自VPSにdocker環境を作るメモ

DEV

インストール

公式に従って CentOS 9 Stream の自VPSへインストール

docs.docker.com

  • Set up the repository
sudo yum install -y yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
  • Install Docker Engine, containerd, and Docker Compose
sudo yum install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

dockerグループが自動で作られる。dockerグループに所属するユーザーはまだいない。

  • Start Docker
sudo systemctl start docker
  • Verify that the Docker Engine installation is successful by running the hello-world image.
sudo docker run hello-world

こんな出力がなされればOK

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/

For more examples and ideas, visit:
https://docs.docker.com/get-started/

docs.docker.com

Manage Docker as a non-root user

  • Create the docker group

dockerグループがすでにあるかを確認

cat /etc/group | grep docker

さきの手順でdockerグループが作られていれば、以下のような1行が出力されるはず。987 の部分は環境によって異なる

docker:x:987:

出力されなければ、手動でdockerグループを作る

sudo groupadd docker
  • Add your user to the docker group
sudo usermod -aG docker lmtak

ここではdockerグループにユーザーlmtakを追加した

  • Log out and log back in so that your group membership is re-evaluated

ログアウト→ログインするか、su で自ユーザーにログインしてもよい

su - lmtak
  • Verify that you can run docker commands without sudo

sudoなしでdockerコマンドが実行できればOK

docker run hello-world

さきと同じ出力がなされるはず

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/

For more examples and ideas, visit:
https://docs.docker.com/get-started/

  • Configure Docker to start on boot with systemd

OS起動時に、docker.service と containerd.service がサービス自動起動させる

 sudo systemctl enable docker.service
 sudo systemctl enable containerd.service

イメージ

ls -laF /var/lib/docker

total 52
drwx--x--- 12 root root 4096 Feb 27 09:27 ./
drwxr-xr-x. 29 root root 4096 Aug 30 07:43 ../
drwx--x--x 4 root root 4096 Aug 30 07:43 buildkit/
drwx--x--- 5 root root 4096 Feb 27 09:31 containers/

  • rw------- 1 root root 36 Aug 30 07:43 engine-id

drwx------ 3 root root 4096 Aug 30 07:43 image/
drwxr-x--- 3 root root 4096 Aug 30 07:43 network/
drwx--x--- 10 root root 4096 Feb 27 09:31 overlay2/
drwx------ 4 root root 4096 Aug 30 07:43 plugins/
drwx------ 2 root root 4096 Feb 27 09:27 runtimes/
drwx------ 2 root root 4096 Aug 30 07:43 swarm/
drwx------ 2 root root 4096 Feb 27 09:27 tmp/
drwx-----x 2 root root 4096 Feb 27 09:27 volumes/

containers の中身

ls -laF /var/lib/docker/containers

total 20
drwx--x--- 5 root root 4096 Feb 27 09:31 ./
drwx--x--- 12 root root 4096 Feb 27 09:27 ../
drwx--x--- 4 root root 4096 Feb 27 09:31 44a7142a6f691dd8904d9b5e85f55d7d5b6bf118aca6fef7c5b66988c6d44242/
drwx--x--- 4 root root 4096 Feb 27 09:28 45518d82aeabfa2e6e14bd0233e0969316366c06b380a6a0344fcb9da2de9c25/
drwx--x--- 4 root root 4096 Feb 27 09:27 7ab49285e28f943ccf4316b8dec38b2e5245d1ab8d68971871d50ed781d83d01/

ハッシュだと分かりにくいがしかたない

ls -laF /var/lib/docker/containers/44a71...

total 44
drwx--x--- 4 root root 4096 Feb 27 09:31 ./
drwx--x--- 5 root root 4096 Feb 27 09:31 ../

  • rw-r----- 1 root root 2348 Feb 27 09:31 44a7142a6f691dd8904d9b5e85f55d7d5b6bf118aca6fef7c5b66988c6d44242-json.log

drwx------ 2 root root 4096 Feb 27 09:31 checkpoints/

  • rw------- 1 root root 2506 Feb 27 09:31 config.v2.json
  • rw------- 1 root root 1462 Feb 27 09:31 hostconfig.json
  • rw-r--r-- 1 root root 13 Feb 27 09:31 hostname
  • rw-r--r-- 1 root root 174 Feb 27 09:31 hosts

drwx--x--- 2 root root 4096 Feb 27 09:31 mounts/

  • rw-r--r-- 1 root root 99 Feb 27 09:31 resolv.conf
  • rw-r--r-- 1 root root 71 Feb 27 09:31 resolv.conf.hash
cat /var/lib/docker/containers/44a71.../44a71....json.log

{"log":"\n","stream":"stdout","time":"2024-02-27T00:31:50.423961874Z"}
{"log":"Hello from Docker!\n","stream":"stdout","time":"2024-02-27T00:31:50.424012277Z"}
{"log":"This message shows that your installation appears to be working correctly.\n","stream":"stdout","time":"2024-02-27T00:31:50.424015811Z"}
{"log":"\n","stream":"stdout","time":"2024-02-27T00:31:50.424018274Z"}
{"log":"To generate this message, Docker took the following steps:\n","stream":"stdout","time":"2024-02-27T00:31:50.424020338Z"}
{"log":" 1. The Docker client contacted the Docker daemon.\n","stream":"stdout","time":"2024-02-27T00:31:50.424022476Z"}
{"log":" 2. The Docker daemon pulled the \"hello-world\" image from the Docker Hub.\n","stream":"stdout","time":"2024-02-27T00:31:50.424025148Z"}
{"log":" (amd64)\n","stream":"stdout","time":"2024-02-27T00:31:50.424027409Z"}
{"log":" 3. The Docker daemon created a new container from that image which runs the\n","stream":"stdout","time":"2024-02-27T00:31:50.424029426Z"}
{"log":" executable that produces the output you are currently reading.\n","stream":"stdout","time":"2024-02-27T00:31:50.424031541Z"}
{"log":" 4. The Docker daemon streamed that output to the Docker client, which sent it\n","stream":"stdout","time":"2024-02-27T00:31:50.424033591Z"}
{"log":" to your terminal.\n","stream":"stdout","time":"2024-02-27T00:31:50.424035697Z"}
{"log":"\n","stream":"stdout","time":"2024-02-27T00:31:50.424037695Z"}
{"log":"To try something more ambitious, you can run an Ubuntu container with:\n","stream":"stdout","time":"2024-02-27T00:31:50.424039628Z"}
{"log":" $ docker run -it ubuntu bash\n","stream":"stdout","time":"2024-02-27T00:31:50.424041831Z"}
{"log":"\n","stream":"stdout","time":"2024-02-27T00:31:50.424043876Z"}
{"log":"Share images, automate workflows, and more with a free Docker ID:\n","stream":"stdout","time":"2024-02-27T00:31:50.42404584Z"}
{"log":" https://hub.docker.com/\n","stream":"stdout","time":"2024-02-27T00:31:50.424048005Z"}
{"log":"\n","stream":"stdout","time":"2024-02-27T00:31:50.424050021Z"}
{"log":"For more examples and ideas, visit:\n","stream":"stdout","time":"2024-02-27T00:31:50.424051941Z"}
{"log":" https://docs.docker.com/get-started/\n","stream":"stdout","time":"2024-02-27T00:31:50.424054006Z"}
{"log":"\n","stream":"stdout","time":"2024-02-27T00:31:50.424056099Z"}

hello-worldイメージを実行したときの画面出力と同じものだ。1行1JSONオブジェクトのログとして保存されている