--cache-to with remote builders results in the cache being written in the host and not in the remote builder

[GonzaloSaez]

Contributing guidelines

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I've found a bug and checked that ...

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Description

When using remote builders together with --cache-to directives, the cache ends up being written into the host filesystem and not the remote builder filesystem.

Expected behaviour

The expected behavior is for the cache layers to be written in the remote builder or at least to have an option to do so.

Actual behaviour

The cache layers are written into the host

Buildx version

v0.19.0

Docker info

Builders list

Using a remote builder

Configuration

dockerfile

Build logs

Additional info

No response

[tonistiigi]

I guess you mean --cache-to type=local. This is expected, type=local writes cache to your local filesystem on the client side.