build: note about sunset of gha cache v1 (#22395)

## Description

Note about sunset of GitHub Cache service v1 on April 15th, 2025.

## Related issues or tickets

* https://gh.io/gha-cache-sunset
* docker/build-push-action#1345
* docker/setup-buildx-action#414
* moby/buildkit#5896
*
actions/runner-images#11766 (comment)

## Reviews

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<!-- List applicable reviews (optionally @tag reviewers) -->

- [x] Technical review
- [x] Editorial review
- [ ] Product review

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

content/manuals/build/ci/github-actions/cache.md

@@ -87,9 +87,9 @@ jobs:
 {{< summary-bar feature_name="Cache backend API" >}}
 
 The [GitHub Actions cache exporter](../../cache/backends/gha.md)
-backend uses the [GitHub Cache API](https://github.com/tonistiigi/go-actions-cache/blob/master/api.md)
+backend uses the [GitHub Cache service API](https://github.com/tonistiigi/go-actions-cache)
 to fetch and upload cache blobs. That's why you should only use this cache
-backend in a GitHub Action workflow, as the `url` (`$ACTIONS_CACHE_URL`) and
+backend in a GitHub Action workflow, as the `url` (`$ACTIONS_RESULTS_URL`) and
 `token` (`$ACTIONS_RUNTIME_TOKEN`) attributes only get populated in a workflow
 context.
 
@@ -121,6 +121,64 @@ jobs:
           cache-to: type=gha,mode=max
 ```
 
+> [!IMPORTANT]
+>
+> Starting [April 15th, 2025, only GitHub Cache service API v2 will be supported](https://gh.io/gha-cache-sunset).
+> 
+> If you encounter the following error during your build:
+> 
+> ```console
+> ERROR: failed to solve: This legacy service is shutting down, effective April 15, 2025. Migrate to the new service ASAP. For more information: https://gh.io/gha-cache-sunset
+> ```
+> 
+> You're probably using outdated tools that only support the legacy GitHub
+> Cache service API v1. Here are the minimum versions you need to upgrade to
+> depending on your use case:
+> * Docker Buildx >= v0.21.0
+> * BuildKit >= v0.20.0
+> * Docker Compose >= v2.33.1
+> * Docker Engine >= v28.0.0 (if you're building using the Docker driver with containerd image store enabled)
+> 
+> If you're building using the `docker/build-push-action` or `docker/bake-action`
+> actions on GitHub hosted runners, Docker Buildx and BuildKit are already up
+> to date but on self-hosted runners, you may need to update them yourself.
+> Alternatively, you can use the `docker/setup-buildx-action` action to install
+> the latest version of Docker Buildx:
+> 
+> ```yaml
+> - name: Set up Docker Buildx
+>   uses: docker/setup-buildx-action@v3
+>   with:
+>    version: latest
+> ```
+> 
+> If you're building using Docker Compose, you can use the
+> `docker/setup-compose-action` action:
+> 
+> ```yaml
+> - name: Set up Docker Compose
+>   uses: docker/setup-compose-action@v1
+>   with:
+>    version: latest
+> ```
+> 
+> If you're building using the Docker Engine with the containerd image store
+> enabled, you can use the `docker/setup-docker-action` action:
+> 
+> ```yaml
+> -
+>   name: Set up Docker
+>   uses: docker/setup-docker-action@v4
+>   with:
+>     version: latest
+>     daemon-config: |
+>       {
+>         "features": {
+>           "containerd-snapshotter": true
+>         }
+>       }
+> ```
+
 ### Cache mounts
 
 BuildKit doesn't preserve cache mounts in the GitHub Actions cache by default.