tech-docs

Jenkins

Installation

Docker Run

Pull from Docker Hub:

docker pull jenkins/jenkins:lts-alpine

Run from command line:

docker run -d -v jenkins_home:/var/jenkins_home -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts-alpine

Access Jenkins via a web browser:

http://localhost:8080/

Unlock Jenkins by checking for the key in the logs:

docker logs [container]

Docker Compose

Another way to run Jenkins is using Docker Compose.

.env

# Prefix for image names, container names and volume names
COMPOSE_PROJECT_NAME=custom

# Desired version of Jenkins (Official Docker image)
JENKINS_VERSION=lts-alpine

# Tag for the custom Jenkins image
PROJECT_JENKINS_VERSION=1.0

docker-compose.yml

version: '3.1'
services:
  jenkins:
    build:
      context: ./jenkins
      args:
        JENKINS_VERSION: lts-alpine
    image: ${COMPOSE_PROJECT_NAME:-custom}_jenkins:${PROJECT_JENKINS_VERSION:-latest}-${JENKINS_VERSION:-latest}
    restart: always
    security_opt:
      - no-new-privileges:true
    ports:
      - "8080:8080"
      - "50000:50000"
    volumes:
      - jenkins_home:/var/jenkins_home
      - /var/run/docker.sock:/var/run/docker.sock:ro
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "3"
volumes:
  jenkins_home:

Note: The bind mount of /var/run/docker.sock allows Docker commands to be used from Jenkins but it is NOT a recommended practice. This is explained in a separate document.

Setting up a Reverse Proxy

A reverse proxy might be required, certainly in the case of an HTTPS requirement.

The following links might prove useful:

• Jenkins behind an NGinX reverse proxy

Running Hello World

Once Jenkins is installed it is time to create the simplest possible job!

https://code-maven.com/jenkins-pipeline-hello-world

pipeline {
    agent { label 'master' }
    stages {
        stage('build') {
            steps {
                echo "Hello World!"
            }
        }
    }
}

Other examples:

https://jenkins.io/doc/pipeline/tour/hello-world/

Running Docker Containers

I have made some notes on running Docker containers from inside Jenkins via the Docker socket.

Running AWS CLI Commands

I have made some notes on using the AWS CLI from inside Jenkins, optionally using a custom Docker image.

Running on AWS ECS

Here’s a couple of articles relating to the use of Jenkins on ECS:

Set up a build pipeline with Jenkins and Amazon ECS on AWS Blogs (Devops)

Let’s talk best-practice Jenkins on AWS ECS on Reddit (r/devops)

Job Triggers

Build Periodically

Include the relevant code in the pipeline script.

pipeline {
    agent ...
    triggers {
        cron('10 4 * * *')
    }
    ...
}

Build Dependencies

Include the relevant code in the pipeline script.

pipeline {
    agent ...
    triggers {
        upstream(upstreamProjects: 'job1, job2', threshold: hudson.model.Result.SUCCESS)
    }
    ...
}

GitHub Triggers

I have made some notes on GitHub hooks so that builds can be triggered when changes are pushed to GitHub.

URL Triggers

The URLTrigger plugin can be used to trigger jobs when a URL changes.

Email Notifications

I have made some notes on configuring email notification from inside Jenkins.

Pipeline Examples

I’ve created some examples which include the use of Docker and Git.

Reference

A few useful links about Jenkins Pipelines:

• How to Use the Jenkins Declarative Pipeline

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