CONTINUOUS INTEGRATION AND DEPLOYMENT
Published: 2024-04-06 17:53:50

What is CI/CD Pipeline?

The term “CI/CD pipeline” refers to the Continuous Integration/Continuous Delivery pipeline. 

A Pipeline refers to a series of automated steps that software goes through from when it is initially written to when it is deployed for production. It is like an assemble line in a factory, but for software.
Here's a simplified breakdown:
Imagine each step as a different station on the assembly line. Each station performs a specific task on the software.


The code goes through these stations one by one. These could be tasks like:
Building the code: This translates the code into a format the computer can understand.
Running tests: This checks if the code works as expected and identifies any errors.
Deploying the code: This puts the new version of the software in its intended environment (e.g., website, app store).


Once a step is complete, the software automatically moves on to the next one. This continues until all the steps are finished, and the software is ready to be used.
Think of it like this: Each step in the pipeline is like a filter, ensuring the quality and functionality of the software before it reaches the final destination.
Here are some key points about CI/CD pipelines:
They are automated: This eliminates the need for manual intervention and reduces the risk of human error.
They are customizable: Different projects may have different needs, so the specific steps in the pipeline can be tailored accordingly.
They are efficient: They streamline the software development process, allowing for faster and more frequent releases.
By using CI/CD pipelines, software developers can focus on writing code while the pipeline takes care of the repetitive and error-prone tasks, ultimately leading to better quality software delivered faster.




BENEFITS OF CONTINUOUS DELIVERY 

Prepares code for releases 
Automates the steps that are needed to deploy a build 


PHASES OF CONTINUOUS INTEGRATION

Plan 
Code 
Build 
Test 

PHASES OF CONTINUOUS DELIVERY 
Release 
Deploy 
Operate 

CI/CD Pipeline with Jenkins

Jenkins is a popular open-source automation server commonly used for implementing CI/CD pipelines. It provides a platform to define and orchestrate the various stages involved in building, testing, and deploying software.
Here's an overview of how a CI/CD pipeline might be built with Jenkins:


1. Stages:
The pipeline is typically divided into stages, each representing a specific phase in the software development lifecycle. Common stages include:
Code checkout: Obtains the latest code from the version control system (e.g., Git).
Build: Compiles or packages the code into a deployable format (e.g., executable, container image).
Unit testing: Runs automated tests to ensure individual code units function correctly.
Integration testing: Tests the combined functionality of different components within the application.
Deployment: Deploys the application to the desired environment (e.g., development, staging, production). This might involve container image deployment to Kubernetes or deploying a package to a server using tools like Ansible or Chef.
Post-deployment actions: Optionally, perform tasks like sending notifications, running acceptance tests, or collecting performance metrics.
2. Configuration:
Each stage of the pipeline is defined in a Jenkinsfile, written in a declarative or scripted language. This file specifies the commands and tools to be used for each step.
Jenkins provides a web interface for configuring pipelines, managing jobs, and viewing build history.
3. Benefits of using Jenkins for CI/CD:
Open-source and free: Reduces the cost of implementing a CI/CD solution.
Flexible and customizable: Allows tailored pipelines for different project needs.
Extensive plugin ecosystem: Integrates with various tools and technologies used in software development.
Large community and resources: Offers abundant support and knowledge sharing.
4. Additional Considerations:
While Jenkins is a popular choice, other CI/CD tools like GitLab CI/CD, CircleCI, and Travis CI are also available.
The specific tools and technologies used within a CI/CD pipeline will vary depending on the project requirements and preferences.
Overall, utilizing Jenkins for CI/CD pipelines enables teams to automate the software development process, leading to faster release cycles, improved code quality, and increased efficiency.

What is Continuous Integration (CI)?

Continuous Integration (CI) is a software development practice that involves regularly integrating code changes from multiple contributors into a shared repository. The primary aim of CI is to detect and address integration issues early in the development process. This is achieved by automating the build and testing of the codebase whenever changes are made. 
Key aspects of CI: 
Process: 
Frequent code commits: Developers regularly commit their code changes to the shared repository, often through a version control system like Git.
Automated Builds and Tests: After each commit, an automated build process kicks in. This involves compiling the code, running unit tests, and potentially other verification steps.
Early feedback: The build process provide immediate feedback to the developer, indicating if their changes have introduced any conflicts or regressions. 
Faster Delivery: By continuously integrating code and catching issues early, CI facilitates quicker and smoother release cycles. 
Benefits of CI:
Improved Code Quality: Continuous feedback helps developers identify and fix bugs early in the development process, leading to higher-quality software.
Increased Efficiency: By catching defects early, CI reduces the time and effort spent on fixing issues later in the development cycle.
Enhanced Collaboration: CI encourages a collaborative development environment where code changes are frequently integrated and reviewed, leading to better communication and coordination among developers.
CI Tools and Services:
Several tools and services can be used to implement continuous integration, including:
Jenkins: A popular open-source CI/CD server that automates the build, test, and deployment process.
CircleCI: A cloud-based continuous integration and continuous delivery platform.
Travis CI: Another cloud-based CI platform that integrates with various code hosting services.
What is Continuous Delivery (CD)?

Continuous delivery (CD) is the bridge between developing software and making it readily available to your users. It's where you take the changes in your code and prepare them for deployment (release) to a production environment – the version users actually interact with.

For example: You've built a new feature or fixed a bug in your code (think building a car). Now, in CD, you're detailing exactly what features and bug fixes will be delivered to your users (deciding which features go into the final car model) and when (scheduling its release). The ultimate goal is to automate this process, making deployments seamless and consistent.

Combining Forces: CI/CD Pipeline Magic
When continuous integration (CI) joins forces with CD, you get a fully automated pipeline that continuously integrates code changes, tests them thoroughly, and prepares them for deployment, all in a streamlined sequence. This CI/CD pipeline empowers your team to deploy code rapidly and efficiently, leading to:
Increased Agility: You can adapt quickly to changing needs and release new features faster.
Enhanced Productivity: Automation frees up time for your team to focus on more strategic initiatives.
Boosted Confidence: Frequent deployments with minimal risks provide greater confidence in your codebase.
Best Practices for CI/CD Pipeline Security
Implementing CI/CD comes with its own set of security considerations:
Secure authentication: Use strong passwords and one-time passwords for sensitive systems.
Secret management: Store credentials securely and avoid hardcoding them in code.
Least privilege: Grant access only to necessary resources.
Machine identity validation: Ensure only authorized machines can access the pipeline.
Regular scans: Monitor code and builds for vulnerabilities.
By adopting these best practices, you can safeguard your CI/CD pipeline and enjoy the benefits of faster, more reliable deployments.

4. Create a Pipeline Job
Select and define what Jenkins job that is to be created.
Select Pipeline, give it a name and click OK.
Scroll down and find the pipeline section.
Either directly write a pipeline script or retrieve the Jenkins file from SCM (Source Code Management).

5. Configure and Execute a Pipeline Job With a Direct Script
Choose Pipeline script as the Destination and paste the Jenkins file content in the Script from the GitHub.
Click on Save to keep the changes.
Now click on the Build Now to process the build.
To check the output, click on any stage and click Log; a message will appear on the screen.

6. Configure and Execute a Pipeline With SCM
Copy the GitHub repository URL by clicking on Clone or download.

Now, click on Configure to modify the existing job.
Scroll to the Advanced Project Options setting and select Pipeline script from the SCM option.
Paste the GitHub repository URL here.
Type Jenkinsfile in the Script, and then click on the Save button.
Next, click on Build Now to execute the job again.
There will be an additional stage, in this case, i.e., Declaration: Checkout SCM.
Click on any stage and click on Log.
After you have grasped all the essential steps to build a CI/CD pipeline using Jenkins, a hands-on demonstration will serve as the icing on the cake.


Demo - To Build a CI/CD Pipeline With Jenkins
Go to your Jenkins Portal:
Click on ‘Create a job’.
In the item name dialog box, you may enter the ‘pipeline’.
Select the pipeline job type in the list below.
Click on OK.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/y04t1yllm3dcx9lr2m1e.png)





A configuration related to the pipeline opens on the screen.
Scroll down on that page.
There in the dialog box, choose GitHub+Maven.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1m00ria1jxt1dr5p0d5e.png)


Some steps will appear on the screen. The next step is to integrate the Jenkins file into the Version Control system.
So, to do that, you must:
Select ‘Pipeline script from SCM’.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/19rnuxg1oygwbbep7ug6.png)

Then in the SCM dialog box, select Git.
‘Jenkins file’ is the name of the Script.
Add the Git repository URL.
You can add the credentials if any.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/j1h964zqse231s3g39dl.png)

The credentials can be added with the help of the ‘Add’ option.
Then save the configuration
A page now appears on the screen that gives you various options like ‘Build Now’, ‘Delete Pipeline’, ‘Configure’, etc.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/oqdw7wqlxnptn4v41yeb.png)

Click on the Build Now option.
The pipeline will start downloading. The checkout will be visible on the screen and you can see the build being complete on the screen.
PLATFORMS AND TOOLS 
Jenkins: A CI/CD software installed on a server where the centra; build tales place 
Circle CI A platform that can be used to implement devops practices. It perfroms depliments for continuous delivery and you define workflows insicde a circle.yaml file
Travis CI: This is a CI service that helps you automate your build test and deploy gathered workflow
GitHub Actions: A platform built directly into GitHub that allows you to automate workflows for your project. These workflows can include building, testing, and deploying your code. You define these workflows in YAML files within your GitHub repository.


CI/CD Automation with Benefits:
Faster feedback: CI tools automate testing and building code upon changes, enabling quicker response to updates.
Improved quality: Continuous testing catches errors early, leading to higher code quality.
Reduced risk: Smaller, more frequent integrations minimize the risk of breaking changes.
Faster deployments: CI/CD pipelines streamline delivery, getting features to users sooner.
Source Code Management Explained:
Tracking versions: SCM tools (Version Control Systems) track code changes over time.
Centralized vs. Distributed: Centralized systems store code in a central location, while distributed systems give developers local copies.
Social Coding: Sharing code openly encourages collaboration and code reuse, with pull requests managing contributions.