Jenkins Kube.netes pod 没有指定container('name')时使用什么容器？

Question

I have installed Jenkins from here https://charts.jenkins.io , reading Kube.netes Plugin page https://plugins.jenkins.io/kube.netes/ you can define a Jenkinsfile as

podTemplate(yaml: '''
    apiVersion: v1
    kind: Pod
    spec:
      containers:
      - name: maven
        image: maven:3.8.1-jdk-8
        command:
        - sleep
        args:
        - 99d
      - name: golang
        image: golang:1.16.5
        command:
        - sleep
        args:
        - 99d
''') {
  node(POD_LABEL) {
    stage('Get a Maven project') {
      git 'https://github.com/jenkinsci/kubernetes-plugin.git'
      container('maven') {
        stage('Build a Maven project') {
          sh 'mvn -B -ntp clean install'
        }
      }
    }

    stage('Get a Golang project') {
      git url: 'https://github.com/hashicorp/terraform-provider-google.git', branch: 'main'
      container('golang') {
        stage('Build a Go project') {
          sh '''
            mkdir -p /go/src/github.com/hashicorp
            ln -s `pwd` /go/src/github.com/hashicorp/terraform
            cd /go/src/github.com/hashicorp/terraform && make
          '''
        }
      }
    }

  }
}

The question is, if you enclose instructions inside a container('name') the instruction will be run with that container. But, if you do not specify a container, it works. I suppose that a random container is chosen to run the sh command? For example:

    stage('example stage') {
          sh 'echo "hello world"'
    }

Thanks

Answer 1

With declarative pipelines you can declare the pod definition and use defaultContainer to set the default. The Jenkins Kube.netes plugin will also inject a jnlp container in all pod definitions that runs the Jenkins agent node, and that is the default container.

You can check on the console log of jobs using the K8s plugin what is the final pod definition that is requested and instantiated by the cluster.