Groovy Scripting for Jenkins Pipelines: Advanced Techniques

This guide dives deeper into Groovy scripting for Jenkins pipelines, exploring conditional statements, looping, functions, and data structures. We’ll provide examples and explain how these techniques enhance pipeline control and data management.

Conditional Statements:

if and else: Control the pipeline flow based on conditions.

node {
  stage('Build') {
    sh 'mvn clean compile'
    if (sh(returnStatus: true, script: 'mvn test').exitCode == 0) {
      echo 'Tests passed, proceeding...'
    } else {
      echo 'Tests failed, notifying developers...'
      // Send notification (example omitted)
      // Optionally, retry the build
    }
  }
}

Explanation:

The if statement checks if the mvn test command exits with code 0 (success).
If successful, the pipeline continues. Else, it sends a notification and could potentially retry the build (not shown).
switch: Make decisions based on multiple conditions.

stage('Environment') {
  def envName = env.ENVIRONMENT // Get environment from Jenkins parameters
  switch (envName) {
    case 'dev':
      echo 'Deploying to development environment...'
      // Deploy to dev server (example omitted)
      break
    case 'test':
      echo 'Deploying to testing environment...'
      // Deploy to test server (example omitted)
      break
    default:
      echo "Invalid environment: ${envName}"
      error 'Exiting pipeline...'
  }
}

Explanation:

The switch statement evaluates the envName variable and executes the corresponding code block for “dev” or “test” environments.

Looping:

for loop: Iterate over a list of items.

stage('Unit Tests') {
  def testFiles = ['test/unit/MyClassTest.groovy', 'test/unit/AnotherTest.groovy']
  for (file in testFiles) {
    sh "groovy ${file}" // Execute each unit test file
  }
}

Explanation:

The for loop iterates through the testFiles list, executing the Groovy script for each unit test file.

Working with Functions:

Create reusable functions for code modularity.

def notify(message) {
  echo "Sending notification: ${message}"
  // Implement notification logic (e.g., email, Slack)
}

stage('Build') {
  sh 'mvn clean compile'
  if (sh(returnStatus: true, script: 'mvn test').exitCode != 0) {
    notify('Build failed, unit tests failed!')
  }
}

Explanation:

The notify function takes a message and sends a notification (implementation details omitted).
The Build stage utilizes the notify function for a cleaner script.

Data Structures:

Lists: Store ordered collections of items.

def buildArtifacts = ['build.jar', 'reports.zip']

stage('Archive Artifacts') {
  archiveArtifacts artifacts: buildArtifacts
}

Explanation:

The buildArtifacts list defines files to be archived by Jenkins.
Maps: Store key-value pairs of data.

def config = [
  'server' : 'server1.example.com',
  'port'   : 8080
]

stage('Deploy') {
  sh "scp build.jar ${config['server']}:${config['port']}"
}

Explanation:

The config map stores server details used in the scp command for deployment.

Sample Output:

The output will vary depending on your specific pipeline execution. Here’s an example with successful tests and notification function (implementation details omitted):

Running on Jenkins in container ...
Stage 'Build'
mvn clean compile
Stage 'Unit Tests'
Sending notification: Build failed, unit tests failed!
[Pipeline] End of Pipeline

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Groovy Scripting for Jenkins Pipelines: Advanced Techniques

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