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Troubleshooting Dagger

This page describes problems you may encounter when using Dagger, and their solutions.

Dagger pipeline is unresponsive with a BuildKit error​

A Dagger pipeline may hang or become unresponsive, eventually generating a BuildKit error such as buildkit failed to respond or container state improper.

To resolve this error, you must stop and remove the Dagger Engine container and (optionally) clear the container state.

  1. Stop and remove the Dagger Engine container:

    DAGGER_ENGINE_DOCKER_CONTAINER="$(docker container list --all --filter 'name=^dagger-engine-*' --format '{{.Names}}')"
    docker container stop "$DAGGER_ENGINE_DOCKER_CONTAINER"
    docker container rm "$DAGGER_ENGINE_DOCKER_CONTAINER"

  2. Clear unused volumes and data:

    info

    This step is optional. It will remove the cache and result in a slow first run when the container is re-provisioned.

    docker volume prune
    docker system prune

You should now be able to re-run your Dagger pipeline successfully.

tip

If you have custom-provisioned the Dagger Engine, please adjust the above commands to your environment.

Dagger pipeline is unable to resolve host names after network configuration changes​

If the network configuration of the host changes after the Dagger Engine container starts, Docker does not notify the Dagger Engine of the change. This may cause Dagger pipelines to fail with network-related errors.

As an example, if the nameserver configuration of the host changes after switching to a different network connection or connecting/disconnecting a VPN result, the Dagger pipeline may fail with DNS resolution errors.

To resolve this error, you must restart the Dagger Engine container after the host network configuration changes.

DAGGER_ENGINE_DOCKER_CONTAINER="$(docker container list --all --filter 'name=^dagger-engine-*' --format '{{.Names}}')"
docker restart "$DAGGER_ENGINE_DOCKER_CONTAINER"

You should now be able to re-run your Dagger pipeline successfully.