Official Jenkins Docker image
The Jenkins Continuous Integration and Delivery server.
This is a fully functional Jenkins server. http://jenkins.io/.
Azure Fork Notes
Some changes have been made to the default offical Dockerfile:
- SSH is installed (OpenSSH), and configured to run on port 2222. The password set as expected by Azure Web App For Containers (root/Docker!)
- Port 2222 exposed
- Jenkins runs as root, this is a workaround for an issue with Azure Container Instance, where ACI mounts volumes as UID 0 root stopping Jenkins from starting. This is an example template for running this image
JENKINS_HOMEmoved to /home/jenkins this has been done so when running in Azure Web App For Containers, data can be persisted. Note. You must change app setting
WEBSITES_ENABLE_APP_SERVICE_STORAGEto true in order for the /home directory to be mounted, this defaults to false.
When running in Azure Web App For Containers, to access your container via SSH use the Kudu web console or the following URL
docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts
NOTE: read below the build executors part 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
this will automatically create a 'jenkins_home' volume on docker host, that will survive container stop/restart/deletion.
Avoid using a bind mount from a folder on host into
/var/jenkins_home, as this might result in file permission issue. If you really need to bind mount jenkins_home, ensure that directory on host is accessible by the jenkins user in container (jenkins user - uid 1000) or use
-u some_other_user parameter with
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 Managing data in containers
Setting the number of executors
You can specify and set the number of executors of your Jenkins master instance using a groovy script. By default its set to 2 executors, but you can extend the image and change it to your desired number of executors :
import jenkins.model.* Jenkins.instance.setNumExecutors(5)
FROM jenkins/jenkins:lts COPY executors.groovy /usr/share/jenkins/ref/init.groovy.d/executors.groovy
Attaching build executors
You can run builds on the master out of the box.
But if you want to attach build slave servers through JNLP (Java Web Start): make sure you map the port:
-p 50000:50000 - which will be used when you connect a slave agent.
If you are only using SSH slaves, then you do NOT need to put that port mapping.
Passing JVM parameters
You might need to customize the JVM running Jenkins, typically to pass system properties or tweak heap memory settings. Use 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
Jenkins logging can be configured through a properties file and
java.util.logging.config.file Java property.
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
Configuring reverse proxy
If you want to install Jenkins behind a reverse proxy with prefix, example: mysite.com/jenkins, you need to add environnement 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:
Passing Jenkins launcher parameters
Argument you pass to docker running the jenkins image are passed to jenkins launcher, so you can run for sample :
docker run jenkins/jenkins:lts --version
This will dump Jenkins version, just like when you run jenkins as an executable war.
You also can define jenkins arguments as
JENKINS_OPTS. This is usefull to define a set of arguments to pass to jenkins launcher as you
define a derived jenkins image based on the official one with some customized settings. The following sample Dockerfile uses this option
to force use of HTTPS with a certificate included in the image
FROM jenkins/jenkins:lts COPY https.pem /var/lib/jenkins/cert COPY 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 slave agent port for jenkins by defining
JENKINS_SLAVE_AGENT_PORT in a sample Dockerfile.
FROM jenkins/jenkins:lts 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
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 # 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 COPY custom.groovy /usr/share/jenkins/ref/init.groovy.d/custom.groovy
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, an 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
It is possible to override the environment variables in images.
:exclamation: Note that changing this variables will not change the Update Center being used by Jenkins runtime.
Plugin version format
Use plugin artifact ID, without
-plugin extension, and append the version if needed separated by
Dependencies that are already included in the Jenkins war will only be downloaded if their required version is newer than the one included.
There are also custom version specifiers:
latest- download the latest version from the main update center.
For Jenkins LTS images
experimental- download the latest version from the experimental update center defined by the
JENKINS_UC_EXPERIMENTALenvironment variable (example:
You can run the script manually in Dockerfile:
FROM jenkins/jenkins:lts RUN /usr/local/bin/install-plugins.sh docker-slaves github-branch-source:1.8
Furthermore it is possible to pass a file that contains this set of plugins (with or without line breaks).
FROM jenkins/jenkins:lts COPY plugins.txt /usr/share/jenkins/ref/plugins.txt RUN /usr/local/bin/install-plugins.sh < /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:firstname.lastname@example.org: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/ /:/'
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.
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!
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.
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.
Build with the usual
docker build -t jenkins/jenkins .
Tests are written using bats under the
Bats can be easily installed with
brew install bats on OS X
Jump on irc.freenode.net and the #jenkins room. Ask!