As you may know, Kubernetes is all the rage these days. Kubernetes. Its feature list is impressive and it is no wonder why it is the go-to system of orchestrating your containers.

Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications.

I wanted to share my pipeline for building and updating containers in a Kubernetes cluster. In fact it’s quite straightforward. The pipeline includes: building a Docker container image, pushing the image to a container registry and updating the container image used in a Pod.

My environment is based in IBM Bluemix, so some commands will not apply…

stage ("Publish to Kubernetes cluster") {
   environment {
      JENKINSBOT = credentials('credentials-ID')
   }

   when {
      branch "develop"
   }

   steps {
      script {
         STAGE_NAME = "Publish to Kubernetes cluster"

         // Login to Bluemix and the Bluemix Container Registry
         sh '''
            bx login ...
            bx cr login
         '''

         // Build the Docker container image and push to Bluemix Container Registry
         sh '''
            docker build -t registry.../myimage:0.0.$BUILD_NUMBER --build-arg NPM_TOKEN=${NPM_TOKEN} .
            docker push registry.../myimage:0.0.$BUILD_NUMBER
         '''

         // Check for image vulnerabilities - applies only if you have such a service...
         isVulnerable = sh(script: "bx cr images --format '{{if and (eq .Repository \"registry.../myimage\") (eq .Tag \"0.0.$BUILD_NUMBER\")}}{{eq .Vulnerable \"Vulnerable\"}}{{end}}'", returnStatus: true)

         if (isVulnerable=="true") {
            error "Image may be vulnerable! failing the job."
         }

         // Apply Kubernetes configuration and update the pods in the cluster
         sh '''
            export KUBECONFIG=/home/idanadar/.bluemix/plugins/container-service/clusters/certmgmt/kube-config.yml
            kubectl set image deployment myimage myimage=registry.../myimage:0.0.$BUILD_NUMBER --record
         '''

         // If reached here, it means success. Notify
         slackSend (
            color: '#199515',
            message: "$JOB_NAME: <$BUILD_URL|Build #$BUILD_NUMBER> Kubernetes pod update passed successfully."
         )
      }
   }
}

Notes:
* I use $BUILD_NUMBER as the means to tag the image.
* I use a pre-defined export... to configure the session with the required configuration for the kubectl CLI to know which cluster to work with.
* The Bluemix Container Registry provides image scanning for vulnerabilities!
* I use kubectl set image ... to update the image used in the Pod(s). Works great with the replica setting.

More on Kubernetes in a later blog post.