Description

Motivation

Currently, buildx doesn't provide granular exit codes that correspond to specific error types from buildkit. This makes it difficult to programmatically determine the exact nature of a failure, especially in CI/CD environments where automatic retry or fallback logic might depend on the specific type of error.

Proposal

Expand the buildx exit code system to map buildkit's error classifications to unique exit codes. As an initial implementation, focus on the "internal" errors defined in the moby/buildkit errdef package.

Follow-on work

• Expand codes to cover additional error categories/cases
  - GHA handling