(Last Updated On: November 1, 2018)

Jenkins is an open source automation server used to automate repetitive tasks that are often encountered in continuous integration and delivery of software. In this guide, we will see how you can run Jenkins server on a Docker container managed via Systemd init system.

If you would prefer running Jenkins on a CentOS 7 or Ubuntu 18.04 instance, use the following guides instead.

How to Install Jenkins on Ubuntu 18.04

How to install Jenkins Server Stable on CentOS 7

This guide is specific for Docker guys who like containerizing applications and any infrastructure management tools.

Running Jenkins Server in Docker – Dependencies

Running Jenkins Server on a Docker has few dependencies that you’ll need to satisfy.

  • Linux or macOS
  • Docker Engine installed and running
  • A user account with sudo privileges

Step 1: Install Docker Engine

Start by installing Docker engine on your base operating system. You can use our previous guide for docker installation.

How to install Docker CE on Ubuntu / Debian / Fedora / Arch / CentOS

After the installation, you can confirm the version installed by running:

$ docker version
Client:
 Version:           18.06.1-ce
 API version:       1.38
 Go version:        go1.10.3
 Git commit:        e68fc7a
 Built:             Tue Aug 21 17:24:51 2018
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          18.06.1-ce
  API version:      1.38 (minimum version 1.12)
  Go version:       go1.10.3
  Git commit:       e68fc7a
  Built:            Tue Aug 21 17:23:15 2018
  OS/Arch:          linux/amd64
  Experimental:     false

Step 2: Add jenkins user

Next is to add Jenkins system user to your server. This user will manage Jenkins service.

sudo groupadd --system jenkins
sudo useradd -s /sbin/nologin --system -g jenkins jenkins
sudo usermod -aG docker jenkins

Ensure this user is added to the docker group.

# id jenkins
uid=999(jenkins) gid=998(jenkins) groups=998(jenkins),999(docker)

Pull the LTS docker image release of Jenkins

$ sudo docker pull jenkins/jenkins:lts

Confirm that the image download was successful.

# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
jenkins/jenkins     lts                 9cff19ad8c8b        3 weeks ago         730MB

Step 3: Create a Jenkins Data directory & container

We need a persistent storage for Jenkins data to ensure that the data is made to remain intact and can, therefore, be re-used in the event that the container shuts down or crashes.

sudo mkdir /var/jenkins
sudo chown -R 1000:1000 /var/jenkins

Step 4: Create a Jenkins Container Systemd service

Create a new systemd service unit file for Jenkins.

sudo vim /etc/systemd/system/jenkins-docker.service

Add:

[Unit]
Description=Jenkins Server
Documentation=https://jenkins.io/doc/
After=docker.service
Requires=docker.service

[Service]
Type=simple
User=jenkins
Group=jenkins
TimeoutStartSec=0
Restart=on-failure
RestartSec=30s
ExecStartPre=-/usr/bin/docker kill jenkins-server
ExecStartPre=-/usr/bin/docker rm jenkins-server
ExecStartPre=/usr/bin/docker pull jenkins/jenkins:lts
ExecStart=/usr/bin/docker run \
          --name jenkins-server \
          --publish 8080:8080 \
          --publish 50000:50000 \
          --volume /var/jenkins:/var/jenkins_home \
          jenkins/jenkins:lts
SyslogIdentifier=jenkins
ExecStop=/usr/bin/docker stop jenkins-server

[Install]
WantedBy=multi-user.target

Reload systemd and start jenkins service

sudo systemctl daemon-reload
sudo systemctl start jenkins-docker

On checking the status, you should get a running message.

$ sudo systemctl status jenkins-docker
* jenkins-docker.service - Jenkins Server
   Loaded: loaded (/etc/systemd/system/jenkins-docker.service; disabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-10-31 15:32:59 PDT; 6min ago
     Docs: https://jenkins.io/doc/
 Main PID: 24964 (docker)
    Tasks: 11 (limit: 1111)
   CGroup: /system.slice/jenkins-docker.service
           `-24964 /usr/bin/docker run --privileged --name jenkins-server --publish 80:8080 --publish 50000:50000 --volume /var/jenkins:/var/jenkins_h

Oct 31 15:33:23 ubuntu-01 jenkins[24964]: INFO: Obtained the updated data file for hudson.tasks.Maven.MavenInstaller
Oct 31 15:33:23 ubuntu-01 jenkins[24964]: Oct 31, 2018 10:33:23 PM hudson.model.AsyncPeriodicWork$1 run
Oct 31 15:33:23 ubuntu-01 jenkins[24964]: INFO: Finished Download metadata. 13,352 ms
Oct 31 15:33:25 ubuntu-01 jenkins[24964]: Oct 31, 2018 10:33:25 PM hudson.model.UpdateSite updateData
Oct 31 15:33:25 ubuntu-01 jenkins[24964]: INFO: Obtained the latest update center data file for UpdateSource default
Oct 31 15:33:25 ubuntu-01 jenkins[24964]: Oct 31, 2018 10:33:25 PM jenkins.InitReactorRunner$1 onAttained
Oct 31 15:33:25 ubuntu-01 jenkins[24964]: INFO: Completed initialization
Oct 31 15:33:25 ubuntu-01 jenkins[24964]: Oct 31, 2018 10:33:25 PM hudson.WebAppMain$3 run
Oct 31 15:33:25 ubuntu-01 jenkins[24964]: INFO: Jenkins is fully up and running

Step 5: Unlocking Jenkins

Browse to the URL http://[serverip|hostname]:8080 to access web installation wizard.

When you first access a new Jenkins instance, you are asked to unlock it using an automatically generated password.

Get the password from

# cat /var/jenkins/secrets/initialAdminPassword 
eec851b6f1ff43ce9f374a5e50d82fad

Copy-paste the automatically-generated alphanumeric password into the Administrator password field and click Continue.

In the next page, install recommended plugins or plugins that suit your desired Jenkins usage. if not sure, select installation of recommended plugins.

Next is to create an admin user account used to manage the Jenkins server.

After a successful installation, you’ll get to Jenkins Management console.

Enjoy automating your jobs with Jenkins. For more reading, check Official Documentation.