Ubuntu 20 に Docker をインストールする

既に作成済みの Ubuntu 20 (ESXi 6.7u1 VM) を docker ホストとして，Docker 公式ページの手順に従ってインストールしていく

Ubuntu VM 確認

$ uname -a
Linux vm-ubuntu20-01 5.4.0-125-generic #141-Ubuntu SMP Wed Aug 10 13:42:03 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

既存パッケージの更新

$ sudo apt-get update
$ sudo apt-get upgrade

必要なパッケージの追加

$ sudo apt-get install ca-certificates curl gnupg lsb-release

Docker の公式 GPG キーを追加

$ sudo mkdir -p /etc/apt/keyrings
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

Docker リポジトリ情報の追加

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

リポジトリから Docker インストール

$ sudo apt-get update
$ sudo apt-get install docker-ce docker-ce-cli containerd.io docker-compose-plugin

インストール確認

$ sudo docker run hello-world

正常にインストールされたように見える．

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete
Digest: sha256:62af9efd515a25f84961b70f973a798d2eca956b1b2b026d0a4a63a3b0b6a3f2
Status: Downloaded newer image for hello-world:latest

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/

自動起動の確認

$ systemctl status docker
● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2022-09-17 08:21:07 UTC; 45min ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 953 (dockerd)
      Tasks: 9
     Memory: 95.4M
     CGroup: /system.slice/docker.service
             mq953 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

$ systemctl status containerd
● containerd.service - containerd container runtime
     Loaded: loaded (/lib/systemd/system/containerd.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2022-09-17 08:21:05 UTC; 52min ago
       Docs: https://containerd.io
    Process: 836 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
   Main PID: 875 (containerd)
      Tasks: 8
     Memory: 77.5M
     CGroup: /system.slice/containerd.service
             mq875 /usr/bin/containerd