Environment Preparation

Jenkins requires a Java Development Kit (JDK) and a build tool like Maven to function correctly. The following steps outline the installation of these dependencies on a Linux system.

Installing OpenJDK 11

Modern versions of Jenkins require Java 11 or later. It is recommended to set up a dedicated directory for the Java installation.

mkdir -p /usr/lib/jvm
cd /usr/lib/jvm
wget https://repo.huaweicloud.com/openjdk/11.0.1/openjdk-11.0.1_linux-x64_bin.tar.gz
tar -xzf openjdk-11.0.1_linux-x64_bin.tar.gz
mv jdk-11.0.1 java-11
rm openjdk-11.0.1_linux-x64_bin.tar.gz

Configure the system environment variables by creating a profile script.

cat <<EOF > /etc/profile.d/jdk.sh
export JAVA_HOME=/usr/lib/jvm/java-11
export PATH=\$PATH:\$JAVA_HOME/bin
EOF

source /etc/profile.d/jdk.sh
java -version

Installing Apache Maven

Install Maven using the package manager and configure the mirror repository for faster dependency resolution.

yum install -y maven

Edit the Maven settings file located at /etc/maven/settings.xml to include the Aliyun mirror within the <mirrors> section.

<mirror>
  <id>aliyun-maven</id>
  <mirrorOf>central</mirrorOf>
  <name>Aliyun Maven Mirror</name>
  <url>https://maven.aliyun.com/repository/public</url>
</mirror>

Jenkins Server Installation

Add the official Jenkins repository to the system's package manager list.

wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo --no-check-certificate
rpm --import https://pkg.jenkins.io/redhat/jenkins.io.key
yum install -y jenkins

Service Configuration

Rather than using a manual startup script, managing Jenkins via systemd is recommended for stability and automatic startup capabilities. Locate the jenkins.war file to verify its path.

find / -name "jenkins.war"
# Typically located at /usr/share/java/jenkins.war

Create a systemd service unit file at /etc/systemd/system/jenkins.service. This configuration utilizes the installed JDK 11 and sets a custom HTTP port.

[Unit]
Description=Jenkins Continuous Integration Server
After=network.target

[Service]
Type=simple
User=root
Environment="JENKINS_HOME=/var/lib/jenkins"
WorkingDirectory=/var/lib/jenkins
ExecStart=/usr/lib/jvm/java-11/bin/java -jar /usr/share/java/jenkins.war --httpPort=8091
Restart=always

[Install]
WantedBy=multi-user.target

Reload the systemd daemon, enable the service to start on boot, and start the service.

systemctl daemon-reload
systemctl enable jenkins
systemctl start jenkins

Verify the service status and access the web interface at http://<server-ip>:8091.

Troubleshooting Plugin Installation

During the initial setup, the plugin installation wizard may encounter SSL certificate validation errors (PKIX path building failed). To resolve this, manually install the skip-certificate-check plugin.

Navigate to the Jenkins plugins directory and download the plugin manually.

mkdir -p /root/.jenkins/plugins
cd /root/.jenkins/plugins
wget https://mirrors.tuna.tsinghua.edu.cn/jenkins/plugins/skip-certificate-check/latest/skip-certificate-check.hpi

Restart the Jenkins service to load the plugin. After the restart, allow a few minutes for the initialization process to complete before attempting to install other plugins such as Git.

systemctl restart jenkins