[question] Sharing ~/.conan/data among Docker containers

We’re going to use Docker containers to provide stable build environments for C++ projects. Third party dependencies are pre-built and packaged into Conan packages. I’d like to share Conan cache among containers in order not to download packages each time new container is started. But I don’t want to share Conan settings (profiles, remotes, etc.) as it’s a part of build environment.

Is it possible/safe to share ~/.conan/data among multiple containers having different Conan settings in ~/.conan?

• I’ve read the CONTRIBUTING guide.

[memsharded]

A note @czoido, concurrency will only be limited to same computer concurrency. All the synchronization mechanisms that we can use (with a reasonable approach), only works for the same machine (semaphores, mutexes, file locking… only works at the machine level, not inter machine). So anything that means that the same cache is shared among different containers will not be concurrent safe.

Assuming there is perfect and exclusive sequential access to the cache, in the current cache, yes, there could also be issues (different machines continuoesly overwriting the same package with different revisions, as the cache can only store 1 revision). With the new 2.0 cache, that uses revisions, this might not happen. But the concurrency hypothesis must hold in practice, and I guess it is unlikely to always hold (for CI, almost impossible, for developer boxes, like a developer is not going to switch to another container to test something while the other container is building other thing in the same shared cache…)

[memsharded]

Yes, we are exploring other synchronization mechanisms besides fasteners for 2.0. We might keep with fasteners, but this is unknown atm.