Ubuntu をアップデート後、Jenkins が起動しなくなってしまった。

Jenkins 起動不全

$ systemctl status jenkins.service
● jenkins.service - LSB: Start Jenkins at boot time
   Loaded: loaded (/etc/init.d/jenkins; generated)
   Active: failed (Result: exit-code) since Sun 2020-11-15 14:20:39 UTC; 19s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 1591 ExecStart=/etc/init.d/jenkins start (code=exited, status=1/FAILURE)
Nov 15 14:20:39 ip-172-31-83-123 systemd[1]: Starting LSB: Start Jenkins at boot time...
Nov 15 14:20:39 ip-172-31-83-123 jenkins[1591]: Found an incorrect Java version
Nov 15 14:20:39 ip-172-31-83-123 jenkins[1591]: Java version found:
Nov 15 14:20:39 ip-172-31-83-123 jenkins[1591]: openjdk version "11.0.9.1" 2020-11-04
Nov 15 14:20:39 ip-172-31-83-123 jenkins[1591]: OpenJDK Runtime Environment (build 11.0.9.1+1-Ubuntu-0ubuntu1.18.04)
Nov 15 14:20:39 ip-172-31-83-123 jenkins[1591]: OpenJDK 64-Bit Server VM (build 11.0.9.1+1-Ubuntu-0ubuntu1.18.04, mixed mode, sharing)
Nov 15 14:20:39 ip-172-31-83-123 jenkins[1591]: Aborting
Nov 15 14:20:39 ip-172-31-83-123 systemd[1]: jenkins.service: Control process exited, code=exited status=1
Nov 15 14:20:39 ip-172-31-83-123 systemd[1]: jenkins.service: Failed with result 'exit-code'.
Nov 15 14:20:39 ip-172-31-83-123 systemd[1]: Failed to start LSB: Start Jenkins at boot time.

解消方法

/etc/init.d/jenkins を以下のように編集

【Before】

# Which Java versions can be used to run Jenkins
JAVA_ALLOWED_VERSIONS=( "18" "110" )

【After】

# Which Java versions can be used to run Jenkins
JAVA_ALLOWED_VERSIONS=( "18" "110" "11.09" )

Jenkins 再起動

$ sudo systemctl restart jenkins
Warning: The unit file, source configuration file or drop-ins of jenkins.service changed on disk. Run 'systemctl daemon-reload' to reload units.

原因

以下のコマンドで Ubuntu をアップデートした際、Java のバージョンが上がってしまった模様

$ sudo apt update
$ sudo apt dist-upgrade
$ sudo apt autoremove

参考記事

jenkins — 「サービス開始ジェンキン」を実行するとジェンキンが失敗する