ChromeOSのLinuxにDockerをインストール（GPG鍵の問題を解決）

ChromebookにDockerを入れるにはいくつか方法があり、(A) aptを使ったもっともオフィシャルなやり方、(B) GitHubでとあるユーザがシェアしたやりかた、(C) 公式のConvenience Script のどちらを実行しても、GPG keyのエラーが問題になり、7EA0A9C3F273FCD8 のpublic keyの問題があり、sudo apt-get update の部分で失敗していた。これを解決したので、途中の過程などを共有する。

TLDR: Docker GPG鍵の問題を解決する

# キーリングディレクトリが存在しない場合は作成
sudo install -m 0755 -d /etc/apt/keyrings

# DockerのGPG鍵を取得
curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# キーリングファイルのパーミッションを適切に設定
sudo chmod a+r /etc/apt/keyrings/docker.gpg


echo \
  "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/debian \
  "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

このあとに sudo apt-get updateが成功すれば、あとは色々なやりかたでdockerをインストールできる。(A)にせよ(B)にせよ、以下のようにできる。

sudo apt-get install docker-ce docker-ce-cli containerd.io
sudo docker run hello-world

エラーメッセージのケーススタディ

最初のsudo apt-get updateのところでスタックするのはあまり良いことではない。

(A) aptを使った最もオフィシャルなやりかた

ykanta@penguin:~$ sudo ./docker_install.sh 
Hit:1 https://deb.debian.org/debian bookworm InRelease
Hit:2 https://deb.debian.org/debian bookworm-updates InRelease               
Hit:3 https://deb.debian.org/debian-security bookworm-security InRelease     
Get:4 https://download.docker.com/linux/debian bookworm InRelease [46.6 kB]  
Ign:5 https://storage.googleapis.com/cros-packages/140 bookworm InRelease    
Hit:6 https://packages.cloud.google.com/apt cloud-sdk InRelease     
Hit:7 https://packages.microsoft.com/repos/code stable InRelease
Hit:8 https://storage.googleapis.com/cros-packages/140 bookworm Release
Err:4 https://download.docker.com/linux/debian bookworm InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
Reading package lists... Done
W: GPG error: https://download.docker.com/linux/debian bookworm InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
E: The repository 'https://download.docker.com/linux/debian bookworm InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

(B) Githubのとあるユーザが共有していたやりかた

GPG errorが出るので、このやりかたは途中でやめた。

ykanta@penguin:~$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian \
   $(lsb_release -cs) \
   stable"
Repository: 'deb [arch=amd64] https://download.docker.com/linux/debian bookworm stable'
Description:
Archive for codename: bookworm components: stable
More info: https://download.docker.com/linux/debian
Adding repository.
Press [ENTER] to continue or Ctrl-c to cancel.
Adding deb entry to /etc/apt/sources.list.d/archive_uri-https_download_docker_com_linux_debian-bookworm.list
Adding disabled deb-src entry to /etc/apt/sources.list.d/archive_uri-https_download_docker_com_linux_debian-bookworm.list
Hit:1 https://deb.debian.org/debian bookworm InRelease
Get:2 https://deb.debian.org/debian bookworm-updates InRelease [55.4 kB]     
Get:3 https://deb.debian.org/debian-security bookworm-security InRelease [48.0 kB]
Get:4 https://download.docker.com/linux/debian bookworm InRelease [46.6 kB]  
Get:5 https://packages.microsoft.com/repos/code stable InRelease [3,590 B]   
Hit:6 https://packages.cloud.google.com/apt cloud-sdk InRelease              
Ign:7 https://storage.googleapis.com/cros-packages/140 bookworm InRelease    
Hit:8 https://storage.googleapis.com/cros-packages/140 bookworm Release
Err:4 https://download.docker.com/linux/debian bookworm InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
Get:9 https://packages.microsoft.com/repos/code stable/main arm64 Packages [20.3 kB]
Reading package lists... Done      
W: GPG error: https://download.docker.com/linux/debian bookworm InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
E: The repository 'https://download.docker.com/linux/debian bookworm InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

(C) Convenience Scriptを試してみる

ykanta@penguin:~$ sudo sh get-docker.sh
# Executing docker install script, commit: 21ac930799ead7539270df8a220d0505ed0e660f
+ sh -c apt-get -qq update >/dev/null
W: GPG error: https://download.docker.com/linux/debian bookworm InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7EA0A9C3F273FCD8
E: The repository 'https://download.docker.com/linux/debian bookworm InRelease' is not signed.