Add Troubleshooting section

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -3,6 +3,10 @@ name: Bug report
 about: Create a report to help us improve
 ---
 
+### Troubleshooting
+
+Before sumbitting a bug report please read the [Troubleshooting section](https://github.com/docker/build-push-action#troubleshooting) in the README.
+
 ### Behaviour
 
 #### Steps to reproduce this issue

README.md

@@ -30,6 +30,7 @@ ___
 * [Customizing](#customizing)
   * [inputs](#inputs)
   * [outputs](#outputs)
+* [Troubleshooting](#troubleshooting)
 * [Keep up-to-date with GitHub Dependabot](#keep-up-to-date-with-github-dependabot)
 * [Limitation](#limitation)
 
@@ -44,8 +45,8 @@ build-secrets, remote cache, etc. and different builder deployment/namespacing o
 
 The default behavior of this action is to use the [Git context invoked by your workflow](https://github.com/docker/build-push-action/blob/master/src/context.ts#L35).
 
-> :warning: Subdir for this context is [not yet supported](https://github.com/docker/build-push-action/issues/120).
+<details>
-> For the moment you can use the [path context](#path-context).
+  <summary><b>Show workflow</b></summary>
   
   ```yaml
 name: ci
@@ -81,6 +82,7 @@ jobs:
         name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}
   ```
+</details>
 
 If you use this action in a private repository, you have to pass the [GitHub Token](https://help.github.com/en/actions/configuring-and-managing-workflows/authenticating-with-the-github_token)
 as a secret named `GIT_AUTH_TOKEN` to be able to authenticate against it with buildx:
@@ -97,10 +99,16 @@ as a secret named `GIT_AUTH_TOKEN` to be able to authenticate against it with bu
             GIT_AUTH_TOKEN=${{ github.token }}
 ```
 
+> :warning: Subdir for Git context is [not yet supported](https://github.com/docker/build-push-action/issues/120).
+> For the moment you can use the [path context](#path-context).
+
 ### Path context
 
 You can also use the `PATH` context alongside the [`actions/checkout`](https://github.com/actions/checkout/) action.
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -137,9 +145,13 @@ jobs:
             push: true
             tags: user/app:latest
   ```
+</details>
 
 ### Isolated builders
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -176,9 +188,13 @@ jobs:
             builder: ${{ steps.builder2.outputs.name }}
             target: mytarget2
   ```
+</details>
 
 ### Multi-platform image
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -217,6 +233,7 @@ jobs:
               user/app:latest
               user/app:1.0.0
   ```
+</details>
 
 ## Advanced usage
 
@@ -224,6 +241,9 @@ jobs:
 
 For testing purposes you may need to create a [local registry](https://hub.docker.com/_/registry) to push images into.
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -259,12 +279,16 @@ jobs:
           run: |
             docker buildx imagetools inspect localhost:5000/name/app:latest
   ```
+</details>
 
 ### Leverage GitHub cache
 
 You can leverage [GitHub cache](https://docs.github.com/en/actions/configuring-and-managing-workflows/caching-dependencies-to-speed-up-workflows)
 using [actions/cache](https://github.com/actions/cache) with this action.
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -302,6 +326,7 @@ jobs:
             cache-from: type=local,src=/tmp/.buildx-cache
             cache-to: type=local,dest=/tmp/.buildx-cache
   ```
+</details>
 
 ### Complete workflow
 
@@ -322,6 +347,9 @@ might want to use:
 | `push`          | `refs/heads/my/branch`        | `a5df687`  | `sha-a5df687`, `my-branch`         | Yes    |
 | `push tag`      | `refs/tags/v1.2.3`            |            | `v1.2.3`, `v1.2`, `v1`, `latest`   | Yes    |
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -404,6 +432,7 @@ jobs:
               org.opencontainers.image.revision=${{ github.sha }}
               org.opencontainers.image.licenses=${{ github.event.repository.license.spdx_id }}
   ```
+</details>
 
 ### Update DockerHub repo description
 
@@ -411,6 +440,9 @@ You can update the [Docker Hub repository description](https://docs.docker.com/d
 a third-party action called [Docker Hub Description](https://github.com/peter-evans/dockerhub-description)
 with this action.
 
+<details>
+  <summary><b>Show workflow</b></summary>
+  
   ```yaml
   name: ci
 
@@ -448,6 +480,7 @@ jobs:
             DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
             DOCKERHUB_REPOSITORY: user/app
   ```
+</details>
 
 ## Customizing
 
@@ -503,6 +536,34 @@ Following outputs are available
 |---------------|---------|---------------------------------------|
 | `digest`      | String  | Image content-addressable identifier also called a digest |
 
+## Troubleshooting
+
+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: 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 using [this workflow](https://github.com/crazy-max/ghaction-setup-containerd#build-and-push-docker-image).
+Do not forget to set `ctr --debug` for the pushing step. If it works then open an issue on
+[buildkit](https://github.com/moby/buildkit) repository.
+
 ## Keep up-to-date with GitHub Dependabot
 
 Since [Dependabot](https://docs.github.com/en/github/administering-a-repository/keeping-your-actions-up-to-date-with-github-dependabot)