Jenkins CI/CD Pipeline: A Beginner's Guide
Learn how Jenkins automates building, testing, and deploying applications, and explore how CI/CD pipelines fit into a practical AWS DevOps workflow.
Series: My 90-Day AWS & DevOps Learning Journey (21 articles)
- …
- 21Jenkins CI/CD Pipeline: A Beginner's Guide This article
Jenkins CI/CD Pipeline: A Beginner's Guide
Imagine updating your application, building a Docker image, testing the code, and deploying everything manually every time you make a change.
It works for a small project. But what happens when you need to do it several times a day?
This is the problem CI/CD helps solve.
As I continue learning Docker and AWS, I'm exploring how DevOps engineers automate repetitive tasks instead of performing every step manually. One tool worth understanding is Jenkins.
What Is Jenkins?
Jenkins is an open-source automation server commonly used to build CI/CD pipelines.
It can automate tasks such as:
- Building application code
- Running automated tests
- Building Docker images
- Publishing images to a container registry
- Triggering deployment workflows
Instead of manually repeating these steps, we can define a pipeline that executes them in sequence.
What Do CI and CD Mean?
Continuous Integration (CI) means regularly integrating code changes and automatically validating them through processes such as builds and tests.
Continuous Delivery or Continuous Deployment (CD) takes automation further by preparing changes for release or automatically deploying them, depending on the workflow.
The difference matters: continuous delivery keeps software ready to release, while continuous deployment automatically releases qualifying changes to production.
How Does a Jenkins Pipeline Work?
Consider a developer working on a web application.
A simplified workflow might look like this:
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Developer pushes code
↓
GitHub
↓
Jenkins Pipeline
↓
Build Application
↓
Run Tests
↓
Build Docker Image
↓
Push Image to ECR
↓
Deploy to AWS ECSThis connects several tools I've been learning: Git, Docker, Amazon ECR, and Amazon ECS.
Jenkins coordinates the workflow, while the other tools perform their respective jobs.
What Is a Jenkinsfile?
A Jenkinsfile defines a pipeline as code.
This allows the pipeline to be version-controlled alongside the application.
Here's a simple example:
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pipeline {
agent any
stages {
stage('Build') {
steps {
echo 'Building application...'
}
}
stage('Test') {
steps {
echo 'Running tests...'
}
}
stage('Package') {
steps {
echo 'Packaging application...'
}
}
}
}This example demonstrates the pipeline structure. It prints messages rather than performing a real build or running tests.
In an actual project, these stages would contain commands appropriate for the application's programming language and build tools.
Why Is CI/CD Useful?
Imagine fixing a bug in your application.
Without automation, you might need to build the application, run tests, create a Docker image, and deploy the updated version manually.
With a properly configured pipeline, these steps can run automatically when code changes meet the configured trigger conditions.
This can help teams achieve:
- Faster feedback on code changes
- More consistent build and test processes
- Fewer repetitive manual steps
- More reliable releases
- Better visibility into pipeline failures
However, automation doesn't guarantee that every deployment will succeed. Good testing, security controls, monitoring, and rollback strategies are still important.
Where Does AWS Fit In?
Jenkins can work with AWS services to automate cloud deployments.
For example:
- Amazon ECR: Store Docker images.
- Amazon ECS: Run containerized applications.
- Amazon EC2: Provide virtual machines for workloads or self-managed Jenkins infrastructure.
- AWS IAM: Control access to AWS resources.
Credentials should be managed securely rather than hardcoded into a Jenkinsfile. AWS deployments should use appropriately scoped permissions and secure credential-management practices.
A Beginner-Friendly Hands-On Project
A useful next step is to create a small pipeline for a simple web application.
- Store the application code in GitHub.
- Create a basic Jenkins pipeline.
- Configure a build stage.
- Add a test stage.
- Build a Docker image.
- Extend the pipeline to push the image to Amazon ECR.
- Explore deploying the image to ECS.
Start with the build and test stages. Add AWS deployment only after the basics work.
This approach helps you understand the complete workflow without trying to learn every tool at once.
My Learning Journey
My recent learning has moved from containers to cloud deployment. Now I'm exploring how automation connects those pieces.
Docker helps package an application. ECR stores its image. ECS runs the container. Jenkins can coordinate the steps that build, test, and deploy it.
The goal isn't just to learn individual tools. It's to understand how they work together to deliver software.
💬 Let's Discuss
I'd love to hear from people learning or working in DevOps:
When you first learned CI/CD, which part was the most challenging: writing a Jenkinsfile, configuring GitHub integration, building Docker images, managing credentials, or deploying to AWS?
If you're a beginner, which part of this workflow would you like to build as your first hands-on project?
Series: My 90-Day AWS & DevOps Learning Journey (21 articles)
- …
- 21Jenkins CI/CD Pipeline: A Beginner's Guide This article
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