Merge remote-tracking branch 'tweag/auto-update-flake' into flakes

8 files changed, 188 insertions, 20 deletions

diff --git a/src/libexpr/primops/flake.cc b/src/libexpr/primops/flake.cc
index 3998f9ef9..48a036875 100644
--- a/src/libexpr/primops/flake.cc
+++ b/src/libexpr/primops/flake.cc
@@ -3,7 +3,9 @@
 #include "eval-inline.hh"
 #include "fetchGit.hh"
 #include "download.hh"
+#include "args.hh"
 
+#include <iostream>
 #include <queue>
 #include <regex>
 #include <nlohmann/json.hpp>
@@ -31,6 +33,18 @@ static std::unique_ptr<FlakeRegistry> readRegistry(const Path & path)
     return registry;
 }
 
+/* Write the registry or lock file to a file. */
+void writeRegistry(FlakeRegistry registry, Path path)
+{
+    nlohmann::json json = {};
+    json["version"] = 1;
+    json["flakes"] = {};
+    for (auto elem : registry.entries) {
+        json["flakes"][elem.first] = elem.second.ref.to_string();
+    }
+    writeFile(path, json.dump(4)); // The '4' is the number of spaces used in the indentation in the json file.
+}
+
 const FlakeRegistry & EvalState::getFlakeRegistry()
 {
     std::call_once(_flakeRegistryInit, [&]()
@@ -95,9 +109,21 @@ struct FlakeSourceInfo
 
 static FlakeSourceInfo fetchFlake(EvalState & state, const FlakeRef & flakeRef)
 {
-    assert(flakeRef.isDirect());
+    FlakeRef directFlakeRef = FlakeRef(flakeRef);
+    if (!flakeRef.isDirect())
+    {
+        std::vector<const FlakeRegistry *> registries;
+        // 'pureEval' is a setting which cannot be changed in `nix flake`,
+        // but without flagging it off, we can't use any FlakeIds.
+        // if (!evalSettings.pureEval) {
+            registries.push_back(&state.getFlakeRegistry());
+        // }
+        directFlakeRef = lookupFlake(state, flakeRef, registries);
+    }
+    assert(directFlakeRef.isDirect());
+    // NOTE FROM NICK: I don't see why one wouldn't fetch FlakeId flakes..
 
-    if (auto refData = std::get_if<FlakeRef::IsGitHub>(&flakeRef.data)) {
+    if (auto refData = std::get_if<FlakeRef::IsGitHub>(&directFlakeRef.data)) {
         // FIXME: require hash in pure mode.
 
         // FIXME: use regular /archive URLs instead? api.github.com
@@ -129,7 +155,7 @@ static FlakeSourceInfo fetchFlake(EvalState & state, const FlakeRef & flakeRef)
         return info;
     }
 
-    else if (auto refData = std::get_if<FlakeRef::IsGit>(&flakeRef.data)) {
+    else if (auto refData = std::get_if<FlakeRef::IsGit>(&directFlakeRef.data)) {
         auto gitInfo = exportGit(state.store, refData->uri, refData->ref,
             refData->rev ? refData->rev->to_string(Base16, false) : "", "source");
         FlakeSourceInfo info;
@@ -141,20 +167,7 @@ static FlakeSourceInfo fetchFlake(EvalState & state, const FlakeRef & flakeRef)
     else abort();
 }
 
-struct Flake
-{
-    FlakeId id;
-    std::string description;
-    Path path;
-    std::vector<FlakeRef> requires;
-    std::unique_ptr<FlakeRegistry> lockFile;
-    Value * vProvides; // FIXME: gc
-    // commit hash
-    // date
-    // content hash
-};
-
-static Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
+Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
 {
     auto sourceInfo = fetchFlake(state, flakeRef);
     debug("got flake source '%s' with revision %s",
@@ -166,7 +179,16 @@ static Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
     if (state.allowedPaths)
         state.allowedPaths->insert(flakePath);
 
-    Flake flake;
+    FlakeRef newFlakeRef(flakeRef);
+    if (std::get_if<FlakeRef::IsGitHub>(&newFlakeRef.data)) {
+        FlakeSourceInfo srcInfo = fetchFlake(state, newFlakeRef);
+        if (srcInfo.rev) {
+            std::string uri = flakeRef.to_string();
+            newFlakeRef = FlakeRef(uri + "/" + srcInfo.rev->to_string());
+        }
+    }
+
+    Flake flake(newFlakeRef);
 
     Value vInfo;
     state.evalFile(flakePath + "/flake.nix", vInfo); // FIXME: symlink attack
@@ -259,6 +281,35 @@ static std::tuple<FlakeId, std::map<FlakeId, Flake>> resolveFlake(EvalState & st
     return {*topFlakeId, std::move(done)};
 }
 
+FlakeRegistry updateLockFile(EvalState & evalState, FlakeRef & flakeRef)
+{
+    FlakeRegistry newLockFile;
+    std::map<FlakeId, Flake> myDependencyMap = get<1>(resolveFlake(evalState, flakeRef, false));
+    // Nick assumed that "topRefPure" means that the Flake for flakeRef can be
+    // fetched purely.
+    for (auto const& require : myDependencyMap) {
+        FlakeRegistry::Entry entry = FlakeRegistry::Entry(require.second.ref);
+        // The FlakeRefs are immutable because they come out of the Flake objects,
+        // not from the requires.
+        newLockFile.entries.insert(std::pair<FlakeId, FlakeRegistry::Entry>(require.first, entry));
+    }
+    return newLockFile;
+}
+
+void updateLockFile(EvalState & state, std::string path)
+{
+    // 'path' is the path to the local flake repo.
+    FlakeRef flakeRef = FlakeRef("file://" + path);
+    if (std::get_if<FlakeRef::IsGit>(&flakeRef.data)) {
+        FlakeRegistry newLockFile = updateLockFile(state, flakeRef);
+        writeRegistry(newLockFile, path + "/flake.lock");
+    } else if (std::get_if<FlakeRef::IsGitHub>(&flakeRef.data)) {
+        throw UsageError("you can only update local flakes, not flakes on GitHub");
+    } else {
+        throw UsageError("you can only update local flakes, not flakes through their FlakeId");
+    }
+}
+
 Value * makeFlakeValue(EvalState & state, std::string flakeUri, Value & v)
 {
     // FIXME: temporary hack to make the default installation source
diff --git a/src/libexpr/primops/flake.hh b/src/libexpr/primops/flake.hh
index e504dc196..b3a755311 100644
--- a/src/libexpr/primops/flake.hh
+++ b/src/libexpr/primops/flake.hh
@@ -13,6 +13,7 @@ struct FlakeRegistry
     struct Entry
     {
         FlakeRef ref;
+        Entry(const FlakeRef & flakeRef) : ref(flakeRef) {};
     };
     std::map<FlakeId, Entry> entries;
 };
@@ -21,4 +22,26 @@ Value * makeFlakeRegistryValue(EvalState & state);
 
 Value * makeFlakeValue(EvalState & state, std::string flakeUri, Value & v);
 
+void writeRegistry(FlakeRegistry, Path);
+
+struct Flake
+{
+    FlakeId id;
+    FlakeRef ref;
+    std::string description;
+    Path path;
+    std::vector<FlakeRef> requires;
+    std::unique_ptr<FlakeRegistry> lockFile;
+    Value * vProvides; // FIXME: gc
+    // commit hash
+    // date
+    // content hash
+    Flake(FlakeRef & flakeRef) : ref(flakeRef) {};
+};
+
+Flake getFlake(EvalState &, const FlakeRef &);
+
+FlakeRegistry updateLockFile(EvalState &, Flake &);
+
+void updateLockFile(EvalState &, std::string);
 }
diff --git a/src/libexpr/primops/flakeref.hh b/src/libexpr/primops/flakeref.hh
index ad0cf8630..4d1756b49 100644
--- a/src/libexpr/primops/flakeref.hh
+++ b/src/libexpr/primops/flakeref.hh
@@ -129,6 +129,9 @@ struct FlakeRef
     // Parse a flake URI.
     FlakeRef(const std::string & uri);
 
+    // Default constructor
+    FlakeRef(const FlakeRef & flakeRef) : data(flakeRef.data) {};
+
     /* Unify two flake references so that the resulting reference
        combines the information from both. For example,
        "nixpkgs/<hash>" and "github:NixOS/nixpkgs" unifies to
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index e3dcd246c..b0a2b853e 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -344,7 +344,6 @@ void writeFile(const Path & path, Source & source, mode_t mode)
     }
 }
 
-
 string readLine(int fd)
 {
     string s;
diff --git a/src/nix/build.cc b/src/nix/build.cc
index b329ac38a..5ab22e26c 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -1,3 +1,5 @@
+#include "primops/flake.hh"
+#include "eval.hh"
 #include "command.hh"
 #include "common-args.hh"
 #include "shared.hh"
@@ -9,6 +11,8 @@ struct CmdBuild : MixDryRun, InstallablesCommand
 {
     Path outLink = "result";
 
+    std::optional<std::string> gitRepo = std::nullopt;
+
     CmdBuild()
     {
         mkFlag()
@@ -22,6 +26,11 @@ struct CmdBuild : MixDryRun, InstallablesCommand
             .longName("no-link")
             .description("do not create a symlink to the build result")
             .set(&outLink, Path(""));
+
+        mkFlag()
+            .longName("update-lock-file")
+            .description("update the lock file")
+            .dest(&gitRepo);
     }
 
     std::string name() override
@@ -52,6 +61,8 @@ struct CmdBuild : MixDryRun, InstallablesCommand
     {
         auto buildables = build(store, dryRun ? DryRun : Build, installables);
 
+        auto evalState = std::make_shared<EvalState>(searchPath, store);
+
         if (dryRun) return;
 
         for (size_t i = 0; i < buildables.size(); ++i) {
@@ -66,6 +77,9 @@ struct CmdBuild : MixDryRun, InstallablesCommand
                         store2->addPermRoot(output.second, absPath(symlink), true);
                     }
         }
+
+        if(gitRepo)
+            updateLockFile(*evalState, *gitRepo);
     }
 };
 
diff --git a/src/nix/command.hh b/src/nix/command.hh
index a08347945..c58d5d56e 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -34,6 +34,26 @@ struct Buildable
 
 typedef std::vector<Buildable> Buildables;
 
+struct GitRepoCommand : virtual Args
+{
+    std::string gitPath = absPath(".");
+
+    GitRepoCommand ()
+    {
+        expectArg("git-path", &gitPath, true);
+    }
+};
+
+struct FlakeCommand : virtual Args, StoreCommand, MixEvalArgs
+{
+    std::string flakeUri;
+
+    FlakeCommand()
+    {
+        expectArg("flake-uri", &flakeUri);
+    }
+};
+
 struct Installable
 {
     virtual std::string what() = 0;
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 9b36c3cbd..a5a1d34db 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -4,6 +4,7 @@
 #include "shared.hh"
 #include "progress-bar.hh"
 #include "eval.hh"
+#include <nlohmann/json.hpp>
 
 using namespace nix;
 
@@ -33,10 +34,66 @@ struct CmdFlakeList : StoreCommand, MixEvalArgs
     }
 };
 
+struct CmdFlakeUpdate : StoreCommand, GitRepoCommand, MixEvalArgs
+{
+    std::string name() override
+    {
+        return "update";
+    }
+
+    std::string description() override
+    {
+        return "update flake lock file";
+    }
+
+    void run(nix::ref<nix::Store> store) override
+    {
+        auto evalState = std::make_shared<EvalState>(searchPath, store);
+
+        if (flakeUri == "") flakeUri = absPath("./flake.nix");
+        int result = updateLockFile(*evalState, flakeUri);
+        if (result == 1) {
+            std::cout << "You can only update local flakes, not flakes on GitHub.\n";
+        } else if (result == 2) {
+            std::cout << "You can only update local flakes, not flakes through their FlakeId.\n";
+        }
+    }
+};
+
+struct CmdFlakeInfo : FlakeCommand, MixJSON
+{
+    std::string name() override
+    {
+        return "info";
+    }
+
+    std::string description() override
+    {
+        return "list info about a given flake";
+    }
+
+    void run(nix::ref<nix::Store> store) override
+    {
+        auto evalState = std::make_shared<EvalState>(searchPath, store);
+        nix::Flake flake = nix::getFlake(*evalState, FlakeRef(flakeUri));
+        if (json) {
+            nlohmann::json j;
+            j["location"] = flake.path;
+            j["description"] = flake.description;
+            std::cout << j.dump(4) << std::endl;
+        } else {
+            std::cout << "Description: " << flake.description << "\n";
+            std::cout << "Location:    " << flake.path << "\n";
+        }
+    }
+};
+
 struct CmdFlake : virtual MultiCommand, virtual Command
 {
     CmdFlake()
-        : MultiCommand({make_ref<CmdFlakeList>()})
+        : MultiCommand({make_ref<CmdFlakeList>()
+            , make_ref<CmdFlakeInfo>()
+            , make_ref<CmdFlakeUpdate>()})
     {
     }
 
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index 0453c72c2..21e9e73b8 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -234,6 +234,7 @@ Buildables build(ref<Store> store, RealiseMode mode,
     PathSet pathsToBuild;
 
     for (auto & i : installables) {
+        std::cout << i->what() << std::endl;
         for (auto & b : i->toBuildables()) {
             if (b.drvPath != "") {
                 StringSet outputNames;