CentOS Jenkins如何使用Docker容器

Prerequisites: Install Docker on CentOS
Before using Docker to deploy Jenkins, ensure Docker is installed and running on your CentOS system. Run the following commands to install Docker:

sudo yum update -y
sudo yum install -y yum-utils device-mapper-persistent-data lvm2
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo yum install -y docker-ce docker-ce-cli containerd.io
sudo systemctl start docker
sudo systemctl enable docker

Verify the installation with docker --version.

Step 1: Pull the Jenkins Docker Image
Fetch the official Jenkins Long-Term Support (LTS) image from Docker Hub (recommended for production stability):

docker pull jenkins/jenkins:lts

This command downloads the latest stable Jenkins image to your local machine.

Step 2: Run the Jenkins Container
Start a Jenkins container with port mappings and volume persistence. Use this command (adjust paths as needed):

docker run -d \
  --name jenkins \
  -p 8080:8080 \          # Map host port 8080 to container port 8080 (web interface)
  -p 50000:50000 \        # Map host port 50000 to container port 50000 (agent communication)
  -v jenkins_home:/var/jenkins_home \  # Persistent volume for Jenkins data (Docker-managed)
  -v /var/run/docker.sock:/var/run/docker.sock \  # Allow Jenkins to control host Docker (for Docker-in-Docker)
  jenkins/jenkins:lts

Key parameters:

• -d: Run the container in detached (background) mode.
• --name jenkins: Assign a memorable name to the container.
• Volume mounts (-v): Ensure Jenkins configuration/data persists even if the container is deleted.

Step 3: Access Jenkins Initial Setup
Open a browser and navigate to http://<your_server_ip>:8080. You’ll see the Jenkins unlock page. Retrieve the initial admin password by running:

docker exec jenkins cat /var/jenkins_home/secrets/initialAdminPassword

Copy the displayed password and paste it into the unlock form. Proceed to install recommended plugins (e.g., Git, Pipeline, Docker) to enable core CI/CD functionality.

Step 4: Configure Jenkins for Docker Integration
To allow Jenkins to build/push Docker images or run containers, install the Docker Plugin:

1. Go to Manage Jenkins > Manage Plugins > Available.
2. Search for “Docker Plugin” and click Install without restart.
3. Configure the Docker cloud: Navigate to Manage Jenkins > Configure System > Cloud > Add a new cloud > Docker.
4. Set the Docker Host URI to unix:///var/run/docker.sock (enables communication with the host Docker daemon).
5. Add credentials for Docker registries (e.g., Docker Hub) if pushing images.

Step 5: Create a Sample Jenkins Pipeline
Create a new Pipeline job to automate building/pushing a Docker image. Example pipeline script (Jenkinsfile) in your repository:

pipeline {
    agent any
    stages {
        stage('Checkout') {
            steps {
                git url: 'https://github.com/your-repo/your-app.git', branch: 'main'  // Replace with your repo
            }
        }
        stage('Build Docker Image') {
            steps {
                script {
                    def imageName = "your-dockerhub-username/your-app:${env.BUILD_ID}"
                    docker.build(imageName)  // Build image with BUILD_ID as tag
                }
            }
        }
        stage('Push to Docker Hub') {
            steps {
                script {
                    def imageName = "your-dockerhub-username/your-app:${env.BUILD_ID}"
                    docker.withRegistry('https://registry.hub.docker.com', 'docker-hub-credentials') {  // Use credentials ID from step 4
                        docker.image(imageName).push()  // Push image to Docker Hub
                    }
                }
            }
        }
    }
}

This pipeline checks out code, builds a Docker image, and pushes it to Docker Hub. Replace placeholders (e.g., your-repo, your-dockerhub-username) with your actual values.

Optional: Use Docker Compose for Easier Management
For simplified container orchestration, create a docker-compose.yml file:

version: '3'
services:
  jenkins:
    image: jenkins/jenkins:lts
    container_name: jenkins
    ports:
      - "8080:8080"
      - "50000:50000"
    volumes:
      - jenkins_home:/var/jenkins_home
      - /var/run/docker.sock:/var/run/docker.sock
volumes:
  jenkins_home:

Start the container with docker-compose up -d and manage it using docker-compose commands (e.g., docker-compose stop, docker-compose logs).