Pipeline node (Agent)¶

Agent describes the entire pipeline execution process or the execution environment of a certain stage , and must appear at the top of the description file or each stage .

This article describes how to extend the Jenkins Agent running in Kubernetes based on the Kubernetes plugin for Jenkins plugin.

Kubernetes Pod template introduction¶

This Kubernetes plugin will run a special container jnlp in the Jenkins Agent Pod. The purpose is to communicate between the Jenkins Controller and the Jenkins Agent, so you need to define other containers to run the pipeline steps, and you can use the container command to Switch between different containers.

Use the built-in Label¶

Workbench declares 6 labels through the podTemplate capability: base , maven , go , go16 , node.js and python . You can specify a specific Agent label to use the corresponding podTemplate.

• Can use go podTemplate via node('go') in Jenkinsfile.

  pipeline {
    agent {
      node {
        label 'go'
      }
    }
  
    stages {
      stage('go') {
        steps {
          container('go') {
            sh 'go version'
          }
        }
      }
    }
  }
  

• You can also select an Agent whose type is node and whose label is go on the Edit Pipeline page.

Built-in Labels¶

The built-in Jenkins Agent Labels have the following options:

Customize podTemplate using YAML¶

If you need to run the Jenkins Agent in a specific environment, you can customize the Jenkins Agent on the pipeline.

1. Select the Agent type as kubernetes on the Edit Pipeline page.

2. Click YAML Editor and fill in the YAML statement in the dialog box, refer to the following example:

   apiVersion: v1
   kind: Pod
   spec:
     containers:
     - name: jnlp
       image: docker.m.daocloud.io/jenkins/inbound-agent:4.10-2  # (1)!
       args:
       - ^${computer.jnlpmac} ^${computer.name}
     - name: golang
       image: golang:1.16.5   # (2)!
       command:
       - sleep
       args:
       - 99d
   

   1. You need to provide the address of the JNLP image, otherwise, the default "jenkins/inbound-agent" will be used.
   2. Fill in your custom image.

3. Enter golang in Container as the default container for pipeline operation.

4. To use other containers of the above examples in other steps of the pipeline, you can select Specify container to fill in the required container name.

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