Distributing a Jenkins Build

From the Jenkins Controller node, SSH into the Agent worker node and create the directory for the user's home:

[cloud_user@agent ]$ sudo mkdir /var/lib/jenkins

Add the user, assigning the home directory:

[cloud_user@agent ]$ sudo useradd -d /var/lib/jenkins jenkins

Make the user the owner of their home directory:

[cloud_user@agent ]$ sudo chown -R jenkins:jenkins /var/lib/jenkins

Create an .ssh directory for the jenkins user:

[cloud_user@agent ]$ sudo mkdir /var/lib/jenkins/.ssh

Run ssh-keygen. Hit Enter to accept defaults until it completes.

Copy the contents of ~/.ssh/id_rsa.pub to the file /var/lib/jenkins/.ssh/authorized_keys

[cloud_user@agent ]$ cat ~/.ssh/id_rsa.pub # Copy the output

[cloud_user@agent ]$ sudo vim /var/lib/jenkins/.ssh/authorized_keys # Paste the output of cat and save

We need the contents of id_rsa, as this is the private key that we will paste into Jenkins:

[cloud_user@agent ]$ cat ~/.ssh/id_rsa

Copy and save that command's output so we can use it later. After that, use exit to close out of the worker agent session to go back to the Jenkins controller session.

On the Jenkins controller, create an .ssh directory on the controller in the jenkins directory:

[cloud_user@jenkins ]$ sudo mkdir /var/lib/jenkins/.ssh

Copy the known_hosts entry over from the .ssh directory in /home/cloud_user to the jenkins user's .ssh directory:

[cloud_user@jenkins ]$ sudo cp ~/.ssh/known_hosts /var/lib/jenkins/.ssh

Log in to the Jenkins controller web interface using http://<PUBLIC_IP_OF_JENKINS_CONTROLLER>:8080. On the Jenkins controller, type:

• Username: student
• Password: OmgPassword!

On the Jenkins dashboard, go to Manage Jenkins and select Nodes.

On this page, click New Node, and then choose the Node name as worker1. Select Permanent Agent, and then click Create.

Fill out the following web form with these values:

• Number of Executors: Enter 2.
• Remote root directory: Enter /var/lib/jenkins.
• Labels: Enter linux.
• Launch method: Select Launch agents via SSH.
• Host: Enter the private IP of the worker agent.
• Credentials: Click Add, and enter Jenkins.
• Kind: Select SSH Username with private key.
• Description: Enter jssh.
• Username: Enter jenkins.
• Private Key: Enter it directly, and click Add.
• Paste in the RSA private key for the worker agent.
• Click Add.
• Choose the jenkins (jssh) option under Credentials.
• Leave any fields alone that weren't mentioned here, and click Save.

Give it a moment, and then click Refresh status to see that worker1 is in sync. If you have a problem, click worker1, and then click Log for more information.

We need to configure the master to use labels, to ensure default builds run on the remote.

Go back into the main Jenkins dashboard screen. In the left-hand menu, click Manage Jenkins.

Click System, and set the following values:

• On the Labels line, enter jenkins.
• Set Usage to Only build jobs with label expressions matching this node.
• Click Save.

Back out on the main Jenkins screen, click New Item. Enter an item name of test, click on Freestyle project, and then click OK.

On the next screen, scroll down to the Build Steps section, and choose Execute shell.

In the Command box, enter this:

hostname > location.txt

Now, in Post-build Actions, click the Add post-build action dropdown, and select Archive the artifacts. Paste location.txt in the Files to archive box. Click on Advanced, and check the box next to Fingerprint all archived artifacts.

Click Save.

Run the build by clicking Build Now in the left-hand menu, then click on the build number to get into the build itself. If we watch the Console Output, we'll see the build process happening.

Go back to the test environment (using the breadcrumb trail navigation at the top of the screen), and we will see location.txt listed in the Last Successful Artifacts section. Open the view link that's next to it in a new tab or window.