Running Jenkins jobs using Kubernetes plugin run by DEFAULT on JNLP container instead of my container

Question

as documented here, by default, commands in Jenkins agents will run in the jnlp container.

And yes, when I run my jenkins pipeline using this code, it will run on my main container -

node('node-agent'){
  container('main'){
  sh "ls -la"
 }
}

I want my jobs to run on 'main' container by default.

Like if I write this pipeline ->

node('node-agent'){
  sh "ls -la"
}

It will run on main instead of JNLP!

My jenkins as a code configuration -

Jenkins:cluster: non-prod
  Jenkins:secrets:
    create: true
    secretsList:
      - name: jenkins-github-token-non-prod
        value: /us-west-2-non-prod/jenkins/secrets/github-token
      - name: jenkins-slack-token-non-prod
        value: /us-west-2-non-prod/jenkins/secrets/slack-token
  Jenkins:config:
    chart: jenkins
    namespace: default
    repo: https://charts.jenkins.io
    values:
      agent:
        enabled: true
        podTemplates:
          jenkins-slave-pod: |
            - name: jenkins-slave-pod
              label: jenkins-slave-pod
              containers:
                - name: main
                  image: '805787217936.dkr.ecr.us-west-2.amazonaws.com/aba-jenkins-slave:ecs-global-node_master_57'
                  command: "sleep"
                  args: "30d"
                  privileged: true
        master.JCasC.enabled: true
        master.JCasC.defaultConfig: true
        kubernetesConnectTimeout: 5
        kubernetesReadTimeout: 15
        maxRequestsPerHostStr: "32"
        namespace: default
        image: "805787217936.dkr.ecr.us-west-2.amazonaws.com/aba-jenkins-slave"
        tag: "ecs-global-node_master_57"
        workingDir: "/home/jenkins/agent"
        nodeUsageMode: "NORMAL"
        # name of the secret to be used for image pulling
        imagePullSecretName:
        componentName: "eks-global-slave"
        websocket: false
        privileged: false
        runAsUser:
        runAsGroup:
        resources:
          requests:
            cpu: "512m"
            memory: "512Mi"
          limits:
            cpu: "512m"
            memory: "512Mi"
        podRetention: "Never"
        volumes: [ ]
        workspaceVolume: { }
        envVars: [ ]
        # - name: PATH
        #   value: /usr/local/bin
        command:
        args: "${computer.jnlpmac} ${computer.name}"
        # Side container name
        sideContainerName: "jnlp"
        # Doesn't allocate pseudo TTY by default
        TTYEnabled: true
        # Max number of spawned agent
        containerCap: 10
        # Pod name
        podName: "jnlp"
        # Allows the Pod to remain active for reuse until the configured number of
        # minutes has passed since the last step was executed on it.
        idleMinutes: 0
        # Timeout in seconds for an agent to be online
        connectTimeout: 100
      serviceAccount:
        annotations: {}
      controller:
        numExecutors: 1
        additionalExistingSecrets: []
        JCasC:
          securityRealm: |
            local:
                  allowsSignup: false
                  users:
                    - id: "aba"
                      password: "aba"
#          securityRealm: |
#            saml:
#              binding: "urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect"
#              displayNameAttributeName: "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name"
#              groupsAttributeName: "http://schemas.xmlsoap.org/claims/Group"
#              idpMetadataConfiguration:
#                period: 0
#                url: "https://aba.onelogin.com/saml/metadata/34349e62-799f-4378-9d2a-03b870cbd965"
#              maximumAuthenticationLifetime: 86400
#              usernameCaseConversion: "none"
#          authorizationStrategy: |-
#            roleBased:
#              forceExistingJobs: true
          configScripts:
            credentials: |
              credentials:
                system:
                  domainCredentials:
                    - credentials:
                        - string:
                            scope: GLOBAL
                            id: slack-token
                            description: "Slack access token"
                            secret: "${jenkins-slack-token-non-prod-value}"
                        - usernamePassword:
                            id: "github-credentials"
                            password: "aba"
                            scope: GLOBAL
                            username: "aba"
            plugin-config: |
              jenkins:
                disabledAdministrativeMonitors:
                  - "hudson.model.UpdateCenter$CoreUpdateMonitor"
                  - "jenkins.diagnostics.ControllerExecutorsNoAgents"
              security:
                updateSiteWarningsConfiguration:
                  ignoredWarnings:
                    - "core-2_263"
                    - "SECURITY-2617-extended-choice-parameter"
                    - "SECURITY-2170"
                    - "SECURITY-2796"
                    - "SECURITY-2169"
                    - "SECURITY-2332"
                    - "SECURITY-2232"
                    - "SECURITY-1351"
                    - "SECURITY-1350"
                    - "SECURITY-2888"
              unclassified:
                slackNotifier:
                  teamDomain: "superops"
                  baseUrl: "https://superops.slack.com/services/hooks/jenkins-ci/"
                  tokenCredentialId: "slack-token"
                globalLibraries:
                  libraries:
                    - defaultVersion: "master"
                      allowVersionOverride: true
                      name: "aba-jenkins-library"
                      implicit: true
                      retriever:
                        modernSCM:
                          scm:
                            git:
                              credentialsId: "github-credentials"
                              id: "shared-library-creds"
                              remote: "https://github.com/aba-aba/aba-jenkins-library.git"
                              traits:
                                - "gitBranchDiscovery"
                                - "cleanBeforeCheckoutTrait"
                                - "ignoreOnPushNotificationTrait"
        additionalPlugins:
        - junit:1119.1121.vc43d0fc45561
        - prometheus:2.0.11
        - saml:4.352.vb_722786ea_79d
        - role-strategy:546.ve16648865996
        - blueocean-web:1.25.5
        - github-branch-source:1677.v731f745ea_0cf
        - git-changelog:3.23
        - scriptler:3.5
        - sshd:3.249.v2dc2ea_416e33
        - rich-text-publisher-plugin:1.4
        - matrix-project:785.v06b_7f47b_c631
        - build-failure-analyzer:2.3.0
        - testng-plugin:555.va0d5f66521e3
        - allure-jenkins-plugin:2.30.2
        - timestamper:1.18
        - ws-cleanup:0.42
        - build-timeout:1.21
        - slack:616.v03b_1e98d13dd
        - email-ext:2.91
        - docker-commons:1.19
        - docker-workflow:521.v1a_a_dd2073b_2e
        - rundeck:3.6.11
        - parameter-separator:1.3
        - extended-choice-parameter:346.vd87693c5a_86c
        - uno-choice:2.6.3
        adminPassword: ""
        ingress:
          enabled: true
          hostName: jenkins.non-prod.us-west-2.int.isappcloud.com
          ingressClassName: nginx-int
        installPlugins:
        - kubernetes:3883.v4d70a_a_a_df034
        - workflow-aggregator:590.v6a_d052e5a_a_b_5
        - git:5.0.0
        - configuration-as-code:1569.vb_72405b_80249
        jenkinsUrlProtocol: https
        prometheus:
          enabled: true
        resources:
          limits:
            cpu: "4"
            memory: 8Gi
          requests:
            cpu: "2"
            memory: 4Gi
        sidecars:
          configAutoReload:
            resources:
              requests:
                cpu: 128m
                memory: 256Mi
        statefulSetAnnotations:
          pulumi.com/patchForce: "true"
          Name: eks-non-prod-us-west-2-jenkins
          department: aba
          division: enterprise
          environment: non-prod
          owner: devops
          project: eks-non-prod-us-west-2-jenkins
          team: infra
        tag: 2.362-jdk11
    version: 4.1.13
  Jenkins:stackTags:
    Name: eks-non-prod-us-west-2-jenkins
    department: aba
    division: enterprise
    environment: non-prod
    owner: devops
    project: eks-non-prod-us-west-2-jenkins
    team: infra
  aws:region: us-west-2

Answer 1

I would say that more convenient way will be using declarative pipeline with defaultContainer directive. Then you can specify provide your executor definition as standard pod definition file (put this in app repo or shared libraries) call them by name. This is example from doc:

pipeline {
  agent {
    kubernetes {
      defaultContainer 'maven'
      yamlFile 'KubernetesPod.yaml'
    }
  }

  stages {
    stage('Run maven') {
      steps {
        sh 'mvn -version'
      }
    }
  }
}