Use 'cfg=target' for pusher binary

[anguslees]

In container_push rule, _pusher executable is copied into the output
runfiles, but not directly invoked by the container_push rule. This
binary could potentially be cross-compiled by other remote executors,
and should use the 'target' config in this action.

[uhthomas]

Maybe I'm misunderstanding but shouldn't this be exec?

[anguslees]

Maybe I'm misunderstanding but shouldn't this be exec?

It's very possible that I'm misunderstanding too - so please double-check 😅

As an executable rule, I think the container_push rule expands a template to produce a shell script - which is usually later executed locally by bazel run. This template/shell script references the _pusher executable, but does not actually execute (ctx.actions.run) _pusher itself - unlike _digester, for comparison.

This means that (hypothetically), the container_push rule can run on one executor, and the _pusher binary can be built on another executor. The only thing that is important, is that the _pusher binary (and runfiles) works on the target platform of the container_push rule.

[uhthomas]

Wow.

[uhthomas]

Thank you :)