Kaniko: Jenkins Pipeline

Saksham

So there are many things I have been simultaneously trying to learn & one of those is to learn how you can configure a pipeline

Read more about Pipeline as Code (PaC)

Objectives

  1. Learn Jenkins deployment on Kubernetes
  2. Learn Jenkins Kubernetes Plugin
  3. Learn Jenkins Pipeline (Declarative)
  4. How to build and deploy images in Kubernetes cluster

All right, with so many monkeys on my back I had to do things the way I know it works for me.

k8s cluster setup

I have a local cluster v1.23.1

Jenkins Setup

I have already covered steps to deploy a Jenkins instance here. A detailed list of all entities in the namespace jenkins are below

root@master>k get pods,services,pv,pvc,sa,serviceaccount,rolebinding -n jenkins
NAME              READY   STATUS    RESTARTS      AGE
pod/myjenkins-0   2/2     Running   18 (8h ago)   9d

NAME                      TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
service/myjenkins         ClusterIP   10.103.226.229   <none>        8080/TCP    9d
service/myjenkins-agent   ClusterIP   10.105.132.66    <none>        50000/TCP   9d

NAME                                              CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM                                     STORAGECLASS   REASON   AGE
persistentvolume/dx-restmon-restmon--default-pv   1Gi        RWO            Retain           Bound      default/dx-restmon-restmon--default-pvc                           71d
persistentvolume/jenkins-pv                       8Gi        RWO            Retain           Bound      jenkins/myjenkins                                                 9d
persistentvolume/kafka-pv                         8Gi        RWO            Retain           Bound      default/data-my-release-zookeeper-0                               3h36m
persistentvolume/prometheus-alertmanager          2Gi        RWO            Retain           Released   default/prometheus-alertmanager                                   88d
persistentvolume/prometheus-server                8Gi        RWO            Retain           Released   default/prometheus-server                                         88d
persistentvolume/zookeper-pv                      8Gi        RWO            Retain           Bound      default/data-my-release-kafka-0                                   3h34m

NAME                              STATUS   VOLUME       CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/myjenkins   Bound    jenkins-pv   8Gi        RWO                           9d

NAME                       SECRETS   AGE
serviceaccount/default     1         9d
serviceaccount/myjenkins   1         9d

NAME                                                               ROLE                             AGE
rolebinding.rbac.authorization.k8s.io/jenkins-admin-binding        ClusterRole/admin                2d
rolebinding.rbac.authorization.k8s.io/myjenkins-schedule-agents    Role/myjenkins-schedule-agents   9d
rolebinding.rbac.authorization.k8s.io/myjenkins-watch-configmaps   Role/myjenkins-casc-reload       9d

Official documentation is very detailed

https://www.jenkins.io/doc/book/installing/kubernetes/

Plugin Kubernetes

Configuring Kubernetes plugin was easier than I thought in Jenkins.

Kubernetes Plugin

https://plugins.jenkins.io/kubernetes/
Plugin Kubernetes

Once plugin is installed time to configure the plugin & nodes

Click the configure clouds

Server URL

root@master>kubectl config view --minify | grep server
    server: https://10.80.241.78:6443

Supply the values of the cluster information set-up the credentials (I named them jenkins) and click test connection

In Jenkins create a Secret Text credentials and paste the decoded value of the ServiceAccount token.

kubectl get secret $(kubectl get sa myjenkins -n jenkins -o jsonpath={.secrets[0].name}) -n jenkins -o jsonpath={.data.token} | base64 --decode

You can also retrieve server cert by using the command below

kubectl get secret $(kubectl get sa myjenkins -n jenkins -o jsonpath={.secrets[0].name}) -n jenkins -o jsonpath={.data.'ca\.crt'} | base64 --decode

My source code is posted here (Git HUB)

Two out of 4 objectives are done, time to create a pipeline.

Please refer to the usage section of the plugin.

The Kubernetes plugin allocates Jenkins agents in Kubernetes pods.

Plugin Kubernetes

Points to remember

  • Within these pods allocated there is always one special container jnlp that is running the Jenkins agent. Other containers can run arbitrary processes of your choosing, and it is possible to run commands dynamically in any container in the agent pod.
  • We define pod templates to use the kubernetes based pipelines.
  • Pod templates defined using the user interface declare a label. (Look for examples here)
podTemplate {
    node(POD_LABEL) {
       // Steps...
    }
}

Blocks of Pipeline (Declarative)

  • agent
  • environment
  • stages
  • steps
  • post

AGENT

  • The agent section defines the worker or machine where the pipeline will be executed.
  • Can be defined at the top level inside the pipeline block or overridden at the stage level.

ENVIRONMENT

  • The environment section defines a set of environment variables needed in the pipeline steps.
  • The variables can be defined as sequences of key-value pairs.
  • Reference credential variables can also be defined by using method credentials(), which takes as a parameter the ID of the target credential (defined in jenkins)

STAGES

  • This section defines actions a high level.

STEPS

  • The steps section contains a series of steps to be executed in a given stage directive.

POST

  • Depending on the location it is defined the post section will run upon the completion of a pipeline or stage run.
  • It contains commands or scripts

The above idiom creates a pod template with a generated unique label (available as POD_LABEL) and runs commands inside it.

Pod templates are used to create agents. They can be either configured via the user interface, or in a pipeline, using the podTemplate step.

Official documentation

Example

podTemplate(yaml: '''
    apiVersion: v1
    kind: Pod
    spec:
      volumes:
      - name: kaniko-secret
        secret:
          secretName: regcred
          items:
          - key: .dockerconfigjson
            path: config.json
      containers:
      - name: golang
        image: golang:latest
        command:
        - cat
        tty: true
      - name: kaniko
        image: gcr.io/kaniko-project/executor:debug
        command:
        - cat
        tty: true
        volumeMounts:
          - name: kaniko-secret
            mountPath: /kaniko/.docker
        
        
''')

You can read more about pipelines here.

Run the pipeline

I am using VS Code for my code management and Jenkins Runner plugin, so it is just matter of executing the pipeline on the default job configured.

Run the pipeline on default

& in Jenkins

In the docker hub

If you are curious why not docker in docker? It is a bad option but is well explained here.

Others

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