`rust+CARGO` not able to specify run options

[greaka]

I don't know if this is possible in current Earthly.

Both the rust+CARGO command and the rust+RUN_WITH_CACHE command do not support --ssh or --mount=type=secret.

This makes it impossible to authenticate against and use private registries.

[idelvall]

We've recently introduced a new function that gives more flexibility, and let's you mount the cargo caches in your own RUN commands: https://github.com/earthly/lib/tree/main/rust#set_cache_mounts_env
This should help you with both cases.