rust: build fails if main.rs relocated to src/main.rs

[jdolitsky]

Running thew action chainguard-dev/actions/melange-build@main:

2022/07/13 22:11:55 melange (hello-server/aarch64): populating workspace /tmp/melange-workspace-833668723 from .
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> .gitignore
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> Cargo.lock
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> Cargo.toml
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> apko.yaml
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> melange.rsa
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> melange.rsa.pub
2022/07/13 22:11:55 melange (hello-server/aarch64):   -> melange.yaml
2022/07/13 22:11:55 melange (hello-server/aarch64): running the main pipeline
2022/07/13 22:11:55 melange (hello-server/aarch64): running step Build Rust application
2022/07/13 22:11:55 melange (hello-server/aarch64):     ${{package.version}}: 0.1.0
2022/07/13 22:11:55 melange (hello-server/aarch64):     ${{package.epoch}}: 0
2022/07/13 22:11:55 melange (hello-server/aarch64):     ${{targets.destdir}}: /home/build/melange-out/hello-server
2022/07/13 22:11:55 melange (hello-server/aarch64):     ${{package.name}}: hello-server
2022/07/13 22:11:56 melange (hello-server/aarch64): error: failed to parse manifest at `/home/build/Cargo.toml`
2022/07/13 22:11:56 melange (hello-server/aarch64): 
2022/07/13 22:11:56 melange (hello-server/aarch64): Caused by:
2022/07/13 22:11:56 melange (hello-server/aarch64):   no targets specified in the manifest
2022/07/13 22:11:56 melange (hello-server/aarch64):   either src/lib.rs, src/main.rs, a [lib] section, or [[bin]] section must be present

For some reason, if moving the file to src/main.rs (more idiomatic for Rust), it does not appear in the workspace

[jdolitsky]

This issue does not occur locally, which makes me think it is related to running the upstream GitHub action (chainguard-dev/actions/melange-build@main)

[OscarAyoy]

I just ran into this myself. It seems the src folder gets automatically ignored / excluded. I attempted to explicitly un-ignore the folder in a custom .melangeignore file, but had no success. In the end the easiest work-around was to simply rename the folder. This only applies to the melange-build action though. Works fine building locally using the Docker image.