Deploying web server using Jenkins-Groovy-code and Kubernetes

Jenkins is an open-source automation tool used to build and test your software projects continuously making it easier for developers to integrate changes to the project, and making it easier for users to obtain a fresh build.

But there is one task of making a job/pipeline which we do manually till now in all my tasks. So somehow, we say that this thing is not automated.

But Jenkins provides one way to make the job by writing code in Groovy language. For this, Jenkins has one plugin named Job_DSL. You need to install this only.

Now, you are ready to use Groovy code.

After this, go to create job and in Build, You find one option of Process Job DSL's, click on this.

You have both the option like if you want to give code directly, then choose Use the provided DSL script and give the code here. But If you want to run your code as a script, then choose Look on Filesystem and give the name of script with .groovy extension. Make sure you load your file on Jenkins workspace.

Now developers push the code in GitHub, and we need to create only one job for fetch the code from GitHub, this job is also known as Seed Job.

Task Overview:

1. Create container image that is has Jenkins installed using Dockerfile.

2. When we launch this image, it should automatically start Jenkins service in the container.

3. Create a job chain of job1, job2, job3 and job4 using build pipeline plugin in Jenkins 

4. Seed Job: Pull the GitHub repo automatically when some developers push the repo to GitHub.

5. Further on jobs should be pipeline using written code using Groovy language by the developer

6. Job1 :  

    1. By looking at the code or program file, Jenkins should automatically start the respective language interpreter installed image container to deploy code on top of Kubernetes ( e.g. If code is of PHP, then Jenkins should start the container that has PHP already installed )

    2. Expose your pod so that testing team could perform the testing on the pod

    3. Make the data to remain persistent using PVC (If server collects some data like logs, other user information )

7. Job2: Test your app if it is working or not.

8. Job3: if app is not working, then send email to the developer with error messages and redeploy the application after code is being edited by the developer

Tools used:

• Jenkins
• Kubernetes
• Docker
• Run Jenkins server using Docker image on the top of Kubernetes:

Dockerfile for creating image...

FROM centos

RUN sudo yum install wget -y

RUN sudo yum install git -y

RUN sudo yum install sudo -y

RUN sudo wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo

RUN sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key

RUN sudo yum install java-11-openjdk.x86_64 -y

RUN sudo yum install jenkins -y

RUN sudo yum install net-tools -y

RUN sudo yum install python36 -y

RUN sudo yum install /sbin/service -y

RUN sudo yum install initscripts -y

RUN sudo yum install httpd -y

RUN sudo yum install git -y

RUN sudo yum install vim -y

RUN sudo yum install openssh-clients -y

RUN echo -e "jenkins ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers

RUN sudo curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl

RUN sudo chmod +x ./kubectl

RUN sudo mv ./kubectl /usr/bin/

RUN sudo mkdir /kube_cert/

COPY  c* /kube_cert/

COPY  config /root/.kube/config

COPY yml /root/yml

RUN sudo yum install ncurses -y

CMD java -jar /usr/lib/jenkins/jenkins.war && /bin/bash

EXPOSE 8080

After creating the image, push the image into Docker Hub. Only thing you need to change is files of .kube folder.

You can use my image also by pull using command docker pull anuddeeph/Jenkins_k8s:v1

Now, this is the code for running Jenkins on top of Kubernetes using the YAML file.

apiVersion: v1

kind: Service

metadata:

  name: jenkins

  labels:

    app: jenkins

spec:

  ports:

    - port: 8080

  selector:

    app: jenkins

  type: NodePort

---

apiVersion: v1

kind: PersistentVolumeClaim

metadata:

  name: jenkins-claim

  labels:

    app: jenkins

spec:

  accessModes:

    - ReadWriteOnce

  resources:

    requests:

      storage: 10Gi

---

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2

kind: Deployment

metadata:

  name: jenkins

  labels:

    app: jenkins

spec:

  selector:

    matchLabels:

      app: jenkins

  strategy:

    type: Recreate

  template:

    metadata:

      labels:

        app: jenkins

    spec:

      containers:

      - image: anuddeeph/Jenkins_k8s:v1

        name: jenkins

        ports:

        - containerPort: 8080

          name: jenkins

        volumeMounts:

        - name: jenkins-storage

          mountPath: /root/.jenkins/

      volumes:

      - name: jenkins-storage

        persistentVolumeClaim:

          claimName: jenkins-claim

To run this, we are using the command...

kubectl apply -f file_name

Now Jenkins server is running...

First time when you run, this ask for password, for getting password, RUN kubectl logs pod_name

Now come to next step which is main part...

Jobs in Jenkins:

As I say, we need to create only one Seed job only, which create all the job automatically.

• Seed Job (Pull the GitHub repo when developer pushes some code):

Whenever the developer pushes any code in GitHub, this job automatically detects and copy in host OS and create other Jobs.

So, let us see what happens when we build this job...

First time, when you run it, it gives an error...

To remove this, go to Jenkins configuration -> In Process Script Approval and approve the script.

Now again build and this time output is...

You can see that two jobs and one view are created here.

And this is the pipeline view...

Push on RUN and your all jobs are running now...??

Job 2 is not running now; this conflict comes because I am not uploaded my mail password in GitHub. If you provided the right id/password, it works...??

After giving the required credentials,

Yo...This completed and now this is much automated than previous tasks...

Now let's see what I write in my groovy file(code.groovy)...

• Job1(Deploy deployment for website):

It launches the deployment with PVC and services. Here I have taken the example of webpages, so I have used the apache webserver.

job('job1-deploy-web-server') {

            description('This job is for deploy the web-server')

            steps {

                shell('sh /mycode/code.sh')

            }

        }

And code.sh is...

if kubectl get pods | grep httpd

        then

        echo "service is running"

        else

        kubectl create -f /mycode/http-pod.yaml

        sleep 20

        fi

        POD=$(kubectl get pod -l app=httpd -o jsonpath="{.items[0].metadata.name}")

        kubectl cp /mycode/*.html $POD:/var/www/html/

The YAML code is launching for the website is below...

apiVersion: v1

kind: Service

metadata:

  name: httpd

  labels:

    app: httpd

spec:

  ports:

    - nodePort: 80

      port: 80

      protocol: TCP

      targetPort: 80

  selector:

    app: httpd

  type: NodePort

---

apiVersion: v1

kind: PersistentVolumeClaim

metadata:

  name: httpd-claim

  labels:

    app: httpd

spec:

  accessModes:

    - ReadWriteOnce

  resources:

    requests:

      storage: 10Gi

---

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2

kind: Deployment

metadata:

  name: httpd

  labels:

    app: httpd

spec:

  selector:

    matchLabels:

      app: httpd

  strategy:

    type: Recreate

  template:

    metadata:

      labels:

        app: httpd

    spec:

      containers:

      - image: anuddeeph/apache-webserver-php

        name: httpd

        ports:

        - containerPort: 8080

          name: httpd

        volumeMounts:

        - name: httpd-storage

          mountPath: /var/www/html/

      volumes:

      - name: httpd-storage

        persistentVolumeClaim:

          claimName: httpd-claim

•    Job2(Testing that website is running or not) and Job3(Sent a mail to the developer):

After successfully build, Job1 will trigger Job2 and it checks the website that is working or not. If not working, it sent a notification to the developer.

Groovy code for this...

job('job2-test_code') {

            description('This job is for test the code and sent notification to developer')

            triggers {

                scm('@daily')

                upstream {

                    upstreamProjects('job1-deploy-web-server')

                    threshold('SUCCESS')

                }

            }

            steps {

                shell('sh /mycode/test_code.sh')

            }

        }

I write one script for do test here(test_code.sh)...

#!/bin/bash

        status=$(curl -o /dev/null -s -w "{%http_code}" https://192.168.99.101:32033)

        if [[ $status==200 ]]

        then

        python3 /mycode/mail.py

        else

        python3 /mycode/failed_mail.py

        fi

For creating a pipeline view, we use the below code...

 

buildPipelineView('Task 6') {

            filterBuildQueue()

            filterExecutors()

            title('Project for deploy web-server')

            displayedBuilds(5)

            selectedJob('job1-deploy-web-server')

            alwaysAllowManualTrigger()

            showPipelineParameters()

            refreshFrequency(60)

        }

Pull all the code in one file and your groovy script is ready??

GitHub Link... https://github.com/Anuddeeph/jenkins_dsl_code.git

Thanks for reading...??

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If have any query, please DM me...

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