49 lines
2.8 KiB
Markdown
49 lines
2.8 KiB
Markdown
# Key CI/CD/Jenkins Concepts and their Usage
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## Configuring and Executing Jobs in a Distributed Build
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1. Go to "Manage Jenkins" > "Manage Nodes". You should see a single `master` node.
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2. Configure the `master` node by setting the # of executor value to 0. That will take care of never using the `master` for job workload.
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3. Have other physical or virtual machines ready that can act as agent nodes. Log into the machine as `root` user and create a new user named `jenkins` with the commands `useradd -d /var/lib/jenkins jenkins` and `passwd jenkins`. From the `master` node, copy the contents of the `id_rsa.key` file to the clipboard. Paste the contents of the clipboard to the file `/var/lib/jenkins/.ssh/authorized_keys`.
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4. Add new nodes by clicking "New Nodes". Enter an appropriate name and select the option "Permanent Agent". Use the remote directory `/home/jenkins/jenkins_slave` and set the # of executors to 2. Enter the host and provide credentials by selecting "SSH Username with private key". To keep things easy select "Non verifying Verification Strategy".
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4. Trigger a build. You should see that the build is only executed on the agent and not the `master` node.
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5. Add at least one more agent.
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6. Trigger a build. You should see that the build can be executed on any of the agents.
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7. Configure one of the agents to only build jobs with a specific label e.g. `java`. Change the "Usage" field to "Only build jobs with label expressions matching this node".
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8. Configure the `gradle-initializr` job and assign the label `java`.
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9. Trigger a build of the `gradle-initializr` job. It is only executed by the dedicated agent.
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10. Trigger other jobs that do not have the label `java` assigned to them. They are waiting for an agent that can execute the build.
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<details><summary>Show Solution</summary>
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<p>
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Configure the `master` node.
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Add a new agent node.
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You will see that the `master` node isn't even listed anymore in the executor overview.
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Reconfigure the agent node to only build jobs with a specific label.
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Reconfigure the job to only use agents that can handle a specific label.
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A build of the job is now only handled by an agent with the assigned label.
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Other jobs sit in a queue waiting for an agent that can handle the execution criteria.
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</p>
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</details> |