Syntax Of Jenkins Declarative Pipeline To Build & Push Docker Image

The following Declarative Pipeline can be used to build and docker push the docker image to DockerHub.

pipeline {
    agent any 
    
    tools {
        // Specify Maven tool with version 3.8.6
        maven "maven 3.8.6"
    }

    stages {
        stage('Code Checkout') {
            steps {
                // Git checkout step
                git credentialsId: '<Git Credentials>', url: '<GitHub URL>'
            }
        }

        stage('Building the Code') {
            steps {
                // Maven clean and package step
                sh "mvn clean package"
            }
        }

        stage('Build the Image') {
            steps {
                // Docker build step, naming the image using DockerHub repository name and build number
                sh "docker build -t <dockerhubname>/<image name>:${BUILD_NUMBER} ."
            }
        }

        stage('Login and Push the Image') {
            steps {
                // Docker login step
                sh "docker login -u <Username> -p <password>"
                // Docker push step, pushing the image with tagged with build number to DockerHub repository
                sh "docker push <dockerhubname>/<image name>:${BUILD_NUMBER}"
            }
        }
    }
}

Explanation Of Jenkins Code

• agent any: This specifies that the pipeline can run on any available agent. An agent is a worker machine on which Jenkins runs its jobs.
• tools: This block defines the tools required for the pipeline. Here, Maven is specified with version 3.8.6.
• stages: This block defines the different stages of the pipeline.
  • Code Checkout: This stage checks out the code from the specified Git repository using the provided credentials.
  • Building the Code: In this stage, the Maven build is performed with mvn clean package.
  • Build the Image: Here, the Docker image is built using the Dockerfile present in the repository. The -t option is used to tag the image with the specified DockerHub repository name, image name, and build number.
  • Login and Push the Image: This stage handles logging into DockerHub using provided credentials and then pushes the built Docker image to the specified DockerHub repository with the tagged build number.

Make sure to replace <placeholders> with your actual values, such as <Git Credentials>, <GitHub URL>, <dockerhubname>, <image name>, <Username>, and <password>.

Jenkins Declarative Pipeline is a more recent addition to Jenkins as a code pipeline definition approach. It offers a more simplified and structured way of defining your pipelines compared to the traditional scripted pipeline syntax.