Docker backend

This is the original backend used with Woodpecker. The docker backend executes each step inside a separate container started on the agent.

Docker credentials

Woodpecker supports Docker credentials to securely store registry credentials. Install your corresponding credential helper and configure it in your Docker config file passed via WOODPECKER_DOCKER_CONFIG.

To add your credential helper to the Woodpecker server container you could use the following code to build a custom image:

FROM woodpeckerci/woodpecker-server:latest-alpine

RUN apk add -U --no-cache docker-credential-ecr-login

Image cleanup

The agent will not automatically remove images from the host. This task should be managed by the host system. For example, you can use a cron job to periodically do clean-up tasks for the CI runner.

danger

The following commands are destructive and irreversible it is highly recommended that you test these commands on your system before running them in production via a cron job or other automation.

Remove all unused images

docker image rm $(docker images --filter "dangling=true" -q --no-trunc)

Remove Woodpecker volumes

docker volume rm $(docker volume ls --filter name=^wp_* --filter dangling=true  -q)

Tips and tricks

Podman

There is no official support for Podman, but one can try to set the environment variable DOCKER_HOST to point to the Podman socket. It might work. See also the Blog posts.

Configuration

WOODPECKER_BACKEND_DOCKER_NETWORK

Default: empty

Set to the name of an existing network which will be attached to all your pipeline containers (steps). Please be careful as this allows the containers of different pipelines to access each other!

WOODPECKER_BACKEND_DOCKER_ENABLE_IPV6

Default: false

Enable IPv6 for the networks used by pipeline containers (steps). Make sure you configured your docker daemon to support IPv6.

WOODPECKER_BACKEND_DOCKER_VOLUMES

Default: empty

List of default volumes separated by comma to be mounted to all pipeline containers (steps). For example to use custom CA certificates installed on host and host timezone use /etc/ssl/certs:/etc/ssl/certs:ro,/etc/timezone:/etc/timezone.

WOODPECKER_BACKEND_DOCKER_LIMIT_MEM_SWAP

Default: 0

The maximum amount of memory a single pipeline container is allowed to swap to disk, configured in bytes. There is no limit if 0.

WOODPECKER_BACKEND_DOCKER_LIMIT_MEM

Default: 0

The maximum amount of memory a single pipeline container can use, configured in bytes. There is no limit if 0.

WOODPECKER_BACKEND_DOCKER_LIMIT_SHM_SIZE

Default: 0

The maximum amount of memory of /dev/shm allowed in bytes. There is no limit if 0.

WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_QUOTA

Default: 0

The number of microseconds per CPU period that the container is limited to before throttled. There is no limit if 0.

WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_SHARES

Default: 0

The relative weight vs. other containers.

WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_SET

Default: empty

Comma-separated list to limit the specific CPUs or cores a pipeline container can use.

Example: WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_SET=1,2