️ Jenkins CI/CD

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tags:

• dev-tools
• devops

• sysadmin

  Jenkins Sysadmin Cheatsheet

Description: Jenkins is an open-source automation server for building, testing, and deploying software. It supports 1800+ plugins for integration with virtually any tool in the CI/CD toolchain. Written in Java, it runs as a standalone servlet or in containers. Jenkins — это open-source сервер автоматизации для сборки, тестирования и деплоя ПО. Поддерживает 1800+ плагинов для интеграции с любым инструментом CI/CD.

Status: Actively maintained. Alternatives: GitHub Actions (SaaS, GitHub-native), GitLab CI/CD (built-in), Drone CI (container-native), Woodpecker CI (Drone fork, FOSS), Tekton (Kubernetes-native). Role: DevOps / Build Engineer URL: http://<HOST>:8080

📚 Table of Contents

• 1. Service Management
• 2. Jenkins CLI
• 3. Groovy Script Console
• 4. Pipeline Syntax
• 5. Security
• 6. Logrotate Configuration
• Official Documentation

1. Service Management

Default Ports

Systemd / Systemd

/etc/systemd/system/jenkins.service

systemctl start jenkins   # Start / Запуск
systemctl stop jenkins    # Stop / Остановка
systemctl restart jenkins # Restart / Перезапуск
systemctl status jenkins  # Status / Статус

Logs

• Linux (Systemd): /var/log/jenkins/jenkins.log
• Windows: %JENKINS_HOME%\jenkins.out

2. Jenkins CLI

Download CLI jar from: http://<HOST>:8080/jnlpJars/jenkins-cli.jar

# General Syntax
java -jar jenkins-cli.jar -s http://<HOST>:8080/ -auth <USER>:<TOKEN> <COMMAND>

Common Commands

# Restart Jenkins (Safe)
java -jar jenkins-cli.jar -s ... safe-restart

# List Jobs
java -jar jenkins-cli.jar -s ... list-jobs

# Build Job
java -jar jenkins-cli.jar -s ... build <JOB_NAME> -s -v

# Install Plugin
java -jar jenkins-cli.jar -s ... install-plugin <PLUGIN_ID>

3. Groovy Script Console

URL: http://<HOST>:8080/script

Useful Scripts

Print System Info:

println("Jenkins Version: " + jenkins.model.Jenkins.instance.version)
println("Home: " + System.getenv("JENKINS_HOME"))

Disable Security (Emergency Only!):

def instance = jenkins.model.Jenkins.getInstance()
instance.setSecurityRealm(hudson.security.SecurityRealm.NO_AUTHENTICATION)
instance.setAuthorizationStrategy(hudson.security.AuthorizationStrategy.UNSECURED)
instance.save()

[!CAUTION] This completely disables authentication. Use only as a last resort when locked out. Re-enable security immediately after access is restored. Это полностью отключает аутентификацию. Используйте только как крайнюю меру.

4. Pipeline Syntax

Basic Structure

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                echo 'Building...'
                sh 'make'
            }
        }
        stage('Test') {
            steps {
                echo 'Testing...'
                sh 'make check'
            }
        }
        stage('Deploy') {
            steps {
                echo 'Deploying...'
            }
        }
    }
    post {
        always {
            echo 'Cleanup...'
        }
    }
}

Agents (Docker)

agent {
    docker {
        image 'maven:3.8.1-adoptopenjdk-11'
        args '-v /tmp:/tmp'
    }
}

5. Security

User Database

Located in $JENKINS_HOME/users/.

Reset Admin Password

If locked out, edit $JENKINS_HOME/config.xml and change <useSecurity>true</useSecurity> to false. Restart Jenkins. Если заблокированы, измените true на false в теге <useSecurity>. Перезапустите Jenkins.

6. Logrotate Configuration

/etc/logrotate.d/jenkins

/var/log/jenkins/*.log {
    daily
    rotate 14
    compress
    delaycompress
    missingok
    notifempty
    create 640 jenkins jenkins
    copytruncate
}

[!TIP] Use copytruncate as Jenkins keeps the log file handle open. Используйте copytruncate, так как Jenkins держит файл лога открытым.

Official Documentation

• Jenkins: https://www.jenkins.io/doc/
• Jenkins Pipeline Syntax: https://www.jenkins.io/doc/book/pipeline/syntax/
• Jenkins Plugins Index: https://plugins.jenkins.io/
• Jenkins CLI: https://www.jenkins.io/doc/book/managing/cli/