Nicklas Wiegandt

Using Docker in jenkins with jenkins Docker agent

Getting Jenkins CI to build Docker container with a jenkins Docker agent

The problem

Running Jenkins CI agents as containers is a nice thing. However it can be a hassle if you want to build a container inside the containerized docker agent. Using the standard Jenkins agent container will result in an error telling you that the Docker binary is not found.

The solution

The default Jenkins agent container doesn’t contain the Docker binaries. 😔

Unfortunately the image is missing any description and finding any documentation is hard. You can neither view the Dockerfile nor is the source linked. But in the GitHub repository for the JNLP Agents is a subdirectory called docker in which you can find this Dockerfile. This seems to be the source for the linked image. One can see that the Docker binary is getting installed on build time.

In order to use the agent go to your Jenkins server settings and click on Manage Nodes and CloudsConfigure Clouds.

If you haven’t already set your Docker settings:
Name: docker
Docker Host URI: unix:///var/run/docker.sock

The Jenkins Docker settings
The Jenkins Docker setting

Then open the Docker Agent templates section.
Change the Docker Image to: jenkins/jnlp-agent-docker

The Jenkins agent template settings
The Jenkins agent template settings

After that open the container settings and set the following:
User: root
Volumes: /var/run/docker.sock:/var/run/docker.sock

The Jenkins agent template container settings
The Jenkins agent template container settings

Thats it. Happy dockerizing 🙂