Jenkins Agent Node Configuration
Project Goal
The primary goal was to successfully connect three Linux Application Servers (stapp01, stapp02, stapp03) as permanent Jenkins agent nodes to the Jenkins controller using the SSH method.
Final Status
SUCCESS. All three agent nodes (App_server_1, App_server_2, and App_server_3) are now online, connected to the Jenkins controller, and ready to accept build jobs.
Prerequisite
| Step | Action |
|---|---|
| Install SSH Plugin | Navigate to Manage Jenkins then Manage Plugins then Available Plugins. Search for and install the "SSH Agents plugin" (or similar, depending on Jenkins version/naming). |
Core Jenkins UI Configuration (Per Node)
The following settings were applied when creating each new permanent node in Jenkins (Manage Jenkins then Manage Nodes then New Node).
1. Credentials Setup
Before configuring the node, the SSH credentials for each agent user were added to Jenkins.
- Navigate to Manage Jenkins then Credentials
- Click Add Credentials.
- Set Kind to
Username with private key(orSSH Username with password). - Input the Username (
tony,steve, orbanner). - Provide the corresponding Private Key (or Password).
- Assign an easily identifiable ID (e.g.,
tony-ssh-key). This ID is selected during node configuration.
2. Node Configuration Table
| Configuration Field | App_server_1 (stapp01) | App_server_2 (stapp02) | App_server_3 (stapp03) |
|---|---|---|---|
| Node Name | App_server_1 |
App_server_2 |
App_server_3 |
| Remote Root Directory | /home/tony/jenkins-agent |
/home/steve/jenkins-agent |
/home/banner/jenkins-agent |
| Labels | stapp01 |
stapp02 |
stapp03 |
| Launch Method | Launch agent via SSH |
Launch agent via SSH |
Launch agent via SSH |
| Host |
stapp01 (or its IP address) |
stapp02 (or its IP address) |
stapp03 (or its IP address) |
| Credentials | Select the tony credential ID |
Select the steve credential ID |
Select the banner credential ID |
| Host Key Verification Strategy |
Non-verifying Verification Strategy (or preferred method) |
Non-verifying Verification Strategy |
Non-verifying Verification Strategy |
| Usage | Only build jobs with label expressions matching this node |
Only build jobs with label expressions matching this node |
Only build jobs with label expressions matching this node |
Key Challenge Resolution: Java 21 Configuration Steps
The initial failure was due to the Jenkins SSH agent session failing to find the correct Java executable. The resolution involved guaranteeing that Java 21 was explicitly set up for the system and the agent users on all three App Servers.
Install Java 21:
sudo yum install java-21-openjdk -y
Final Step: Agent Launch
With all environment and Jenkins configurations complete, the nodes were successfully launched from the Jenkins UI, resolving the original dependency and credential errors, and transitioning all agents to an Online status.
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