Jenkins を起動しようとすると "Job for jenkins.service failed because the control process exited with error code" と怒られる

事象

AWS で EC2 インスタンス（Amazon Linux 2）を作成して、Jenkins を起動しようとすると、"Job for jenkins.service failed because the control process exited with error code. See " と怒られる。

$ sudo systemctl start jenkins
Job for jenkins.service failed because the control process exited with error code. See "systemctl status jenkins.service" and "journalctl -xe" for details.

/var/log/messages を見ると "Starting Jenkins bash: /usr/bin/java: No such file or directory" とメッセージが出ている。

$ sudo less /var/log/messages 
Feb 16 23:24:07 ip-172-31-18-89 jenkins: Starting Jenkins bash: /usr/bin/java: No such file or directory
Feb 16 23:24:07 ip-172-31-18-89 jenkins: [FAILED]
Feb 16 23:24:07 ip-172-31-18-89 systemd: jenkins.service: control process exited, code=exited status=1
Feb 16 23:24:07 ip-172-31-18-89 systemd: Failed to start LSB: Jenkins Automation Server.
Feb 16 23:24:07 ip-172-31-18-89 systemd: Unit jenkins.service entered failed state.
Feb 16 23:24:07 ip-172-31-18-89 systemd: jenkins.service failed.
Feb 16 23:24:27 ip-172-31-18-89 systemd: Starting LSB: Jenkins Automation Server...
Feb 16 23:24:27 ip-172-31-18-89 jenkins: Starting Jenkins bash: /usr/bin/java: No such file or directory ★
Feb 16 23:24:27 ip-172-31-18-89 jenkins: [FAILED]
Feb 16 23:24:27 ip-172-31-18-89 systemd: jenkins.service: control process exited, code=exited status=1
Feb 16 23:24:27 ip-172-31-18-89 systemd: Failed to start LSB: Jenkins Automation Server.
Feb 16 23:24:27 ip-172-31-18-89 systemd: Unit jenkins.service entered failed state.
Feb 16 23:24:27 ip-172-31-18-89 systemd: jenkins.service failed.

解決策

OpenJDK 8 か 11 をインストールする。

$ sudo yum -y install java-1.8.0-openjdk-devel.x86_64

Jenkins を実行するためには Java 8 か 11 の JRE またま JDK が必要。

Prerequisites
For this tour, you will require:

A machine with:

256 MB of RAM, although more than 512MB is recommended

10 GB of drive space (for Jenkins and your Docker image)

The following software installed:

Java 8 or 11 (either a JRE or Java Development Kit (JDK) is fine) ★

Docker (navigate to Get Docker at the top of the website to access the Docker download that’s suitable for your platform)

Getting started with the Guided Tour