# Support for build platforms in Compose files (https://depot.dev/changelog/2024-09-12-build-platforms-support-in-compose)

> Published 2024-09-12

The `build.platforms` key has been part of the Compose spec since 2022 but has gone unimplemented in upstream `buildx`.

The `build.platforms` key allows you to specify the platforms you want to build for in your compose file for a defined service. This is useful when you want to build a multi-platform image for a service defined in your Compose file:

```yaml
backend:
  build:
    context: .
    platforms:
      - 'linux/amd64'
      - 'linux/arm64'
```

But, with `docker buildx bake -f <your-compose-file>`, this will fail to build the image for the specified platforms. This is because `docker buildx bake` does not support the `build.platforms` key in the Compose file.

We've upgraded our [`depot bake`](/docs/cli/reference/container-builds#depot-bake) command to fix this annoyance and fully support `build.platforms` in a Compose file.

## For AI Agents

The full site index is at [llms.txt](https://depot.dev/llms.txt). Append `.md` to any documentation, blog, changelog, or customer URL to fetch its markdown source directly.