p /etc/apt/keyrings && chmod -R 0755 /etc/apt/keyrings
+ sh -c curl -fsSL "https://download.docker.com/linux/raspbian/gpg" | gpg --dearmor --yes -o /etc/apt/keyrings/docker.gpg
+ sh -c chmod a+r /etc/apt/keyrings/docker.gpg
+ sh -c echo "deb [arch=armhf signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/raspbian buster stable" > /etc/apt/sources.list.d/docker.list
+ sh -c apt-get update -qq >/dev/null
+ sh -c DEBIAN_FRONTEND=noninteractive apt-get install -y -qq --no-install-recommends docker-ce docker-ce-cli containerd.io docker-compose-plugin >/dev/null
+ version_gte 20.10
+ [ -z  ]
+ return 0
+ sh -c DEBIAN_FRONTEND=noninteractive apt-get install -y -qq docker-ce-rootless-extras >/dev/null
+ sh -c docker version
Client: Docker Engine - Community
 Version:           20.10.21
 API version:       1.41
 Go version:        go1.18.7
 Git commit:        baeda1f
 Built:             Tue Oct 25 17:59:34 2022
 OS/Arch:           linux/arm
 Context:           default
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          20.10.21
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.18.7
  Git commit:       3056208
  Built:            Tue Oct 25 17:57:24 2022
  OS/Arch:          linux/arm
  Experimental:     false
 containerd:
  Version:          1.6.10
  GitCommit:        770bd0108c32f3fb5c73ae1264f7e503fe7b2661
 runc:
  Version:          1.1.4
  GitCommit:        v1.1.4-0-g5fd4c4d
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

================================================================================

To run Docker as a non-privileged user, consider setting up the
Docker daemon in rootless mode for your user:

    dockerd-rootless-setuptool.sh install

Visit https://docs.docker.com/go/rootless/ to learn about rootless mode.


To run the Docker daemon as a fully privileged service, but granting non-root
users access, refer to https://docs.docker.com/go/daemon-access/

WARNING: Access to the remote API on a privileged Docker daemon is equivalent
         to root access on the host. Refer to the 'Docker daemon attack surface'
         documentation for details: https://docs.docker.com/go/attack-surface/

================================================================================
$ docker -v
Docker version 20.10.21, build baeda1f
$ docker compose version
Docker Compose version v2.12.2

公式ドキュメントではdry-runになる筈なのに、実際にインストールされてしまったようだ。 しかし試した限りではimageのpull、containerのrunはできたので良しとする。

アンインストール

試していないが、公式ドキュメントの記述が変わってしまう場合に備えてコピペしておく。

1. Uninstall the Docker Engine, CLI, containerd, and Docker Compose packages:

$ sudo apt-get purge docker-ce docker-ce-cli containerd.io docker-compose-plugin docker-ce-rootless-extras

2. Images, containers, volumes, or custom configuration files on your host aren’t automatically removed. To delete all images, containers, and volumes:

$ sudo rm -rf /var/lib/docker
$ sudo rm -rf /var/lib/containerd