Debian Jenkins如何配置多节点

Prerequisites
Before configuring multi-node Jenkins on Debian, ensure the following:

• All nodes (master and agents) have Debian OS installed and updated (sudo apt update && sudo apt upgrade).
• Java 11+ is installed on all nodes (sudo apt install openjdk-11-jdk).
• The master node has a stable internet connection to download Jenkins and plugins.
• Basic familiarity with Jenkins web interface and Linux command line.

Step 1: Install Jenkins on Master and Agent Nodes

1. Add Jenkins Repository: On both master and agent nodes, add the official Jenkins APT repository to ensure access to stable builds.

   wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -
   sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
   sudo apt update
   

2. Install Jenkins: Run sudo apt install jenkins on both nodes. This installs Jenkins and starts the service automatically.
3. Start/Enable Services: Verify Jenkins is running with sudo systemctl status jenkins (should show “active (running)”). Enable auto-start on boot: sudo systemctl enable jenkins.

Step 2: Configure Jenkins Master Node

1. Access Web Interface: Open a browser and navigate to http://<master-node-ip>:8080. Unlock Jenkins using the initial admin password found in /var/lib/jenkins/secrets/initialAdminPassword.
2. Install Essential Plugins: Go to Manage Jenkins > Manage Plugins. Install critical plugins:
   • SSH Build Agents (for secure agent communication).
   • Pipeline (if using Declarative/Scripted Pipelines).
   • Node and Label Parameter (for dynamic node selection).
3. Adjust Master Configuration: Edit /etc/default/jenkins to:
   • Set HTTP_PORT=8080 (or a custom port if needed).
   • Ensure JENKINS_HOME=/var/lib/jenkins (default location for jobs/workspaces).
     Restart Jenkins to apply changes: sudo systemctl restart jenkins.

Step 3: Add Agent Nodes to Master

1. Create Agent Node in Master:
   • Navigate to Manage Jenkins > Manage Nodes and Clouds > New Node.
   • Enter a Node Name (e.g., debian-agent-01).
   • Select Permanent Agent and click OK.
   • Configure node details:
     • Remote Root Directory: Set a unique directory for the agent (e.g., /home/jenkins/agent).
     • Labels: Add descriptive labels (e.g., linux, debian) to group similar agents.
     • Usage: Choose “Use this node as much as possible” (default) or restrict to specific jobs.
     • Launch Method: Select Launch agents via SSH (recommended for security).
2. Configure SSH Credentials:
   • In the “Launch agents via SSH” section, click Add under “Credentials”.
   • Choose SSH Username with private key, enter the username (e.g., jenkins) for the agent node, and paste the private key (generated in Step 4).
3. Save Node Configuration: Click Save to finalize the agent setup.

Step 4: Configure SSH Authentication (Master → Agent)

1. Generate SSH Key Pair on Master:
   • Log in to the master node and run ssh-keygen -t rsa -b 4096. Press Enter to accept defaults (no passphrase for automation).
   • The private key is stored in ~/.ssh/id_rsa, and the public key in ~/.ssh/id_rsa.pub.
2. Copy Public Key to Agent Node:
   • Use ssh-copy-id jenkins@<agent-node-ip> to copy the master’s public key to the agent’s ~/.ssh/authorized_keys file.
   • Enter the agent node’s password when prompted. This enables password-less SSH login from master to agent.
3. Test SSH Connection: Run ssh jenkins@<agent-node-ip>. You should log in without a password.

Step 5: Verify Agent Connection

1. Check Agent Status in Master: Go to Manage Jenkins > Manage Nodes and Clouds. The agent node (e.g., debian-agent-01) should appear with a Connected status.
2. Run a Test Job:
   • Create a new Freestyle job in Jenkins.
   • Under Restrict where this project can be run, enter the agent’s label (e.g., linux).
   • Add a build step (e.g., Execute shell with echo "Hello from agent").
   • Save and run the job. Check the console output to confirm it executed on the agent node.

Optional: Set Up Load Balancing for High Availability
To distribute traffic across multiple master nodes (for high availability):

1. Install HAProxy: On a separate Debian node (or one of the masters), run sudo apt install haproxy.
2. Configure HAProxy: Edit /etc/haproxy/haproxy.cfg to include:

   frontend jenkins
       bind *:8080
       default_backend jenkins_servers
   backend jenkins_servers
       balance roundrobin
       server jenkins1 <master1-ip>:8080 check
       server jenkins2 <master2-ip>:8080 check
   

3. Restart HAProxy: sudo systemctl restart haproxy.
4. Access Jenkins via HAProxy: Use the HAProxy node’s IP/hostname (e.g., http://<haproxy-ip>:8080) to access Jenkins. Requests will be load-balanced across the configured masters.

Troubleshooting Tips

• Agent Not Connecting: Verify SSH connectivity (ssh jenkins@<agent-ip>), firewall rules (allow port 22), and Jenkins credentials (correct private key).
• Job Not Running on Agent: Check node labels (ensure they match the job restriction), agent status (must be “Connected”), and job configuration (correct “Restrict where this project can be run” setting).
• Java Issues: Ensure all nodes use the same Java version (OpenJDK 11+ recommended).