Ubuntu 26.04 LTS Server の初期設定を自動化する（cloud-init）

#cloud-config
hostname: sv2
manage_etc_hosts: true
timezone: Asia/Tokyo
users:
  - name: kazulog
    groups: [sudo]
    shell: /bin/bash
    sudo: "ALL=(ALL) NOPASSWD:ALL"
    lock_passwd: false
    ssh_authorized_keys:
      - ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAA... kazulog@client
chpasswd:
  expire: false
  users:
    - name: kazulog
      password: kazulog
      type: text
package_update: true
packages:
  - git
  - nginx
write_files:
  - path: /etc/motd
    content: |
      このサーバーは cloud-init で構成されています。
  - path: /var/www/html/index.html
    content: "<h1>provisioned by cloud-init</h1>\n"
runcmd:
  - [systemctl, restart, nginx]
  - [sh, -c, "echo provisioned at $(date -Is) >> /var/log/provision.log"]

sudo apt install -y cloud-image-utils

kazulog@sv1:~$ which cloud-localds qemu-system-x86_64
/usr/bin/cloud-localds
/usr/bin/qemu-system-x86_64

cloud-localds [ISO] [USER-DATA]

kazulog@sv1:~$ cat user-data.yaml | head -6
#cloud-config
hostname: web01
manage_etc_hosts: true
timezone: Asia/Tokyo
users:
  - name: kazulog
kazulog@sv1:~$ cloud-localds seed.iso user-data.yaml
kazulog@sv1:~$ ls -lh seed.iso
-rw-rw-r-- 1 kazulog kazulog 366K Sep 10 21:19 seed.iso

cloud-localds -N [NETWORK-CONFIG] [ISO] [USER-DATA]

kazulog@sv1:~$ cloud-localds -N network-config.yaml seed.iso user-data.yaml
kazulog@sv1:~$ sudo mkdir -p /mnt/seed && sudo mount -o loop,ro seed.iso /mnt/seed
kazulog@sv1:~$ ls -l /mnt/seed
total 0
-rw-rw-r-- 1 kazulog kazulog  33 Sep 10 21:20 meta-data
-rw-r--r-- 1 kazulog kazulog  48 Sep 10 21:20 network-config
-rw-r--r-- 1 kazulog kazulog 478 Sep 10 21:20 user-data
kazulog@sv1:~$ sudo umount /mnt/seed

wget https://cloud-images.ubuntu.com/releases/26.04/release/ubuntu-26.04-server-cloudimg-amd64.img

qemu-system-x86_64 -enable-kvm -m 1024 -smp 1 -nographic \
  -drive if=pflash,format=raw,readonly=on,file=/usr/share/OVMF/OVMF_CODE_4M.fd \
  -drive if=pflash,format=raw,file=OVMF_VARS.fd \
  -drive file=ubuntu-26.04-server-cloudimg-amd64.img,format=qcow2,if=virtio \
  -drive file=seed.iso,format=raw,if=virtio \
  -net nic -net user

Ubuntu 26.04 LTS web01 ttyS0

web01 login: [  444.354111] sh[1072]: Completed socket interaction for boot stage config
[  462.016133] cloud-init[943]: Cloud-init v. 26.1-0ubuntu3~26.04.1 running 'modules:final' at Thu, 10 Sep 2026 12:57:00 +0000. Up 461.65 seconds.

[  465.718178] cloud-init[943]: Cloud-init v. 26.1-0ubuntu3~26.04.1 finished at Thu, 10 Sep 2026 12:57:04 +0000. Datasource DataSourceNoCloud [seed=/dev/vdb].  Up 465.66 seconds

cloud-init status --long

kazulog@sv2:~$ cloud-init --version
/usr/bin/cloud-init 26.1-0ubuntu3~26.04.1
kazulog@sv2:~$ cloud-init status --long
status: done
extended_status: done
boot_status_code: enabled-by-generator
last_update: Thu, 01 Jan 1970 00:00:27 +0000
detail: DataSourceNoCloud [seed=/dev/sr0]
errors: []
recoverable_errors: {}
kazulog@sv2:~$

kazulog@sv2:~$ sudo passwd -S kazulog
kazulog P 2026-09-10 0 99999 7 -1

kazulog@sv2:~$ hostname
sv2
kazulog@sv2:~$ id kazulog
uid=1000(kazulog) gid=1000(kazulog) groups=1000(kazulog),27(sudo)
kazulog@sv2:~$ cat /etc/motd
このサーバーは cloud-init で構成されています。
kazulog@sv2:~$ curl -s localhost | head -2
<h1>provisioned by cloud-init</h1>
kazulog@sv2:~$ cat /var/log/provision.log
provisioned at 2026-09-10T19:37:39+09:00
provisioned at 2026-09-10T19:42:01+09:00
kazulog@sv2:~$ dpkg -l git nginx | grep '^ii'
ii  git            1:2.53.0-1ubuntu1  amd64        fast, scalable, distributed revision control system
ii  nginx          1.28.3-2ubuntu1.10 amd64        small, powerful, scalable web/proxy server
kazulog@sv2:~$ timedatectl | head -3
               Local time: Thu 2026-09-10 19:42:26 JST
           Universal time: Thu 2026-09-10 10:42:26 UTC
                 RTC time: Thu 2026-09-10 10:42:26
kazulog@sv2:~$ ls -l ~/.ssh/authorized_keys
-rw------- 1 kazulog kazulog 110 Sep 10 19:41 /home/kazulog/.ssh/authorized_keys

cloud-init query platform
cloud-init query subplatform

kazulog@sv2:~$ cloud-init query platform
nocloud
kazulog@sv2:~$ cloud-init query subplatform
config-disk (/dev/sr0)
kazulog@sv2:~$

kazulog@sv2:~$ sudo head -11 /var/lib/cloud/instance/user-data.txt
#cloud-config
hostname: sv2
manage_etc_hosts: true
timezone: Asia/Tokyo
users:
  - name: kazulog
    groups: [sudo]
    shell: /bin/bash
    sudo: "ALL=(ALL) NOPASSWD:ALL"
    lock_passwd: false
    ssh_authorized_keys:
kazulog@sv2:~$

sudo cloud-init analyze blame

kazulog@sv2:~$ sudo cloud-init analyze blame | head -10
-- Boot Record 01 --
     07.24200s (modules-final/config-package_update_upgrade_install)
     00.75900s (modules-config/config-apt_configure)
     00.23800s (init-local/search-NoCloud)
     00.15500s (modules-final/config-keys_to_console)
     00.13400s (init-network/config-set_passwords)
     00.11000s (modules-final/config-scripts_user)
     00.10500s (init-network/config-growpart)
     00.10200s (init-network/config-ssh)
     00.07300s (modules-final/config-ssh_authkey_fingerprints)
kazulog@sv2:~$

kazulog@sv2:~$ sudo ls -l /var/log/cloud-init.log /var/log/cloud-init-output.log
-rw-r----- 1 root   adm   4059 Sep 10 19:42 /var/log/cloud-init-output.log
-rw-r----- 1 syslog adm 109119 Sep 10 19:42 /var/log/cloud-init.log
kazulog@sv2:~$

sudo cloud-init schema --config-file [FILE]

kazulog@sv2:~$ sudo cloud-init schema --config-file /tmp/good.yaml
Valid schema /tmp/good.yaml
kazulog@sv2:~$ sudo cloud-init schema --config-file /tmp/bad.yaml
Invalid user-data /tmp/bad.yaml
Error: Cloud config schema errors: packages: 'git' is not of type 'array', runcmds: Additional properties are not allowed ('runcmds' was unexpected)

Error: Invalid schema: user-data
kazulog@sv2:~$

kazulog@sv2:~$ sudo cloud-init schema --system | tail -3
2. network-config at /var/lib/cloud/instances/ubuntu/network-config.json:
  Valid schema network-config

sudo cloud-init clean --logs
sudo reboot

kazulog@sv2:~$ sudo cloud-init clean --logs
kazulog@sv2:~$ ls /var/lib/cloud/
seed
kazulog@sv2:~$

kazulog@sv2:~$ uptime -p
up 0 minutes
kazulog@sv2:~$ cloud-init status
status: done
kazulog@sv2:~$ cat /var/log/provision.log
provisioned at 2026-09-10T19:37:39+09:00
provisioned at 2026-09-10T19:42:01+09:00
provisioned at 2026-09-10T19:43:35+09:00
kazulog@sv2:~$ cat /etc/motd
このサーバーは cloud-init で構成されています。

sudo touch /etc/cloud/cloud-init.disabled

kazulog@sv2:~$ sudo touch /etc/cloud/cloud-init.disabled
kazulog@sv2:~$ ls -l /etc/cloud/cloud-init.disabled
-rw-r--r-- 1 root root 0 Sep 10 19:44 /etc/cloud/cloud-init.disabled
kazulog@sv2:~$

kazulog@sv2:~$ cloud-init status --long
status: disabled
extended_status: disabled
boot_status_code: disabled-by-marker-file
detail: Cloud-init disabled by /etc/cloud/cloud-init.disabled
errors: []
recoverable_errors: {}
kazulog@sv2:~$