Travis build fails: "Read-only file system"

[rschmitt]

Heatseeker has a build script that collects some build-time metadata and writes a version.rs file. After migrating to trust, Travis builds (except for builds targeting Darwin) are failing with the following error:

error: failed to run custom build command for `heatseeker v1.5.0 (file:///project)`
process didn't exit successfully: `/target/debug/build/heatseeker-77dc6031b5733332/build-script-build` (exit code: 101)
--- stderr
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error { repr: Os { code: 30, message: "Read-only file system" } }', ../src/libcore/result.rs:837

The custom build command never caused any problems before, and somehow it's still not causing problems for Darwin builds. I'm not sure if the problem is in the trust template, my adaptation of it, or Travis itself.

[japaric]

This is because cross, which uses Docker under the hood (only for Linux), mounts the Cargo project as read only. That's why the build script fails.

Build scripts shouldn't modify the src directory as that can mess up Cargo "freshness" check which in turn can cause consecutive cargo builds to always rebuild the crate.

The "proper" way to pass version information is to write to a file in the target directory (OUT_DIR) and then include_str that into your source.

[rschmitt]

Thanks, this saved me a lot of time. I noticed that git rev-parse no longer runs on the Linux builds; I assume this means that cross's Docker images don't include git?

[japaric]

this means that cross's Docker images don't include git?

They don't. I think they should, to support this pattern.

[maccoda]

I am getting the same error but mine is due to the integration test I am running which produces a file as the output. I have tried writing outside of the source directory using ../out and for this I do not have permission, then writing into target as the build does still returned Read-only file system. So I was just wondering is there a way to actually test this in the Docker image or will I just not be able to run these tests on this CI?

[japaric]

... which produces a file as the output.

You should be writing this file to a temporary directory with delete-on-drop semantics. That's the standard-ish practice. Check the tempdir crate.

[maccoda]

Thanks for that. Will give that a go.

[hoodie]

hey, do we want to add git to the Dockerfiles? I kinda already did the work hoodie/cross@a6eed71