Merge remote-tracking branch 'origin/master' into lazy-trees

doc/manual/src/release-notes/rl-next.md

@@ -11,6 +11,48 @@
  a context just because they are read from a store path
  ([#7260](https://github.com/NixOS/nix/pull/7260)).
 
+* Nix can now automatically pick UIDs for builds, removing the need to
+ create `nixbld*` user accounts. These UIDs are allocated starting at
+ 872415232 (0x34000000) on Linux and 56930 on macOS.
+
+ This is an experimental feature. To enable it, add the following to
+ `nix.conf`:
+
+ ```
+ extra-experimental-features = auto-allocate-uids
+ auto-allocate-uids = true
+ ```
+
+* On Linux, Nix can now run builds in a user namespace where the build
+ runs as root (UID 0) and has 65,536 UIDs available. This is
+ primarily useful for running containers such as `systemd-nspawn`
+ inside a Nix build. For an example, see
+ https://github.com/NixOS/nix/blob/67bcb99700a0da1395fa063d7c6586740b304598/tests/systemd-nspawn.nix.
+
+ A build can enable this by requiring the `uid-range` system feature,
+ i.e. by setting the derivation attribute
+
+ ```
+ requiredSystemFeatures = [ "uid-range" ];
+ ```
+
+ The `uid-range` system feature requires the `auto-allocate-uids`
+ setting to be enabled (see above).
+
+* On Linux, Nix has experimental support for running builds inside a
+ cgroup. It can be enabled by adding
+
+ ```
+ extra-experimental-features = cgroups
+ use-cgroups = true
+ ```
+
+ to `nix.conf`. Cgroups are required for derivations that require the
+ `uid-range` system feature.
+
+* `nix build --json` now prints some statistics about top-level
+ derivations, such as CPU statistics when cgroups are enabled.
+
 * You can now use flake references in the old CLI, e.g.
 
  ```

src/libexpr/eval.cc

@@ -2482,9 +2482,9 @@ void EvalState::printStats()
  obj["name"] = nullptr;
  if (auto pos = positions[fun->pos]) {
  if (auto path = std::get_if<SourcePath>(&pos.origin))
- obj.attr("file", path->to_string());
- obj.attr("line", pos.line);
- obj.attr("column", pos.column);
+ obj["file"] = path->to_string();
+ obj["line"] = pos.line;
+ obj["column"] = pos.column;
  }
  obj["count"] = count;
  list.push_back(obj);
@@ -2497,9 +2497,9 @@ void EvalState::printStats()
  json obj = json::object();
  if (auto pos = positions[i.first]) {
  if (auto path = std::get_if<SourcePath>(&pos.origin))
- obj.attr("file", path->to_string());
- obj.attr("line", pos.line);
- obj.attr("column", pos.column);
+ obj["file"] = path->to_string();
+ obj["line"] = pos.line;
+ obj["column"] = pos.column;
  }
  obj["count"] = i.second;
  list.push_back(obj);

src/libexpr/value-to-json.cc

@@ -36,11 +36,10 @@ json printValueAsJSON(EvalState & state, bool strict,
 
  case nPath:
  if (copyToStore)
- out.write(
- state.store->printStorePath(
- state.copyPathToStore(context, v.path())));
+ out = state.store->printStorePath(
+ state.copyPathToStore(context, v.path()));
  else
- out.write(v.path().path.abs());
+ out = v.path().path.abs();
  break;
 
  case nNull:

src/nix/flake.cc

@@ -912,18 +912,11 @@ struct CmdFlakeArchive : FlakeCommand, MixJSON
 
  auto flake = lockFlake();
 
- auto jsonRoot = json ? std::optional<JSONObject>(std::cout) : std::nullopt;
-
- {
- Activity act(*logger, lvlChatty, actUnknown, fmt("archiving root"));
- auto storePath = flake.flake.lockedRef.input.fetchToStore(dstStore).first;
- if (jsonRoot)
- jsonRoot->attr("path", store->printStorePath(storePath));
- }
+ auto jsonRoot = json ? std::optional<nlohmann::json>() : std::nullopt;
 
  // FIXME: use graph output, handle cycles.
- std::function<void(const Node & node, const InputPath & parentPath, std::optional<JSONObject> & jsonObj)> traverse;
- traverse = [&](const Node & node, const InputPath & parentPath, std::optional<JSONObject> & jsonObj)
+ std::function<nlohmann::json(const Node & node, const InputPath & parentPath)> traverse;
+ traverse = [&](const Node & node, const InputPath & parentPath)
  {
  nlohmann::json jsonObj2 = json ? json::object() : nlohmann::json(nullptr);
  for (auto & [inputName, input] : node.inputs) {
@@ -932,17 +925,29 @@ struct CmdFlakeArchive : FlakeCommand, MixJSON
  inputPath.push_back(inputName);
  Activity act(*logger, lvlChatty, actUnknown,
  fmt("archiving input '%s'", printInputPath(inputPath)));
- auto jsonObj3 = jsonObj2 ? jsonObj2->object(inputName) : std::optional<JSONObject>();
  auto storePath = (*inputNode)->lockedRef.input.fetchToStore(dstStore).first;
- if (jsonObj3)
- jsonObj3->attr("path", store->printStorePath(storePath));
- traverse(**inputNode, inputPath, jsonObj3);
+ auto res = traverse(**inputNode, inputPath);
+ if (json) {
+ auto & jsonObj3 = jsonObj2[inputName];
+ jsonObj3["path"] = store->printStorePath(storePath);
+ jsonObj3["inputs"] = res;
+ }
  }
  }
  return jsonObj2;
  };
 
- traverse(*flake.lockFile.root, {}, jsonRoot);
+ auto res = traverse(*flake.lockFile.root, {});
+
+ if (json) {
+ Activity act(*logger, lvlChatty, actUnknown, fmt("archiving root"));
+ auto storePath = flake.flake.lockedRef.input.fetchToStore(dstStore).first;
+ nlohmann::json jsonRoot = {
+ {"path", store->printStorePath(storePath)},
+ {"inputs", res},
+ };
+ std::cout << jsonRoot.dump() << std::endl;
+ }
  }
 };