Docker
This is the original backend used with Woodpecker. The docker backend executes each step inside a separate container started on the agent.
Private registries
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
Step specific configuration
Run user
By default the docker backend starts the step container without the --user
flag. This means the step container will use the default user of the container. To change this behavior you can set the user
backend option to the preferred user/group:
steps:
- name: example
image: alpine
commands:
- whoami
backend_options:
docker:
user: 65534:65534
The syntax is the same as the docker run --user
flag.
Tips and tricks
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.
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)
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.
Environment variables
BACKEND_DOCKER_NETWORK
- Name:
WOODPECKER_BACKEND_DOCKER_NETWORK
- Default: none
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!
BACKEND_DOCKER_ENABLE_IPV6
- Name:
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.
BACKEND_DOCKER_VOLUMES
- Name:
WOODPECKER_BACKEND_DOCKER_VOLUMES
- Default: none
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
.
BACKEND_DOCKER_LIMIT_MEM_SWAP
- Name:
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
.
BACKEND_DOCKER_LIMIT_MEM
- Name:
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
.
BACKEND_DOCKER_LIMIT_SHM_SIZE
- Name:
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
.
BACKEND_DOCKER_LIMIT_CPU_QUOTA
- Name:
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
.
BACKEND_DOCKER_LIMIT_CPU_SHARES
- Name:
WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_SHARES
- Default:
0
The relative weight vs. other containers.
BACKEND_DOCKER_LIMIT_CPU_SET
- Name:
WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_SET
- Default: none
Comma-separated list to limit the specific CPUs or cores a pipeline container can use.
Example: WOODPECKER_BACKEND_DOCKER_LIMIT_CPU_SET=1,2