doytsujin / docker-3

Docker official jenkins repo

Official Jenkins Docker image

The Jenkins Continuous Integration and Delivery server available on Docker Hub.

This is a fully functional Jenkins server. https://jenkins.io/.

Usage

docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts-jdk11

NOTE: read the section Connecting agents below for the role of the 50000 port mapping.

This will store the workspace in /var/jenkins_home. All Jenkins data lives in there - including plugins and configuration. You will probably want to make that an explicit volume so you can manage it and attach to another container for upgrades :

docker run -p 8080:8080 -p 50000:50000 -v jenkins_home:/var/jenkins_home jenkins/jenkins:lts-jdk11

This will automatically create a 'jenkins_home' docker volume on the host machine. Docker volumes retain their content even when the container is stopped, started, or deleted.

NOTE: Avoid using a bind mount from a folder on the host machine into /var/jenkins_home, as this might result in file permission issues (the user used inside the container might not have rights to the folder on the host machine). If you really need to bind mount jenkins_home, ensure that the directory on the host is accessible by the jenkins user inside the container (jenkins user - uid 1000) or use -u some_other_user parameter with docker run.

docker run -d -v jenkins_home:/var/jenkins_home -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts-jdk11

this will run Jenkins in detached mode with port forwarding and volume added. You can access logs with command 'docker logs CONTAINER_ID' in order to check first login token. ID of container will be returned from output of command above.

Backing up data

If you bind mount in a volume - you can simply back up that directory (which is jenkins_home) at any time.

This is highly recommended. Treat the jenkins_home directory as you would a database - in Docker you would generally put a database on a volume.

If your volume is inside a container - you can use docker cp $ID:/var/jenkins_home command to extract the data, or other options to find where the volume data is. Note that some symlinks on some OSes may be converted to copies (this can confuse jenkins with lastStableBuild links etc)

For more info check Docker docs section on Use volumes

Setting the number of executors

You can define the number of executors on the Jenkins built-in node using a groovy script. By default it is set to 2 executors, but you can extend the image and change it to your desired number of executors (recommended 0 executors on the built-in node) :

executors.groovy

import jenkins.model.*
Jenkins.instance.setNumExecutors(0) // Recommended to not run builds on the built-in node

and Dockerfile

FROM jenkins/jenkins:lts
COPY --chown=jenkins:jenkins executors.groovy /usr/share/jenkins/ref/init.groovy.d/executors.groovy

Connecting agents

You can run builds on the controller out of the box. The Jenkins project recommends that no executors be enabled on the controller.

In order to connect agents through an inbound TCP connection, map the port: -p 50000:50000. That port will be used when you connect agents to the controller.

If you are only using SSH (outbound) build agents, this port is not required, as connections are established from the controller. If you connect agents using web sockets (since Jenkins 2.217), the TCP agent port is not used either.

Passing JVM parameters

You might need to customize the JVM running Jenkins, typically to adjust system properties or tweak heap memory settings. Use the JAVA_OPTS environment variable for this purpose :

docker run --name myjenkins -p 8080:8080 -p 50000:50000 --env JAVA_OPTS=-Dhudson.footerURL=http://mycompany.com jenkins/jenkins:lts-jdk11

Configuring logging

Jenkins logging can be configured through a properties file and java.util.logging.config.file Java property. For example:

mkdir data
cat > data/log.properties <<EOF
handlers=java.util.logging.ConsoleHandler
jenkins.level=FINEST
java.util.logging.ConsoleHandler.level=FINEST
EOF
docker run --name myjenkins -p 8080:8080 -p 50000:50000 --env JAVA_OPTS="-Djava.util.logging.config.file=/var/jenkins_home/log.properties" -v `pwd`/data:/var/jenkins_home jenkins/jenkins:lts-jdk11

Configuring reverse proxy

If you want to install Jenkins behind a reverse proxy with prefix, example: mysite.com/jenkins, you need to add environment variable JENKINS_OPTS="--prefix=/jenkins" and then follow the below procedures to configure your reverse proxy, which will depend if you have Apache or Nginx:

• Apache
• Nginx

Passing Jenkins launcher parameters

Arguments you pass to docker running the Jenkins image are passed to jenkins launcher, so for example you can run:

docker run jenkins/jenkins:lts-jdk11 --version

This will show the Jenkins version, the same as when you run Jenkins from an executable war.

You can also define Jenkins arguments via JENKINS_OPTS. This is useful for customizing arguments to the jenkins launcher in a derived Jenkins image. The following sample Dockerfile uses this option to force use of HTTPS with a certificate included in the image.

FROM jenkins/jenkins:lts-jdk11

COPY --chown=jenkins:jenkins https.pem /var/lib/jenkins/cert
COPY --chown=jenkins:jenkins https.key /var/lib/jenkins/pk
ENV JENKINS_OPTS --httpPort=-1 --httpsPort=8083 --httpsCertificate=/var/lib/jenkins/cert --httpsPrivateKey=/var/lib/jenkins/pk
EXPOSE 8083

You can also change the default agent port for Jenkins by defining JENKINS_SLAVE_AGENT_PORT in a sample Dockerfile.

FROM jenkins/jenkins:lts-jdk11
ENV JENKINS_SLAVE_AGENT_PORT 50001

or as a parameter to docker,

docker run --name myjenkins -p 8080:8080 -p 50001:50001 --env JENKINS_SLAVE_AGENT_PORT=50001 jenkins/jenkins:lts-jdk11

Note: This environment variable will be used to set the port adding the [system property][https://www.jenkins.io/doc/book/managing/system-properties/] jenkins.model.Jenkins.slaveAgentPort to JAVA_OPTS.

If this property is already set in JAVA_OPTS, then the value of JENKINS_SLAVE_AGENT_PORT will be ignored.

Installing more tools

You can run your container as root - and install via apt-get, install as part of build steps via jenkins tool installers, or you can create your own Dockerfile to customise, for example:

FROM jenkins/jenkins:lts-jdk11
# if we want to install via apt
USER root
RUN apt-get update && apt-get install -y ruby make more-thing-here
# drop back to the regular jenkins user - good practice
USER jenkins

In such a derived image, you can customize your jenkins instance with hook scripts or additional plugins. For this purpose, use /usr/share/jenkins/ref as a place to define the default JENKINS_HOME content you wish the target installation to look like :

FROM jenkins/jenkins:lts-jdk11
COPY --chown=jenkins:jenkins custom.groovy /usr/share/jenkins/ref/init.groovy.d/custom.groovy

Preinstalling plugins

Install plugins script

You can rely on the install-plugins.sh script to pass a set of plugins to download with their dependencies. This script will perform downloads from update centers, and internet access is required for the default update centers.

Setting update centers

During the download, the script will use update centers defined by the following environment variables:

• JENKINS_UC - Main update center. This update center may offer plugin versions depending on the Jenkins LTS Core versions. Default value: https://updates.jenkins.io
• JENKINS_UC_EXPERIMENTAL - Experimental Update Center. This center offers Alpha and Beta versions of plugins. Default value: https://updates.jenkins.io/experimental
• JENKINS_INCREMENTALS_REPO_MIRROR - Defines Maven mirror to be used to download plugins from the Incrementals repo. Default value: https://repo.jenkins-ci.org/incrementals
• JENKINS_UC_DOWNLOAD - Download url of the Update Center. Default value: $JENKINS_UC/download

It is possible to override the environment variables in images.

❗ Note that changing update center variables will not change the Update Center being used by Jenkins runtime.

Plugin installation manager CLI (Preview)

You can also use the jenkins-plugin-cli tool to install plugins. This CLI will perform downloads from update centers, and internet access is required for the default update centers.

See the CLI's documentation for more information, or run jenkins-plugin-cli --help to see the available options.

Installing Custom Plugins

Installing prebuilt, custom plugins can be accomplished by copying the plugin HPI file into /usr/share/jenkins/ref/plugins/ within the Dockerfile:

COPY --chown=jenkins:jenkins path/to/custom.hpi /usr/share/jenkins/ref/plugins/

Usage

You can run the CLI manually in Dockerfile:

Plugin installation manager CLI

FROM jenkins/jenkins:lts-jdk11
RUN jenkins-plugin-cli --plugins pipeline-model-definition github-branch-source:1.8

Furthermore it is possible to pass a file that contains this set of plugins (with or without line breaks).

install-plugins script (Deprecated)

FROM jenkins/jenkins:lts-jdk11
RUN /usr/local/bin/install-plugins.sh pipeline-model-definition github-branch-source:1.8

install-plugins script

FROM jenkins/jenkins:lts-jdk11
COPY --chown=jenkins:jenkins plugins.txt /usr/share/jenkins/ref/plugins.txt
RUN /usr/local/bin/install-plugins.sh < /usr/share/jenkins/ref/plugins.txt

Plugin installation manager CLI (Preview)

FROM jenkins/jenkins:lts-jdk11
COPY --chown=jenkins:jenkins plugins.txt /usr/share/jenkins/ref/plugins.txt
RUN jenkins-plugin-cli -f /usr/share/jenkins/ref/plugins.txt

When jenkins container starts, it will check JENKINS_HOME has this reference content, and copy them there if required. It will not override such files, so if you upgraded some plugins from UI they won't be reverted on next start.

In case you do want to override, append '.override' to the name of the reference file. E.g. a file named /usr/share/jenkins/ref/config.xml.override will overwrite an existing config.xml file in JENKINS_HOME.

Also see JENKINS-24986

Here is an example to get the list of plugins from an existing server:

JENKINS_HOST=username:[email protected]:port
curl -sSL "http://$JENKINS_HOST/pluginManager/api/xml?depth=1&xpath=/*/*/shortName|/*/*/version&wrapper=plugins" | perl -pe 's/.*?<shortName>([\w-]+).*?<version>([^<]+)()(<\/\w+>)+/\1 \2\n/g'|sed 's/ /:/'

Example Output:

cucumber-testresult-plugin:0.8.2
pam-auth:1.1
matrix-project:1.4.1
script-security:1.13
...

For 2.x-derived images, you may also want to

RUN echo 2.0 > /usr/share/jenkins/ref/jenkins.install.UpgradeWizard.state

to indicate that this Jenkins installation is fully configured. Otherwise a banner will appear prompting the user to install additional plugins, which may be inappropriate.

Updating plugins file (Preview)

The plugin-installation-manager-tool supports updating the plugin file for you.

Example command:

JENKINS_IMAGE=jenkins/jenkins:lts-jdk11
docker run -it ${JENKINS_IMAGE} bash -c "stty -onlcr && jenkins-plugin-cli -f /usr/share/jenkins/ref/plugins.txt --available-updates --output txt" >  plugins2.txt
mv plugins2.txt plugins.txt

Upgrading

All the data needed is in the /var/jenkins_home directory - so depending on how you manage that - depends on how you upgrade. Generally - you can copy it out - and then "docker pull" the image again - and you will have the latest LTS - you can then start up with -v pointing to that data (/var/jenkins_home) and everything will be as you left it.

As always - please ensure that you know how to drive docker - especially volume handling!

Upgrading plugins

By default, plugins will be upgraded if they haven't been upgraded manually and if the version from the docker image is newer than the version in the container. Versions installed by the docker image are tracked through a marker file.

To force upgrades of plugins that have been manually upgraded, run the docker image with -e PLUGINS_FORCE_UPGRADE=true.

The default behaviour when upgrading from a docker image that didn't write marker files is to leave existing plugins in place. If you want to upgrade existing plugins without marker you may run the docker image with -e TRY_UPGRADE_IF_NO_MARKER=true. Then plugins will be upgraded if the version provided by the docker image is newer.

Hacking

If you wish to contribute fixes to this repository, please refer to the dedicated documentation.

Questions?

We're on Gitter, https://gitter.im/jenkinsci/docker