Eelco Dolstra
1511aa9f48
Previously, to build a derivation remotely, we had to copy the entire closure of the .drv file to the remote machine, even though we only need the top-level derivation. This is very wasteful: the closure can contain thousands of store paths, and in some Hydra use cases, include source paths that are very large (e.g. Git/Mercurial checkouts). So now there is a new operation, StoreAPI::buildDerivation(), that performs a build from an in-memory representation of a derivation (BasicDerivation) rather than from a on-disk .drv file. The only files that need to be in the Nix store are the sources of the derivation (drv.inputSrcs), and the needed output paths of the dependencies (as described by drv.inputDrvs). "nix-store --serve" exposes this interface. Note that this is a privileged operation, because you can construct a derivation that builds any store path whatsoever. Fixing this will require changing the hashing scheme (i.e., the output paths should be computed from the other fields in BasicDerivation, allowing them to be verified without access to other derivations). However, this would be quite nice because it would allow .drv-free building (e.g. "nix-env -i" wouldn't have to write any .drv files to disk). Fixes #173.
Nix is a purely functional package manager. For installation and usage instructions, please read the manual, which can be found in `docs/manual/manual.html', and additionally at the Nix website at <http://nixos.org/>. Acknowledgments This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.OpenSSL.org/).