👷

A Full CI/CD Pipeline

Build, containerise, push, and deploy — with a human gate before production.

⏱11 min read📚DevOps Fundamentals

Time to connect everything you’ve learned into one real pipeline. We’ll take code, test it, package it as a Docker image, push it to a registry, and deploy it — with an approval step before production. This is a genuine end-to-end CI/CD flow.

🎯 Learning Objectives

By the end of this lesson you will:

Build and tag a Docker image inside a pipeline
Push the image to a registry using credentials
Add a manual approval gate before production
Structure a complete CI/CD Jenkinsfile

The Pipeline Stages

A production CI/CD pipeline usually flows like this:

text

Checkout → Test → Build Image → Push Image → Deploy Staging → [Approve] → Deploy Prod

Each stage builds on the last, and the approval gate ensures a human confirms before the highest-risk step.

Building and Pushing a Docker Image

Using an image tagged with the build number gives every build a unique, traceable artifact:

groovy

stage('Build Image') {
steps {
  sh 'docker build -t myapp:${BUILD_NUMBER} .'
}
}
stage('Push Image') {
steps {
  withCredentials([usernamePassword(
    credentialsId: 'dockerhub',
    usernameVariable: 'USER',
    passwordVariable: 'PASS')]) {
    sh '''
      echo "$PASS" | docker login -u "$USER" --password-stdin
      docker push myapp:${BUILD_NUMBER}
    '''
  }
}
}

💡 Tag with the build number

myapp:${BUILD_NUMBER} gives each build a unique tag, so you always know exactly which image is running and can roll back to a specific one. Avoid deploying latest to production — it’s ambiguous.

The Approval Gate

The input step pauses the pipeline and waits for a human to approve — perfect before a production deploy:

groovy

stage('Approve Production') {
steps {
  input message: 'Deploy to production?', ok: 'Deploy'
}
}
stage('Deploy Production') {
steps {
  sh './deploy.sh production myapp:${BUILD_NUMBER}'
}
}

bash — 80×24

student@devops:~$# Stage View, paused at the gate:

Checkout        ✓
Test            ✓
Build Image     ✓
Push Image      ✓
Deploy Staging  ✓
Approve Prod    ⏸  Waiting: 'Deploy to production?'  [Deploy] [Abort]

⚠ Guard the input step

By default anyone with access can approve an input. Use the submitter parameter to restrict approval to specific users or groups, so only authorised people can release to production.

Putting It All Together

The complete Jenkinsfile:

groovy

pipeline {
agent any
environment { IMAGE = "myapp:${BUILD_NUMBER}" }

stages {
  stage('Checkout') { steps { checkout scm } }
  stage('Test')     { steps { sh 'npm ci && npm test' } }
  stage('Build Image') { steps { sh 'docker build -t $IMAGE .' } }
  stage('Push Image') {
    steps {
      withCredentials([usernamePassword(credentialsId: 'dockerhub',
        usernameVariable: 'USER', passwordVariable: 'PASS')]) {
        sh 'echo "$PASS" | docker login -u "$USER" --password-stdin && docker push $IMAGE'
      }
    }
  }
  stage('Deploy Staging') { steps { sh './deploy.sh staging $IMAGE' } }
  stage('Approve') { steps { input message: 'Deploy to production?', ok: 'Deploy' } }
  stage('Deploy Production') { steps { sh './deploy.sh production $IMAGE' } }
}

post {
  failure { echo 'Build failed — notify the team' }
  always  { sh 'docker logout || true' }
}
}

🧪 Hands-on Lab

📝

Design a CI/CD Pipeline

Sketch a Jenkinsfile that tests, builds a Docker image tagged with the build number, and pushes it
Add a staging deploy, an approval gate, then a production deploy
Add a post failure notification and a docker logout in always

✅

Official Solution

groovy

stages {
stage('Test')            { steps { sh 'npm ci && npm test' } }
stage('Build & Push')    { steps { sh 'docker build -t myapp:${BUILD_NUMBER} . && docker push myapp:${BUILD_NUMBER}' } }
stage('Deploy Staging')  { steps { sh './deploy.sh staging myapp:${BUILD_NUMBER}' } }
stage('Approve')         { steps { input message: 'Ship to prod?' } }
stage('Deploy Prod')     { steps { sh './deploy.sh production myapp:${BUILD_NUMBER}' } }
}

The unique image tag makes every deploy traceable and easy to roll back.

🧠 Knowledge Check

Knowledge Check

Why tag a Docker image with the build number instead of just 'latest' in a CI/CD pipeline?

It builds fasterIt gives each build a unique, traceable tag so you know exactly what's deployed and can roll backlatest is not allowedIt reduces image size

Knowledge Check

What does the input step do in a Jenkins pipeline?

Reads a file from diskPauses the pipeline to wait for human approval before continuingInstalls dependenciesLogs into Docker

💼 Interview Preparation

Interview Q&A

Describe a complete CI/CD pipeline you've designed or would design in Jenkins.

Summary

You’ve completed the Jenkins track: architecture, setup and jobs, pipelines as code, and now a full CI/CD pipeline with Docker, registry push, and an approval gate. You can automate delivery end to end. Next, we step into the frontier: Agentic AI for DevOps.

Up Next

Introduction to Agentic AI

You've mastered this lesson. Continue your journey to becoming a DevOps Engineer.

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