Add --rosetta option for arm64 images

[rgov]

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Motivation and Context

container automatically enables Rosetta for amd64 containers. This change allows Rosetta to be enabled for arm64 containers by passing the --rosetta flag. This allows native containers to benefit from being able to execute the occasional amd64 executable in niche situations, e.g., containers used for cross-compilation.

Resolves #391.

I considered adding a warning for passing --rosetta when it is not necessary, but there wasn't obvious infrastructure for conveying the message.

Testing

• Tested locally
• Added/updated tests
• Added/updated docs

I tested by downloading a statically linked x86 binary and running it inside an arm64 Alpine container created with the new --rosetta flag.

I attempted to write a test case but I hit this issue with my Swift toolchain. An ideal test case might involve actually executing an amd64 binary within an arm64 container, but I didn't come up with a simple way to do so.

[dcantah]

This LGTM (and think it's useful), but some other folks may have differing opinions. Will leave open for one other set of eyes

[flukejones]

Thank you this. It is incredibly helpful for scenarios where I use buildroot and yocto at work.

[dcantah]

Going to check this in. We can always revert if we find an issue or anyone has concerns on the ux.