diff --git a/src/nix/flake-prefetch-inputs.cc b/src/nix/flake-prefetch-inputs.cc new file mode 100644 index 000000000..096eaf539 --- /dev/null +++ b/src/nix/flake-prefetch-inputs.cc @@ -0,0 +1,72 @@ +#include "flake-command.hh" +#include "nix/fetchers/fetch-to-store.hh" +#include "nix/util/thread-pool.hh" +#include "nix/store/filetransfer.hh" +#include "nix/util/exit.hh" + +#include + +using namespace nix; +using namespace nix::flake; + +struct CmdFlakePrefetchInputs : FlakeCommand +{ + std::string description() override + { + return "fetch the inputs of a flake"; + } + + std::string doc() override + { + return +#include "flake-prefetch-inputs.md" + ; + } + + void run(nix::ref store) override + { + auto flake = lockFlake(); + + ThreadPool pool{fileTransferSettings.httpConnections}; + + struct State + { + std::set done; + }; + + Sync state_; + + std::atomic nrFailed{0}; + + std::function visit; + visit = [&](const Node & node) { + if (!state_.lock()->done.insert(&node).second) + return; + + if (auto lockedNode = dynamic_cast(&node)) { + try { + Activity act(*logger, lvlInfo, actUnknown, fmt("fetching '%s'", lockedNode->lockedRef)); + auto accessor = lockedNode->lockedRef.input.getAccessor(store).first; + fetchToStore( + fetchSettings, *store, accessor, FetchMode::Copy, lockedNode->lockedRef.input.getName()); + } catch (Error & e) { + printError("%s", e.what()); + nrFailed++; + } + } + + for (auto & [inputName, input] : node.inputs) { + if (auto inputNode = std::get_if<0>(&input)) + pool.enqueue(std::bind(visit, **inputNode)); + } + }; + + pool.enqueue(std::bind(visit, *flake.lockFile.root)); + + pool.process(); + + throw Exit(nrFailed ? 1 : 0); + } +}; + +static auto rCmdFlakePrefetchInputs = registerCommand2({"flake", "prefetch-inputs"}); diff --git a/src/nix/flake-prefetch-inputs.md b/src/nix/flake-prefetch-inputs.md new file mode 100644 index 000000000..a69f7d367 --- /dev/null +++ b/src/nix/flake-prefetch-inputs.md @@ -0,0 +1,17 @@ +R""( + +# Examples + +* Fetch the inputs of the `hydra` flake: + + ```console + # nix flake prefetch-inputs github:NixOS/hydra + ``` + +# Description + +Fetch the inputs of a flake. This ensures that they are already available for any subsequent evaluation of the flake. + +This operation is recursive: it will fetch not just the direct inputs of the top-level flake, but also transitive inputs. + +)"" diff --git a/src/nix/meson.build b/src/nix/meson.build index 586ee15c3..f1c79b002 100644 --- a/src/nix/meson.build +++ b/src/nix/meson.build @@ -78,6 +78,7 @@ nix_sources = [config_priv_h] + files( 'env.cc', 'eval.cc', 'flake.cc', + 'flake-prefetch-inputs.cc', 'formatter.cc', 'hash.cc', 'log.cc',