docker-build-push/TROUBLESHOOTING.md

# Troubleshooting

* [Cannot push to a registry](#cannot-push-to-a-registry)

## Cannot push to a registry

While pushing to a registry, you may encounter these kinds of issues:

* `failed commit on ref "layer-sha256:...": invalid content digest in response: invalid checksum digest format`
* `failed commit on ref "layer-sha256:...": no response`
* `failed commit on ref "manifest-sha256:...": unexpected status: 400 Bad Request`
* `failed commit on ref "manifest-sha256:...": unexpected status: 401 Unauthorized`
* `unexpected response: 401 Unauthorized`

These issues are not directly related to this action but are rather linked to [buildx](https://github.com/docker/buildx),
[buildkit](https://github.com/moby/buildkit), [containerd](https://github.com/containerd/containerd) or the registry
on which you're pushing your image. The quality of error message depends on the registry and are usually not very informative.

To help you solve this, you should first enable debugging in the
[setup-buildx action step](https://github.com/docker/setup-buildx-action):

```yaml
  -
    name: Set up Docker Buildx
    uses: docker/setup-buildx-action@v1
    with:
      buildkitd-flags: --debug
```

Next you can test pushing with [containerd action](https://github.com/crazy-max/ghaction-setup-containerd) using the
following workflow. If it works then open an issue on [buildkit](https://github.com/moby/buildkit) repository.

```yaml
name: containerd

on:
  push:

jobs:
  containerd:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
        with:
          buildkitd-flags: --debug
      -
        name: Set up containerd
        uses: crazy-max/ghaction-setup-containerd@v1
      -
        name: Build Docker image
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/ppc64le,linux/s390x
          tags: docker.io/user/app:latest
          outputs: type=oci,dest=/tmp/image.tar
      -
        name: Import image in containerd
        run: |
          sudo ctr i import --base-name docker.io/user/app --digests --all-platforms /tmp/image.tar
      -
        name: Push image with containerd
        run: |
          sudo ctr --debug i push --user "${{ secrets.DOCKER_USERNAME }}:${{ secrets.DOCKER_PASSWORD }}" docker.io/user/app:latest
```