CI/CD Automation with Jenkins, Git, Docker & Kubernetes

Lab 18 of 20 · CI/CD & Jenkins · 5 hands-on activities · bilingual (English + සිංහල)

පිටුව 18: Jenkins CI/CD Pipeline එකෙන් Git, Docker සහ Kubernetes එකට සම්බන්ධ කරමු

Continuous Integration & Continuous Delivery සම්පූර්ණ workflow එක, Jenkinsfile Declarative Pipeline, Automated Webhooks, සහ initialAdminPassword.

Architectural Foundation & Systems Diagram

DevOps achieves continuous velocity through the CI/CD Pipeline. Whenever a software engineer commits code to Git, the pipeline automates testing, compiling, building a Docker container, and deploying to Kubernetes.

• ☕ Jenkins Architecture — Jenkins runs as a Java application on port 8080. It features a Controller (schedules jobs, manages GUI) and distributed Executor Agents (run build containers).

• 📜 The Declarative Jenkinsfile — Pipeline as Code stored directly in the Git repository:
  pipeline { agent any; stages { stage('Test') { ... } stage('Docker Build') { ... } stage('K8s Deploy') { ... } } }

• ⚡ Git Webhook Automation — GitHub sends an instant HTTP POST webhook to Jenkins upon git push. The pipeline triggers immediately, verifying code health in under 2 minutes!

Step-by-step practical lab

Step 01: Verify CI/CD Jenkins Daemon Runtime State

සිංහලෙන් — Jenkins CI/CD Automation Server එකේ තත්ත්වය පරීක්ෂා කරමු.

Verify that the Jenkins continuous integration and delivery daemon is healthy, enabled, and listening on port 8080.

systemctl status jenkins

• status : Jenkins CI/CD controller එකේ සජීවී තත්ත්වය පෙන්වයි.

Expected output

● jenkins.service - Jenkins Continuous Integration Server
   Loaded: loaded (/usr/lib/systemd/system/jenkins.service; enabled)
   Active: active (running) since Wed 2026-09-16 08:00:00 UTC
 Main PID: 2840 (java)
    Tasks: 48 (limit: 9480)
   Memory: 780.2M

Step 02: Retrieve initialAdminPassword Unlock Key

සිංහලෙන් — Jenkins Setup Wizard එක unlock කිරීමට initialAdminPassword එක ලබාගනිමු.

Extract the 32-character hexadecimal key required to unlock the Jenkins administrative web GUI.

cat /var/lib/jenkins/secrets/initialAdminPassword

• cat : Jenkins ස්ථාපනයෙන් පසු හදන secret admin unlock token එක පෙන්වයි.

Expected output

4f8b91a20c3d4e5f67890123456789ab

Step 03: Test Jenkins Web Listener via Curl

සිංහලෙන් — Jenkins Web Port 8080 එකට Curl කරලා පරීක්ෂා කරමු.

Send an HTTP GET probe to verify Jenkins web UI listener is responsive.

curl -I http://localhost:8080

• -I : HTTP Headers පමණක් ලබාගෙන Server එකේ තත්ත්වය (HTTP 200 OK) පරීක්ෂා කරයි.

Expected output

HTTP/1.1 200 OK
X-Jenkins: 2.452.1
Server: Jetty(11.0.20)
Content-Type: text/html;charset=utf-8

Hands-on practice activities

Work through these yourself — tick them off as you go.

• Activity 86: Verify Jenkins Daemon Runtime State (Drill) — Confirm that systemd unit jenkins.service is active and running on the host.
• Activity 87: Retrieve initialAdminPassword Unlock Key (Drill) — Extract the 32-character hexadecimal key to unlock Jenkins Setup Wizard.
• Activity 88: Test Jenkins Web Listener via Curl (Drill) — Send an HTTP GET probe to verify Jenkins web UI listener is responsive.
• Activity 89: Declarative Jenkinsfile Syntax Audit (Checkpoint) — Review syntax: pipeline { agent any; stages { stage('Build') { steps { sh 'make' } } } }.
• Activity 90: Jenkins Default Port Quiz (Quiz) — What is the default TCP port number used by Jenkins for its web user interface? Answer: Port 8080.

Keep going: ← Lab 17 · Lab 19 → · Track your progress in the Self Guide