Make nix path-info follow the JSON guidelines

doc/manual/rl-next/json-format-changes.md

@@ -18,16 +18,30 @@ This is the legacy format, preserved for backwards compatibility:
 
 - String-based hash values (e.g., `"narHash": "sha256:FePFYIlM..."`)
 - String-based content addresses (e.g., `"ca": "fixed:r:sha256:1abc..."`)
-- Full store paths in references (e.g., `"/nix/store/abc...-foo"`)
+- Full store paths for map keys and references (e.g., `"/nix/store/abc...-foo"`)
 - Now includes `"storeDir"` field at the top level
 
 ### Version 2 (`--json-format 2`)
 
-The new structured format with the following changes:
+The new structured format follows the [JSON guidelines](@docroot@/development/json-guideline.md) with the following changes:
 
-- **Store path base names in references**:
+- **Nested structure with top-level metadata**:
 
-  References use store path base names (e.g., `"abc...-foo"`) instead of full paths.
+  The output is now wrapped in an object with `version`, `storeDir`, and `info` fields:
+
+  ```json
+  {
+    "version": 2,
+    "storeDir": "/nix/store",
+    "info": { ... }
+  }
+  ```
+
+  The map from store bath base names to store object info is nested under the `info` field.
+
+- **Store path base names instead of full paths**:
+
+  Map keys and references use store path base names (e.g., `"abc...-foo"`) instead of full absolute store paths.
   Combined with `storeDir`, the full path can be reconstructed.
 
 - **Structured `ca` field**:

src/nix/path-info.cc

@@ -41,18 +41,22 @@ pathInfoToJSON(Store & store, const StorePathSet & storePaths, bool showClosureS
 {
     json::object_t jsonAllObjects = json::object();
 
+    auto makeKey = [&](const StorePath & path) {
+        return format == PathInfoJsonFormat::V1 ? store.printStorePath(path) : std::string(path.to_string());
+    };
+
     for (auto & storePath : storePaths) {
         json jsonObject;
 
-        std::string key = store.printStorePath(storePath);
+        std::string key = makeKey(storePath);
 
         try {
             auto info = store.queryPathInfo(storePath);
 
             // `storePath` has the representation `<hash>-x` rather than
             // `<hash>-<name>` in case of binary-cache stores & `--all` because we don't
             // know the name yet until we've read the NAR info.
-            key = store.printStorePath(info->path);
+            key = makeKey(info->path);
 
             jsonObject = info->toJSON(format == PathInfoJsonFormat::V1 ? &store : nullptr, true, format);
 
@@ -87,7 +91,16 @@ pathInfoToJSON(Store & store, const StorePathSet & storePaths, bool showClosureS
 
         jsonAllObjects[key] = std::move(jsonObject);
     }
-    return jsonAllObjects;
+
+    if (format == PathInfoJsonFormat::V1) {
+        return jsonAllObjects;
+    } else {
+        return {
+            {"version", format},
+            {"storeDir", store.storeDir},
+            {"info", std::move(jsonAllObjects)},
+        };
+    }
 }
 
 struct CmdPathInfo : StorePathsCommand, MixJSON

tests/functional/binary-cache.sh

@@ -18,7 +18,7 @@ outPath=$(nix-build dependencies.nix --no-out-link)
 
 nix copy --to "file://$cacheDir" "$outPath"
 
-readarray -t paths < <(nix path-info --all --json --json-format 2 --store "file://$cacheDir" | jq 'keys|sort|.[]' -r)
+readarray -t paths < <(nix path-info --all --json --json-format 2 --store "file://$cacheDir" | jq '.info|keys|sort|.[]' -r)
 [[ "${#paths[@]}" -eq 3 ]]
 for path in "${paths[@]}"; do
     [[ "$path" =~ -dependencies-input-0$ ]] \

tests/functional/fixed.sh

@@ -15,7 +15,7 @@ nix-build fixed.nix -A bad --no-out-link && fail "should fail"
 # a side-effect.
 [[ -e $path ]]
 nix path-info --json --json-format 2 "$path" | jq -e \
-    '.[].ca == {
+    '.info.[].ca == {
         method: "flat",
         hash: {
             algorithm: "md5",

tests/functional/git-hashing/simple-common.sh

@@ -50,7 +50,7 @@ try2 () {
     nix path-info --json --json-format 2 "$path" | jq -e \
         --arg algo "$hashAlgo" \
         --arg hash "$hashFromGit" \
-        '.[].ca == {
+        '.info.[].ca == {
             method: "git",
             hash: {
                 algorithm: $algo,

tests/functional/impure-derivations.sh

@@ -30,7 +30,7 @@ path1_stuff=$(echo "$json" | jq -r .[].outputs.stuff)
 [[ $(< "$path1"/n) = 0 ]]
 [[ $(< "$path1_stuff"/bla) = 0 ]]
 
-nix path-info --json --json-format 2 "$path1" | jq -e '.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
+nix path-info --json --json-format 2 "$path1" | jq -e '.info.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
 
 path2=$(nix build -L --no-link --json --file ./impure-derivations.nix impure | jq -r .[].outputs.out)
 [[ $(< "$path2"/n) = 1 ]]

tests/functional/nix-profile.sh

@@ -166,7 +166,7 @@ printf 4.0 > "$flake1Dir"/version
 printf Utrecht > "$flake1Dir"/who
 nix profile add "$flake1Dir"
 [[ $("$TEST_HOME"/.nix-profile/bin/hello) = "Hello Utrecht" ]]
-nix path-info --json --json-format 2 "$(realpath "$TEST_HOME"/.nix-profile/bin/hello)" | jq -e '.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
+nix path-info --json --json-format 2 "$(realpath "$TEST_HOME"/.nix-profile/bin/hello)" | jq -e '.info.[].ca | .method == "nar" and .hash.algorithm == "sha256"'
 
 # Override the outputs.
 nix profile remove simple flake1

tests/functional/path-info.sh

@@ -4,36 +4,44 @@ source common.sh
 
 echo foo > "$TEST_ROOT"/foo
 foo=$(nix store add-file "$TEST_ROOT"/foo)
+fooBase=$(basename "$foo")
 
 echo bar > "$TEST_ROOT"/bar
 bar=$(nix store add-file "$TEST_ROOT"/bar)
+barBase=$(basename "$bar")
 
 echo baz > "$TEST_ROOT"/baz
 baz=$(nix store add-file "$TEST_ROOT"/baz)
+bazBase=$(basename "$baz")
 nix-store --delete "$baz"
 
 diff --unified --color=always \
     <(nix path-info --json --json-format 2 "$foo" "$bar" "$baz" |
-        jq --sort-keys 'map_values(.narHash)') \
+        jq --sort-keys '.info | map_values(.narHash)') \
     <(jq --sort-keys <<-EOF
         {
-          "$foo": {
+          "$fooBase": {
             "algorithm": "sha256",
             "format": "base16",
             "hash": "42fb4031b525feebe2f8b08e6e6a8e86f34e6a91dd036ada888e311b9cc8e690"
           },
-          "$bar": {
+          "$barBase": {
             "algorithm": "sha256",
             "format": "base16",
             "hash": "f5f8581aef5fab17100b629cf35aa1d91328d5070b054068f14fa93e7fa3b614"
           },
-          "$baz": null
+          "$bazBase": null
         }
 EOF
     )
 
-# Test that storeDir is returned in the JSON output
+# Test that storeDir is returned in the JSON output in individual store objects
 nix path-info --json --json-format 2 "$foo" | jq -e \
-    --arg foo "$foo" \
+    --arg fooBase "$fooBase" \
     --arg storeDir "${NIX_STORE_DIR:-/nix/store}" \
-    '.[$foo].storeDir == $storeDir'
+    '.info[$fooBase].storeDir == $storeDir'
+
+# And also at the top -evel
+echo | nix path-info --json --json-format 2 --stdin | jq -e \
+    --arg storeDir "${NIX_STORE_DIR:-/nix/store}" \
+    '.storeDir == $storeDir'

tests/functional/signing.sh

@@ -15,10 +15,10 @@ outPath=$(nix-build dependencies.nix --no-out-link --secret-key-files "$TEST_ROO
 
 # Verify that the path got signed.
 info=$(nix path-info --json --json-format 2 "$outPath")
-echo "$info" | jq -e '.[] | .ultimate == true'
+echo "$info" | jq -e '.info.[] | .ultimate == true'
 TODO_NixOS # looks like an actual bug? Following line fails on NixOS:
-echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache1.example.org"))'
-echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache2.example.org"))'
+echo "$info" | jq -e '.info.[] | .signatures.[] | select(startswith("cache1.example.org"))'
+echo "$info" | jq -e '.info.[] | .signatures.[] | select(startswith("cache2.example.org"))'
 
 # Test "nix store verify".
 nix store verify -r "$outPath"
@@ -40,8 +40,8 @@ nix store verify -r "$outPath"
 
 # Verify that the path did not get signed but does have the ultimate bit.
 info=$(nix path-info --json --json-format 2 "$outPath2")
-echo "$info" | jq -e '.[] | .ultimate == true'
-echo "$info" | jq -e '.[] | .signatures == []'
+echo "$info" | jq -e '.info.[] | .ultimate == true'
+echo "$info" | jq -e '.info.[] | .signatures == []'
 
 # Test "nix store verify".
 nix store verify -r "$outPath2"
@@ -58,7 +58,7 @@ nix store verify -r "$outPath2" --sigs-needed 1 --trusted-public-keys "$pk1"
 # Build something content-addressed.
 outPathCA=$(IMPURE_VAR1=foo IMPURE_VAR2=bar nix-build ./fixed.nix -A good.0 --no-out-link)
 
-nix path-info --json --json-format 2 "$outPathCA" | jq -e '.[].ca | .method == "flat" and .hash.algorithm == "md5"'
+nix path-info --json --json-format 2 "$outPathCA" | jq -e '.info.[].ca | .method == "flat" and .hash.algorithm == "md5"'
 
 # Content-addressed paths don't need signatures, so they verify
 # regardless of --sigs-needed.
@@ -74,15 +74,15 @@ nix copy --to file://"$cacheDir" "$outPath2"
 
 # Verify that signatures got copied.
 info=$(nix path-info --store file://"$cacheDir" --json --json-format 2 "$outPath2")
-echo "$info" | jq -e '.[] | .ultimate == false'
-echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache1.example.org"))'
-echo "$info" | expect 4 jq -e '.[] | .signatures.[] | select(startswith("cache2.example.org"))'
+echo "$info" | jq -e '.info.[] | .ultimate == false'
+echo "$info" | jq -e '.info.[] | .signatures.[] | select(startswith("cache1.example.org"))'
+echo "$info" | expect 4 jq -e '.info.[] | .signatures.[] | select(startswith("cache2.example.org"))'
 
 # Verify that adding a signature to a path in a binary cache works.
 nix store sign --store file://"$cacheDir" --key-file "$TEST_ROOT"/sk2 "$outPath2"
 info=$(nix path-info --store file://"$cacheDir" --json --json-format 2 "$outPath2")
-echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache1.example.org"))'
-echo "$info" | jq -e '.[] | .signatures.[] | select(startswith("cache2.example.org"))'
+echo "$info" | jq -e '.info.[] | .signatures.[] | select(startswith("cache1.example.org"))'
+echo "$info" | jq -e '.info.[] | .signatures.[] | select(startswith("cache2.example.org"))'
 
 # Copying to a diverted store should fail due to a lack of signatures by trusted keys.
 chmod -R u+w "$TEST_ROOT"/store0 || true