100-Days-Of-DevOps-Challenge-KodeKloud

Jenkins Slave Nodes

The Nautilus DevOps team has installed and configured new Jenkins server in Stratos DC which they will use for CI/CD and for some automation tasks. There is a requirement to add all app servers as slave nodes in Jenkins so that they can perform tasks on these servers using Jenkins. Find below more details and accomplish the task accordingly.

Click on the Jenkins button on the top bar to access the Jenkins UI. Login using username admin and password Adm!n321.

1. Add all app servers as SSH build agent/slave nodes in Jenkins. Slave node name for app server 1, app server 2 and app server 3 must be App_server_1, App_server_2, App_server_3 respectively.

2. Add labels as below:

   • App_server_1 : stapp01
   • App_server_2 : stapp02
   • App_server_3 : stapp03
3. Remote root directory for
   • App_server_1 must be /home/tony/jenkins,
   • App_server_2 must be /home/steve/jenkins and
   • App_server_3 must be /home/banner/jenkins.
4. Make sure slave nodes are online and working properly.

Note:

1. You might need to install some plugins and restart Jenkins service. So, we recommend clicking on Restart Jenkins when installation is complete and no jobs are running on plugin installation/update page i.e update centre. Also, Jenkins UI sometimes gets stuck when Jenkins service restarts in the back end. In this case, please make sure to refresh the UI page.

2. For these kind of scenarios requiring changes to be done in a web UI, please take screenshots so that you can share it with us for review in case your task is marked incomplete. You may also consider using a screen recording software such as loom.com to record and share your work.

Steps

1. Update plugins and restart
2. Install the following plugins
   • SSH Build Agents
3. Add Credentials for three nodes
4. Add all three slave node following this way: Manage Jenkins > Credentials > System > Global Credentials > Add Credentials
   • username
   • password
   • ID

5. Login into each App Server and install java

   sudo yum install java-21-openjdk -y
   

6. Add Agent Nodes: Manage Jenkins > Nodes > Create an Agent Node:

   • label
   • Remote Directory
   • Launch Method: Launch Agent via SSH
     • Host
     • Credentials

7. Create a freestyle job: testNode:

   • Restrict where to run this job
   • select node label
   • Add execute shell as build step
   • paste these sample lines:

   echo "Hello from Agent"
   pwd
   echo $USER
   

8. Build job, it should be successfull

Good to Know?

Jenkins Distributed Builds

• Master-Slave Architecture: Master coordinates, slaves execute
• Scalability: Distribute build load across multiple machines
• Isolation: Separate build environments
• Resource Optimization: Use appropriate hardware for different tasks

Build Agents (Slaves)

• SSH Agents: Connect via SSH protocol
• JNLP Agents: Java Web Start agents
• Docker Agents: Containerized build environments
• Cloud Agents: Dynamic agents in cloud platforms

Agent Configuration

• Labels: Tag agents for specific job requirements
• Remote Directory: Workspace location on agent
• Executors: Number of concurrent builds per agent
• Node Properties: Environment variables and tools

Benefits

• Parallel Execution: Run multiple builds simultaneously
• Environment Diversity: Different OS, tools, configurations
• Load Distribution: Prevent master overload
• Fault Tolerance: Continue builds if some agents fail

Youtube Video

Watch the video tutorial here: https://youtu.be/KILDE85z8iw

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