Jenkins is a Java-based, open-source automation server that can be utilized to automate various tasks related to building, testing, deploying, and distributing software projects. Being written in Java, it is platform-independent, making it accessible on different operating systems.
With Jenkins, we can automate our Continuous Integration (CI) and Continuous Deployment (CD) processes. This enables us to continuously build and test our product during its development, allowing developers to integrate changes into the system rapidly and with consistent quality compared to manual approaches. Through Jenkins, they can achieve this integration much faster, streamlining the development workflow efficiently.
Continuous Integration
Continuous integration (CI) is the practice of automating the integration of code changes from multiple contributors into a single software project. The key goals of continuous integration are to find and address bugs quicker, improve software quality, and reduce the time it takes to validate and release new software updates.
Some Benefits of Continuous Integration
- Enhanced Test Control:
- The CI pipeline automatically runs tests upon triggering.
- Immediate notifications for any code commits that break the build, allowing timely rectification before proceeding.
- Faster Deployment:
- CI streamlines the deployment process, reducing manual intervention and minimizing deployment time.
- Automation of Repetitive Tasks:
- CI automates routine tasks, saving time and effort, and enabling developers to focus on core development tasks.
Continuous Deployment
Continuous Deployment (CD) is a streamlined software release process that validates code changes for correctness and stability, allowing for immediate and autonomous deployment to a production environment. This approach ensures that only reliable and thoroughly tested updates are pushed into the live system without manual intervention.
Continuous Deployment vs. Continuous Delivery
The distinction between continuous deployment and continuous delivery can be confusing due to the terminology.
In the continuous delivery phase, developers review and merge code changes, creating a deployable artifact. This artifact is moved to a staging or pre-production environment, where it undergoes thorough testing and validation. The continuous delivery process ensures that the software is always in a deployable state and ready to be released to production. However, the actual deployment to the production environment is typically triggered manually or through an approval process, giving the development team more control over the final release.
On the other hand, continuous deployment takes automation one step further. Once the code changes have passed all tests and validations in the staging environment, the continuous deployment process automatically and autonomously pushes the changes into the production environment. This automation eliminates the need for manual intervention, reducing the time between development and actual deployment to the live system.
What is Jenkins?
Jenkins is a Java-based, open-source automation server that can be utilized to automate various tasks related to building, testing, deploying, and distributing software projects. Being written in Java, it is platform-independent, making it accessible on different operating systems.
With Jenkins, we can automate our Continuous Integration (CI) and Continuous Deployment (CD) processes. This enables us to continuously build and test our product during its development, allowing developers to integrate changes into the system rapidly and with consistent quality compared to manual approaches. Through Jenkins, they can achieve this integration much faster, streamlining the development workflow efficiently.
What is Jenkins used for?
Jenkins is primarily used as an automation server in software development to facilitate Continuous Integration (CI) and Continuous Deployment (CD) processes. Its main purpose is to automate various tasks and workflows to streamline the software development lifecycle.
- Continuous Integration (CI): Jenkins is extensively used for CI, where it automates the process of integrating code changes from multiple developers into a shared repository. Whenever a developer commits code, Jenkins triggers a build process, compiling the code and running automated tests. This enables early detection of integration issues and ensures that the codebase remains in a continuously integrated and functional state.
- Continuous Deployment (CD): Jenkins also plays a significant role in CD by automating the deployment of software to different environments. After the code passes all tests in the CI phase, Jenkins can automatically deploy the application to staging or production environments, reducing manual intervention and enabling faster, more reliable deployments.
- Task Automation: Beyond CI/CD, Jenkins can be customized to automate a wide range of tasks in the software development process. It can perform tasks like code analysis, generating reports, triggering external tools, sending notifications, and more, all based on predefined configurations and triggers.
- Build Management: Jenkins acts as a centralized platform for managing software builds across various platforms and configurations. It can handle different build tools and environments, ensuring consistent and reproducible build results.
- Version Control: Jenkins seamlessly integrates with version control systems like Git, SVN, and others. It can monitor code repositories for changes and automatically initiate the build and testing processes, promoting efficient collaboration among developers.
In summary, Jenkins is an automation server that revolutionizes software development by automating tasks, enabling faster, more reliable deliveries through efficient CI/CD pipelines.
Jobs
enkins Jobs are a fundamental and essential aspect of Jenkins automation. They represent individual tasks or processes that can be executed within the Jenkins environment. A job in Jenkins is a unit of work that performs a specific set of actions to achieve a particular objective, such as building, testing, deploying, or any other task that needs to be automated.
Jenkins Jobs can be created and configured using the Jenkins Job DSL (Domain-Specific Language), which is typically written in Groovy code. This Job DSL allows for the programmatic creation of Jenkins jobs, enabling developers to define job configurations as code instead of manually configuring them through the Jenkins web interface.
Jenkins Pipelines
Jenkins Pipeline is a powerful feature in Jenkins that allows developers to define and manage their entire Continuous Integration/Continuous Deployment (CI/CD) process as code. It enables the creation of scripted or declarative pipelines that outline the steps involved in building, testing, and deploying software projects. The pipelines are written using either Groovy-based scripting or a more structured, declarative syntax.
There are two main types of Jenkins Pipelines:
- Scripted Pipeline: This type uses a Groovy-based scripting syntax to define the pipeline steps. It provides great flexibility and fine-grained control over the execution flow. However, it can be more verbose and complex compared to declarative pipelines.
- Declarative Pipeline: Declarative pipelines use a more structured and concise syntax. They offer a simplified way of defining pipelines, making it easier to read, maintain, and visualize. Declarative pipelines are recommended for most use cases, especially for those getting started with Jenkins Pipelines.
Jenkinsfile
A Jenkinsfile is a text file that serves as the configuration and definition of a Jenkins Pipeline. It is written in either a scripted or declarative syntax using Groovy, which is a programming language that runs on the Java Virtual Machine (JVM). Here’s an example of what it looks like:
pipeline {
agent any
stages {
stage('Deploy') {
steps {
echo 'Deploying...'
}
}
}
}The post section in a Jenkins Pipeline is used to define steps that should be executed after the main stages of the pipeline have been completed, regardless of whether they were successful, failed, or aborted.
pipeline {
agent any
stages {
stage('Build') {
steps {
// Build steps go here
}
}
stage('Test') {
steps {
// Test steps go here
}
}
}
post {
always {
// These steps will always be executed
echo 'You will always see me'
}
success {
// These steps will be executed only if the pipeline is successful
echo 'I am happy!'
}
failure {
// These steps will be executed only if the pipeline fails
mail to: 'jenkins@tuuple.com',
subject: 'Pipeline failed: ${currentBuild.fullDisplayName}',
body: 'Job ${env.JOB_NAME} is failed. For more detail: ${env.BUILD_URL}'
}
unstable {
// These steps will be executed only if the pipeline was marked as unstable
echo 'What is happening!!'
}
changed {
// These steps will be executed only if the pipeline was previously failing but now is successful
echo 'Good news!'
}
}
}Environment Variables
Jenkins Pipeline exposes environment variables via the global variable env, which is available from anywhere within a Jenkinsfile. Some of the useful environment variables are; BUILD_ID, BUILD_NUMBER, BUILD_URL, JAVA_HOME, JENKINS_URL, JOB_NAME
pipeline {
agent any
environment {
CREDENTIAL = credentials('my-secret-key')
}
stages {
stage('Clone') {
steps {
git branch: 'master', url: 'https://github.com/....', credential: CREDENTIAL
}
}
}
}Jenkins Agents
Jenkins agents, also known as Jenkins slaves, are essential components in the distributed architecture of Jenkins. They enable the execution of jobs on various environments, providing flexibility and scalability to the Jenkins automation system.
pipeline {
agent {
docker { image: 'node:14-alpine' }
}
stages {
stage('Validate') {
steps {
sh 'node --version'
}
}
}
}pipeline {
agent none
stages {
stage('Backend') {
agent {
docker { image: 'maven:3.9.3-sapmachine-17' }
}
steps {
sh 'mvn --version'
}
}
stage('Frontend') {
agent {
docker { image: 'node:14-alpine' }
}
steps {
sh 'node --version'
}
}
}
}
