chore: udate minimum Go version to 1.26 (#5461)

Bumps `.github/workflows`, `promu` and UI build container  to 1.27. We 
generally keep the minimum required version (1.26) and these versions 
exactly one minor version apart.

Fixes done via `golanglint-ci run --fix`.

Also bumps GOLANGCI_LINT_VERSION. This version is required, 
since the previous was not compatible with Go 1.27.

Signed-off-by: Christoph Maser <christoph.maser+github@gmail.com>
Signed-off-by: Solomon Jacobs <solomonjacobs@protonmail.com>
Co-authored-by: Solomon Jacobs <solomonjacobs@protonmail.com>

Author: TheMeier

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
     # should also be updated.
     container:
 
-      image: quay.io/prometheus/golang-builder:1.26-base
+      image: quay.io/prometheus/golang-builder:1.27-base
     services:
       maildev-noauth:
         image: maildev/maildev:2.2.1

.github/workflows/mixin.yml

@@ -19,7 +19,7 @@ jobs:
       - name: install Go
         uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7.0.0
         with:
-          go-version: 1.26.x
+          go-version: 1.27.x
       # pin the mixtool version until https://github.com/monitoring-mixins/mixtool/issues/135 is merged.
       - run: go install github.com/monitoring-mixins/mixtool/cmd/mixtool@2282201396b69055bb0f92f187049027a16d2130
       - run: go install github.com/google/go-jsonnet/cmd/jsonnetfmt@latest

.golangci.yml

@@ -96,7 +96,8 @@ formatters:
     - goimports
   settings:
     gofumpt:
-      extra-rules: true
+      extra:
+        group-params: true
     goimports:
       local-prefixes:
         - github.com/prometheus/alertmanager

.promu.yml

@@ -1,7 +1,7 @@
 go:
     # Whenever the Go version is updated here,
     # .github/workflows/ci.yml and ui/app/Makefile should also be updated.
-    version: 1.26
+    version: 1.27
 repository:
     path: github.com/prometheus/alertmanager
 build:

AGENTS.md

@@ -6,7 +6,7 @@ Guidance for AI coding agents working in this repository. Keep this file concise
 
 Alertmanager handles alerts sent by clients such as Prometheus. It deduplicates, groups, routes, silences, and inhibits alerts, and dispatches them to receiver integrations (email, PagerDuty, Slack, webhook, etc.).
 
-- Language: Go (see `go.mod` for the required version, currently `go 1.25`).
+- Language: Go (see `go.mod` for the required version, currently `go 1.26`).
 - Frontend (legacy): Elm app under `ui/app/` (Node version pinned in `.nvmrc`).
 - Frontend (new): React + TypeScript + Mantine under `ui/mantine-ui/`.
 - API: OpenAPI v2 spec in `api/v2/openapi.yaml`; Go server/client/models are generated via `scripts/swagger.sh`.

Makefile

@@ -14,6 +14,8 @@
 # Needs to be defined before including Makefile.common to auto-generate targets
 DOCKER_ARCHS ?= amd64 armv7 arm64 ppc64le s390x
 
+GOLANGCI_LINT_VERSION := v2.13.1
+
 include Makefile.common
 
 FRONTEND_DIR             = $(BIN_DIR)/ui/app

api/v2/api_test.go

@@ -160,8 +160,6 @@ func TestGetSilencesHandler(t *testing.T) {
 	}
 }
 
-func boolPtr(b bool) *bool { return &b }
-
 func TestGetSilencesHandlerStateFilter(t *testing.T) {
 	now := timestamppb.Now()
 	silences := newSilences(t)
@@ -228,23 +226,23 @@ func TestGetSilencesHandlerStateFilter(t *testing.T) {
 	}
 
 	// No filter params (all true) - all three states returned.
-	require.Len(t, callHandler(boolPtr(true), boolPtr(true), boolPtr(true)), 3)
+	require.Len(t, callHandler(new(true), new(true), new(true)), 3)
 
 	// active=false - active silences excluded.
-	got := stateSet(callHandler(boolPtr(false), boolPtr(true), boolPtr(true)))
+	got := stateSet(callHandler(new(false), new(true), new(true)))
 	require.False(t, got["active"])
 	require.True(t, got["expired"] || got["pending"])
 
 	// expired=false - expired silences excluded.
-	got = stateSet(callHandler(boolPtr(true), boolPtr(false), boolPtr(true)))
+	got = stateSet(callHandler(new(true), new(false), new(true)))
 	require.False(t, got["expired"])
 
 	// pending=false - pending silences excluded.
-	got = stateSet(callHandler(boolPtr(true), boolPtr(true), boolPtr(false)))
+	got = stateSet(callHandler(new(true), new(true), new(false)))
 	require.False(t, got["pending"])
 
 	// all false - empty result.
-	require.Empty(t, callHandler(boolPtr(false), boolPtr(false), boolPtr(false)))
+	require.Empty(t, callHandler(new(false), new(false), new(false)))
 }
 
 func TestDeleteSilenceHandler(t *testing.T) {

cli/silence_import.go

@@ -62,8 +62,7 @@ func addSilenceWorker(ctx context.Context, sclient silence.ClientService, silenc
 		sid := s.ID
 		params := silence.NewPostSilencesParams().WithContext(ctx).WithSilence(s)
 		postOk, err := sclient.PostSilences(params)
-		var e *silence.PostSilencesNotFound
-		if errors.As(err, &e) {
+		if _, ok := errors.AsType[*silence.PostSilencesNotFound](err); ok {
 			// silence doesn't exists yet, retry to create as a new one
 			params.Silence.ID = ""
 			postOk, err = sclient.PostSilences(params)

cluster/tls_transport_test.go

@@ -166,7 +166,7 @@ func TestWriteTo(t *testing.T) {
 
 	from := fmt.Sprintf("%s:%d", t1.bindAddr, t1.GetAutoBindPort())
 	to := fmt.Sprintf("%s:%d", t2.bindAddr, t2.GetAutoBindPort())
-	sent := []byte(("test packet"))
+	sent := []byte("test packet")
 	_, err := t1.WriteTo(sent, to)
 	require.NoError(t, err)
 	packet := <-t2.PacketCh()
@@ -186,7 +186,7 @@ func BenchmarkWriteTo(b *testing.B) {
 	b.ResetTimer()
 	from := fmt.Sprintf("%s:%d", t1.bindAddr, t1.GetAutoBindPort())
 	to := fmt.Sprintf("%s:%d", t2.bindAddr, t2.GetAutoBindPort())
-	sent := []byte(("test packet"))
+	sent := []byte("test packet")
 
 	_, err := t1.WriteTo(sent, to)
 	require.NoError(b, err)
@@ -218,7 +218,7 @@ func TestDialTimeout(t *testing.T) {
 		to = <-t2.StreamCh()
 	})
 
-	sent := []byte(("test stream"))
+	sent := []byte("test stream")
 	m, err := from.Write(sent)
 	require.NoError(t, err)
 	require.Positive(t, m)

config/notifiers_test.go

@@ -383,7 +383,7 @@ fields:
 		{
 			Title: "first",
 			Value: "hello",
-			Short: newBoolPointer(true),
+			Short: new(true),
 		},
 		{
 			Title: "second",
@@ -393,7 +393,7 @@ fields:
 		{
 			Title: "third",
 			Value: "slack field test",
-			Short: newBoolPointer(false),
+			Short: new(false),
 		},
 	}
 
@@ -556,10 +556,6 @@ http_config:
 	}
 }
 
-func newBoolPointer(b bool) *bool {
-	return &b
-}
-
 func TestEmailConfig_UnmarshalYAML(t *testing.T) {
 	testConfig := []struct {
 		name     string