Managing Global Configuration

1. Configuring System Settings

Setting	Description	Default Value	Notes
System Admin Email	Admin email address for system notifications	None	Required for email notifications
Global Tool Configuration	Define global tools like JDK, Maven, etc.	None	Used by jobs to access tools
Global Security	Configure security settings for the entire Jenkins instance	None	Includes authentication and authorization settings
Global Environment Variables	Environment variables available to all jobs	None	Can be overridden per job

Example: Setting Global Environment Variables

environment {
  JAVA_HOME = "/usr/lib/jvm/java-11-openjdk"
  MAVEN_HOME = "/opt/maven"
}

Note: Changes to global settings may require a Jenkins restart to take effect.

2. Setting Global Properties

Property	Value	Description
JENKINS_URL	`http://localhost:8080`	Base URL for Jenkins instance
JAVA_HOME	`/usr/lib/jvm/java-11-openjdk`	Path to Java installation
JENKINS_HOME	`/var/lib/jenkins`	Directory where Jenkins stores data

Example: Setting Global Properties via CLI

java -Djenkins.url=http://localhost:8080 -jar jenkins.war

Note: Global properties can also be set through the Jenkins web UI under Manage Jenkins > Configure System.

3. Configuring JDK Installations

Property	Value	Description
JDK Name	`jdk-11`	Name used to identify the JDK installation in Jenkins configuration
Java Home	`/usr/lib/jvm/java-11-openjdk`	Path to the JDK installation directory

Example: Adding JDK to Jenkins

sudo apt update
sudo apt install openjdk-11-jdk

Example: Configure JDK in Jenkins UI

Manage Jenkins > Global Tool Configuration > JDK

4. Configuring Maven Installations

Property	Value	Description
maven.home	`/opt/maven`	Path to the Maven installation directory
maven.version	`3.9.6`	Version of Maven to use

Example: Setting up Maven in Jenkins

pipeline {
    agent any
    tools {
        maven 'apache-maven-3.9.6'
    }
    stages {
        stage('Build') {
            steps {
                sh 'mvn clean compile'
            }
        }
    }
}

Note: Ensure that the Maven installation is correctly configured in Jenkins global tool configuration before using it in pipelines.

5. Configuring Git Installations

Property	Values	Description
git.installation.path	`/usr/bin/git`	Path to the Git executable on the system
git.installation.name	`Default Git`	Name identifier for the Git installation

Example: Git Installation Configuration

import hudson.plugins.git.GitTool
import hudson.tools.InstallableTool
import jenkins.model.Jenkins

def gitTool = new GitTool(
    name: "Custom Git",
    home: "/usr/local/bin/git"
)

Jenkins.instance.getDescriptor(GitTool).setInstallations([gitTool])
Jenkins.instance.save()

Note: Ensure the Git executable path is accessible from Jenkins' execution environment.

6. Setting Usage Statistics Preferences

Example: Configure Usage Statistics

import jenkins.model.Jenkins

def jenkins = Jenkins.getInstance()
def usageStats = jenkins.getUsageStatistics()

// Enable sending usage statistics
usageStats.setCollectUsageStats(true)

// Save the configuration
jenkins.save()

Property	Values	Description
collectUsageStats	`true` / `false`	Controls whether Jenkins collects and sends usage statistics to the Jenkins project.
lastSentDate	`ISO 8601 date string`	Date when the last statistics were sent.

Note: Usage statistics are sent once per day, and can be disabled at any time via the UI or API.

7. Configuring Email Notification

Property	Value	Description
hudson.model.Jenkins.adminAddress	`jenkins@example.com`	Admin email address for system notifications
hudson.plugins.email.ExtendedEmailPublisher.defaultRecipients	`team@example.com`	Default recipients for email notifications
hudson.plugins.email.ExtendedEmailPublisher.defaultSubject	`Build ${BUILD_NUMBER} ${BUILD_STATUS}`	Default subject line for emails

Example: Configure Email Settings via Jenkins UI

Manage Jenkins > Configure System > E-mail Notification

Example: Using Jenkinsfile for Email Configuration

pipeline {
  agent any
  post {
    always {
      emailext (
        subject: "Build ${BUILD_NUMBER} ${BUILD_STATUS}",
        to: "team@example.com",
        body: "Build details available at ${BUILD_URL}"
      )
    }
  }
}

Note: Ensure SMTP settings are configured under Manage Jenkins > Configure System for email delivery to work properly.

8. Setting Build Record Retention

Property	Values	Description
buildsToKeep	`0`	Number of builds to keep. 0 means unlimited.
daysToKeep	`0`	Number of days to keep builds. 0 means unlimited.
artifactDaysToKeep	`-1`	Number of days to keep artifacts. -1 means use `daysToKeep`.
artifactNumToKeep	`-1`	Number of artifacts to keep. -1 means use `buildsToKeep`.

Example: Configure retention in Jenkinsfile

pipeline {
    agent any
    options {
        buildDiscarder logRotator(daysToKeep: 7, numToKeep: 5)
    }
    stages {
        stage('Build') {
            steps {
                echo 'Building...'
            }
        }
    }
}

Note: The logRotator option is part of the pipeline directive and applies to all builds in that pipeline.

9. Configuring Workspace Cleanup Policies

Policy	Description	Configuration	Notes
Log Rotation	Automatically deletes old build logs to save space	`buildsToKeep`: Number of builds to keep `daysToKeep`: Days to keep logs	Default: 10 builds, 7 days
Workspace Cleanup	Deletes workspace directories after builds	`cleanAfterSuccessfulBuild`: Boolean `cleanAfterFailedBuild`: Boolean	Can be configured per job or globally
Artifacts Retention	Manages retention of build artifacts	`artifactArchivingDisabled`: Boolean `maxBuildsToKeep`: Number of builds to archive	Artifacts are stored in `$JENKINS_HOME/artifacts`

Example: Global Workspace Cleanup Configuration

// Groovy script to configure global workspace cleanup
import jenkins.model.Jenkins

def jenkins = Jenkins.instance
jenkins.setBuildsToKeep(5)
jenkins.setDaysToKeep(3)
jenkins.setArtifactArchivingDisabled(false)
jenkins.setMaxBuildsToKeep(10)

// Save configuration
jenkins.save()

Note: Workspace cleanup policies can be overridden at the job level using the Build Environment section in job configuration.

Warning: Disabling workspace cleanup can lead to disk space exhaustion over time.

10. Setting Global Pipeline Libraries

Property	Value	Description
name	`my-library`	Name of the library to be referenced in pipelines
retrievalMethod	`modernSCM`	Method used to retrieve the library (e.g., `modernSCM`, `legacy`)
scm	`{url: 'https://github.com/example/my-library.git'}`	Source control management configuration for the library
defaultVersion	`master`	Default branch or tag to use if not specified in pipeline
implicit	`false`	Whether the library is automatically available to all pipelines
allowOverride	`true`	Allows individual pipelines to override the library version

Example: Global Library Configuration

library(
  name: 'my-library',
  version: 'v1.0',
  implicit: false,
  allowOverride: true
)

Note: Libraries must be defined in the Jenkins Global Configuration under Manage Jenkins > Configure System.

Warning: Ensure the library repository is accessible to Jenkins and has proper credentials configured if required.