unisonweb
CI: populate nix cache for aarch64-linux
Currently the nix flake marks aarch64-linux as a supported system, but our Nix development cache CI job doesn't publish to the nix cache for aarch64-linux. When I attempted to make it publish for ARM linux, the build repeatedly timed out after an hour; no incremental results seem to be saved.
See this discussion.
Yeah, it would be nice if we could cache incrementally, so then repeated builds would make progress.
For the time being, I’ve relied on pushing to the cache manually after building locally (#5795). The issue is having someone who has both some interest in the Nix build and a machine that’ll build aarch64-linux.
The problem is that the initial build will build GHC, etc. and time out on GiHub, so someone has to do an aarch64-linux build elsewhere, then push to Cachix so GitHub can just fetch everything.
One thing that I've noticed but haven't been able to understand is that the builds time out after an hour but the GitHub actions docs say that the timeout for a job is higher (I think 6 hours?). And in my unison-nix repo it gets through a 2+ hour build of ucm on aarch64-linux runners https://github.com/ceedubs/unison-nix/actions/runs/18012578621