Jenkins auto slave

A docker image of Jenkins JNLP based agent. This image can self-register to Jenkins master, it will also unregister from the master when container exits. Another cool feature is that this image doesn't have agent.jar pre installed, instead it downloads it from Jenkins master when the container starts. This approach will help to avoid versioning problems that might happen between master and slave.

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Environment variables

most used variables:

• JENKINS_AUTH jenkins server username and either password or API token (in user:secet format)
• JENKINS_URL jenkins master url (example http://localhost:8080)
• JENKINS_SLAVE_LABEL space delimited labels, used to group agents into one logical group (no default)
• JENKINS_SLAVE_MODE how Jenkins schedules builds on this node, NORMAL/EXCLUSIVE (default is NORMAL)
• JENKINS_SLAVE_NAME the name which will be used when registering (default is $HOSTNAME)
• JENKINS_SLAVE_NUM_EXECUTORS number of executors to use (defaults to 1)

less used and can keep the defaults

• DOCKER_GROUP the docker group name, should be same as the docker's host group (defaults to docker)
• DOCKER_SOCKET the docker socket location (default is /var/run/docker.sock)
• JAVA_OPTS pass java options to the slave.jar process (default is not set)

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Required permissions

The image should be used in trusted environment, even so the permissions for the user that will be used to register the slaves should be restricted.

DO NOT USE ADMIN USER

Therefore, in order to be able to self register to the master, a user with relevant permissions must be created.

The required permissions are:

• Overall/Read
• Agent/Connect
• Agent/Create
• Agent/Delete

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Running

when running without any env variables:

$ docker run --rm simenduev/jenkins-auto-slave
please set both JENKINS_URL and JENKINS_AUTH env. variables
example:
JENKINS_AUTH=user:password
JENKINS_URL=http://localhost:8080

the basic working command:

$ docker run -d \
    --net host \
    -e JENKINS_URL=http://jenkins.internal.domain:8080 \
    -e JENKINS_AUTH=registrator:1234567890123456789012  \
    -v /any/path/you/like:/var/jenkins_home \
    simenduev/jenkins-auto-slave

Mounting of /var/jenkins_home volume is required in order for agent to be able to build jobs.

below command will also permit the slave run docker commands:

$ docker run -d \
    --net host \
    -e JENKINS_URL=http://jenkins.internal.domain:8080 \
    -e JENKINS_AUTH=registrator:1234567890123456789012  \
    -v /any/path/you/like:/var/jenkins_home \
    -v /run/docker.sock:/run/docker.sock \
    -v /usr/bin/docker:/usr/bin/docker \
    simenduev/jenkins-auto-slave

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