Hi, On the occasion of the second Reproducible Builds workshop currently taking place in Berlin [1], I'm happy to announce that Hydra is now capable of repeating builds in order to test for certain types of binary reproducibility problems. Hydra can now be configured to run every build step in a jobset multiple times, comparing the result. If the result differs between rounds, the build step will still succeed, but the step will be marked as "Succeeded with non-deterministic result". (Thus reverse dependencies can still proceed.) For example:
http://hydra.nixos.org/build/44628665#tabs-buildsteps Furthermore, if there is a difference between rounds, diffoscope (a tool for comparing arbitrary directory trees [2]) is run on the the resulting store paths. For example, here is the build log for Samba: http://hydra.nixos.org/build/44628691/nixlog/2/raw The diffoscope output is at the end (starting at "diff with previous round"), showing that Samba stores a timestamp in lib/samba/libsmbd-base-samba4.so. Similarly, here is the log for python-urllib3: http://hydra.nixos.org/build/44713633/nixlog/4/raw This shows that the pip build tool uses a random temporary directory, which ends up in .pyc files. (This affects almost 1800 packages.) Currently, out of 36550 build steps in a full NixOS evaluation, only 4699 (12.8%) were detected as non-deterministic. (Note that Hydra can only detect the presence of non-determinism, not its absence). Here is the full list: http://nixos.org/~eelco/tmp/nondeterministic-build-steps.txt Currently only the nixos:reproducibility jobset runs build steps multiple times (twice, to be precise). [1] https://reproducible-builds.org/events/berlin2016/ [2] https://diffoscope.org/ -- Eelco Dolstra | LogicBlox, Inc. | http://nixos.org/~eelco/ _______________________________________________ nix-dev mailing list nix-dev@lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/nix-dev