README.md

cargo-out-dir

Build a package and output its build script's OUT_DIR, the directory where build.rs writes generated files. Use it when a later step needs those files; for a sealed build use cargo-docker with out-dir-package, which translates the path to the host.

Usage

- uses: gronke/ci/.github/actions/rust/cargo-out-dir@v3
  id: out
  with:
    package: my-crate      # optional in a single-package workspace
    profile: release       # optional; empty is dev
    args: "--locked"       # optional
- run: ls "${{ steps.out.outputs.out-dir }}"

Inputs

Input	Default	Description
package	""	Package whose build script to resolve (cargo build -p). Empty resolves the workspace's sole or root package via cargo pkgid; a larger workspace needs the name.
working-directory	.	Directory to run cargo in.
profile	""	Cargo profile (--profile), e.g. release. Empty is dev.
args	""	Extra cargo build args.

Outputs

Output	Description
out-dir	Absolute path of the resolved build script's OUT_DIR.

Notes

• Needs jq on the runner; the action reads cargo's JSON message stream with it.
• The action is the build step: it runs cargo build --message-format=json-diagnostic-rendered-ansi and selects the build-script-executed message whose package_id equals the cargo pkgid output exactly.
• A different profile or feature set builds into a different OUT_DIR, so pass the same profile and args as the build that consumes the output rather than resolving after a differently configured build.
• Zero matches (no build.rs, or a cargo older than 1.77 whose package ids do not match cargo pkgid) or more than one distinct directory fail the step.
• Compiler diagnostics are replayed to the log after the build, so warnings and errors stay readable despite the JSON stream.