CircleCI Runner Installation with Docker

Additional prerequisites

The host needs to have Docker installed. Once the runner container is started, the container will immediately attempt to start running jobs. The container will be reused to run more jobs indefinitely until it is stopped.

The number of containers running in parallel on the host is constrained by the host’s available resources and your jobs' performance requirements.

Create a Dockerfile that extends the CircleCI runner image

In this example, Python 3 is installed on top of the base image.

Dockerfile.runner.extended

FROM circleci/runner:launch-agent
RUN sudo apt-get update; \
    sudo apt-get install --no-install-recommends -y \
        python3

Build the Docker image

docker build --file ./Dockerfile.runner.extended .

Start the Docker container

The environment variable values are not available to the docker command, so these environment variables are not visible in ps output.
CIRCLECI_RESOURCE_CLASS=<resource-class> CIRCLECI_API_TOKEN=<runner-token> docker run --env CIRCLECI_API_TOKEN --env CIRCLECI_RESOURCE_CLASS --name <container-name> <image-id-from-previous-step>

When the container starts, it will immediately attempt to start running jobs.

Start the Docker container on server

When starting the docker container on server, the agent_version environment variable will need to be passed in using the --env flag.

CIRCLECI_RESOURCE_CLASS=<resource-class> CIRCLECI_API_TOKEN=<runner-token> agent_version=<agent_version_for_server> docker run --env agent_version --env CIRCLECI_API_TOKEN --env CIRCLECI_RESOURCE_CLASS --name <container-name> <image-id-from-previous-step>

Stopping the Docker container

docker stop <container-name>

Remove the Docker container

In some cases you might need to fully remove a stopped runner container from the system, such as when recreating a container using the same name.

docker stop <container-name>; docker rm <container-name>;


Help make this document better

This guide, as well as the rest of our docs, are open-source and available on GitHub. We welcome your contributions.