chore: bump nix go to 1.25.4 (#19817)

Makefile

@@ -893,3 +893,13 @@ update-loki-release-sha:
 	mv .github/jsonnetfile.json.tmp .github/jsonnetfile.json
 	@echo "Updated successfully"
 	@$(MAKE) release-workflows
+
+.PHONY: flake-update
+flake-update:
+	@docker run -v $(CURDIR):/loki \
+		--workdir /loki \
+		nixos/nix \
+		nix \
+		--extra-experimental-features nix-command \
+		--extra-experimental-features flakes \
+		flake update

flake.lock

@@ -20,16 +20,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1762361079,
-        "narHash": "sha256-lz718rr1BDpZBYk7+G8cE6wee3PiBUpn8aomG/vLLiY=",
+        "lastModified": 1762498405,
+        "narHash": "sha256-Zg/SCgCaAioc0/SVZQJxuECGPJy+OAeBcGeA5okdYDc=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "ffcdcf99d65c61956d882df249a9be53e5902ea5",
+        "rev": "6faeb062ee4cf4f105989d490831713cc5a43ee1",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "nixpkgs-unstable",
+        "ref": "nixos-25.05",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -2,7 +2,7 @@
   description = "Grafana Loki";
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.05";
     flake-utils.url = "github:numtide/flake-utils";
   };
 
@@ -16,13 +16,13 @@
           };
       in
       rec {
-        defaultPackage = pkgs.loki;
-
         packages = import ./nix {
           inherit self pkgs;
           inherit (pkgs) lib;
         };
 
+        defaultPackage = packages.loki;
+
         apps = {
           lint = {
             type = "app";
@@ -44,7 +44,7 @@
 
             chart-testing
             gcc
-            go
+            go_1_25
             golangci-lint
             gotools
             helm-docs
@@ -52,7 +52,7 @@
             nixpkgs-fmt
             statix
             yamllint
-          ] // packages;
+          ] ++ (builtins.attrValues packages);
         };
       });
 }

nix/default.nix

@@ -32,7 +32,8 @@ let
 
   loki-helm-test = pkgs.callPackage ../production/helm/loki/src/helm-test {
     inherit pkgs;
-    inherit (pkgs) lib buildGoModule dockerTools;
+    inherit (pkgs) lib dockerTools;
+    buildGoModule = pkgs.buildGo125Module;
     rev = gitRevision;
   };
 in

production/helm/loki/src/helm-test/canary_test.go

@@ -129,7 +129,7 @@ func testResultCanary(t *testing.T, ctx context.Context, metric string, test fun
 	body, err := io.ReadAll(rsp.Body)
 	require.NoError(t, err, "Failed to read response body")
 
-	p, err := textparse.New(body, rsp.Header.Get("Content-Type"), true, false, nil)
+	p, err := textparse.New(body, rsp.Header.Get("Content-Type"), "", true, false, true, labels.NewSymbolTable())
 	require.NoError(t, err, "Failed to create Prometheus parser")
 
 	for {
@@ -142,8 +142,8 @@ func testResultCanary(t *testing.T, ctx context.Context, metric string, test fun
 			continue
 		}
 
-		l := labels.Labels{}
-		p.Metric(&l)
+		var l labels.Labels
+		p.Labels(&l)
 
 		// Currently we aren't validating any labels, just the metric name, however this could be extended to do so.
 		name := l.Get(model.MetricNameLabel)