How to add a static slave to Jenkins running in Kubernetes?

Question

I've installed a Kubernetes cluster and deployed Jenkins in it which dynamically starts slave machines using Kubernetes plugin for Jenkins.

Some builds require a specific build machine with GNU make and specific kernel packages and for that I have a dedicated static virtual machine.

How can I automatically add the static virtual machine to Jenkins as a permanent slave? so when a Jenkins pod goes down and another starts it would automatically connect to the static slave?

Answer 1

Since I'm using Jenkins official helm chart which contains JCasC plugin (Jenkins Configuration as Code), I was able to configure the static slave attachment using it including the creation of relevant credentials.

Here's the relevant section of the values.yaml file I use to install/upgrade the Jenkins helm chart:

JCasC:
    defaultConfig: true
    configScripts:
      credentials: |
        credentials:
          system:
            domainCredentials:
              - credentials:
                  - usernamePassword:
                      scope: GLOBAL
                      id: "CentOS_7.1_k4.14.11_ssh_password"
                      username: 'jenkins'
                      password: ${decodeBase64:BASE64ENCODEDPASSWD}
                      description: "Username/Password Credentials for CentOS_7.1_k4.14.11"
      permanent-nodes: |
        jenkins:
          nodes:
            - permanent:
                name: "CentOS 7.1 k4.14.11"
                remoteFS: "/home/jenkins"
                numExecutors: 2
                labelString: "CentOS_7.1_k4.14.11"
                mode: EXCLUSIVE
                retentionStrategy: "always"
                launcher:
                  SSH:
                    jvmOptions: "-Xms256m -Xmx1024m -XX:MaxPermSize=1024m"
                    credentialsId: "CentOS_7.1_k4.14.11_ssh_password"
                    host: "10.1.66.120"
                    port: 22
                    sshHostKeyVerificationStrategy:
                      manuallyTrustedKeyVerificationStrategy:
                        requireInitialManualTrust: false

Now whenever I re-deploy or upgrade Jenkins helm chart, it automatically configures these credentials and add the static slave.