Fix UTF-8 not allowed in Equal field for inhibition rules (#10780)

This commit fixes a bug where UTF-8 characters are not allowed in
the Equal field for inhibition rules, even when UTF-8 strict mode
is enabled.

This bug occurred because we forgot to override the validation in
model.LabelName. I have copied the same logic used for GroupBy with
GroupByStr, adding EqualStr.

We would like to upgrade prometheus/common in future and use the
validation there instead, but it presents challenges with downstream
projects like Mimir and Cortex where, at present, UTF-8 can be enabled
and disabled in separate components at the same time,
which is not supported in prometheus/common.

The tests for this fix can be found in grafana/prometheus-alertmanager#94
and grafana/alerting#271.

go.mod

@@ -66,7 +66,7 @@ require (
 	github.com/google/go-github/v57 v57.0.0
 	github.com/google/uuid v1.6.0
 	github.com/grafana-tools/sdk v0.0.0-20220919052116-6562121319fc
-	github.com/grafana/alerting v0.0.0-20250225150117-15e285d78df2
+	github.com/grafana/alerting v0.0.0-20250303095629-6fd0c494dfa3
 	github.com/grafana/regexp v0.0.0-20240607082908-2cb410fa05da
 	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/hashicorp/vault/api v1.15.0
@@ -325,7 +325,7 @@ replace github.com/opentracing-contrib/go-stdlib => github.com/grafana/opentraci
 replace github.com/opentracing-contrib/go-grpc => github.com/charleskorn/go-grpc v0.0.0-20231024023642-e9298576254f
 
 // Replacing prometheus/alertmanager with our fork.
-replace github.com/prometheus/alertmanager => github.com/grafana/prometheus-alertmanager v0.25.1-0.20250211112812-e32be5e2a455
+replace github.com/prometheus/alertmanager => github.com/grafana/prometheus-alertmanager v0.25.1-0.20250303091802-46a7be9c9432
 
 // Replacing with a fork commit based on v1.17.1 having cherry-picked the following PRs:
 // - https://github.com/grafana/franz-go/pull/1

go.sum

@@ -1270,8 +1270,8 @@ github.com/gosimple/slug v1.1.1 h1:fRu/digW+NMwBIP+RmviTK97Ho/bEj/C9swrCspN3D4=
 github.com/gosimple/slug v1.1.1/go.mod h1:ER78kgg1Mv0NQGlXiDe57DpCyfbNywXXZ9mIorhxAf0=
 github.com/grafana-tools/sdk v0.0.0-20220919052116-6562121319fc h1:PXZQA2WCxe85Tnn+WEvr8fDpfwibmEPgfgFEaC87G24=
 github.com/grafana-tools/sdk v0.0.0-20220919052116-6562121319fc/go.mod h1:AHHlOEv1+GGQ3ktHMlhuTUwo3zljV3QJbC0+8o2kn+4=
-github.com/grafana/alerting v0.0.0-20250225150117-15e285d78df2 h1:kESrzm0FcRVLmGIQCgl1MCwDGLH4sLzWphr7mcFdbfI=
-github.com/grafana/alerting v0.0.0-20250225150117-15e285d78df2/go.mod h1:hdGB3dSl8Ma9Rjo2YiAEAjMkZ5HiNJbNDqRKDefRZrM=
+github.com/grafana/alerting v0.0.0-20250303095629-6fd0c494dfa3 h1:otX6Lww40e6jEsc4AQBdYmgDsaryAZkBTdBvWUsnDxk=
+github.com/grafana/alerting v0.0.0-20250303095629-6fd0c494dfa3/go.mod h1:p5P86ajOwL2XPJN6+xu6QJUtO4DptdFiqJ35r3Ac4HY=
 github.com/grafana/dskit v0.0.0-20250303172748-fd4441b85237 h1:VZagYtPcmjgazfPAuWN7lER6mprG20r51+1eYPpATkw=
 github.com/grafana/dskit v0.0.0-20250303172748-fd4441b85237/go.mod h1:cu2zIOHhAgRaIDuECsERftSp1l7KHq1aX1jgihQCu0c=
 github.com/grafana/e2e v0.1.2-0.20240118170847-db90b84177fc h1:BW+LjKJDz0So5LI8UZfW5neWeKpSkWqhmGjQFzcFfLM=
@@ -1288,8 +1288,8 @@ github.com/grafana/mimir-prometheus v0.0.0-20250304035310-4c85ad035a73 h1:xojy4g
 github.com/grafana/mimir-prometheus v0.0.0-20250304035310-4c85ad035a73/go.mod h1:9SIFvqYMa125MSHK5SAEnOGLDikyUMk4tHUQjZtbhs8=
 github.com/grafana/opentracing-contrib-go-stdlib v0.0.0-20230509071955-f410e79da956 h1:em1oddjXL8c1tL0iFdtVtPloq2hRPen2MJQKoAWpxu0=
 github.com/grafana/opentracing-contrib-go-stdlib v0.0.0-20230509071955-f410e79da956/go.mod h1:qtI1ogk+2JhVPIXVc6q+NHziSmy2W5GbdQZFUHADCBU=
-github.com/grafana/prometheus-alertmanager v0.25.1-0.20250211112812-e32be5e2a455 h1:yidC1xzk4fedLZ/iXEqSJopkw3jPZPwoMqqzue4eFEA=
-github.com/grafana/prometheus-alertmanager v0.25.1-0.20250211112812-e32be5e2a455/go.mod h1:FGdGvhI40Dq+CTQaSzK9evuve774cgOUdGfVO04OXkw=
+github.com/grafana/prometheus-alertmanager v0.25.1-0.20250303091802-46a7be9c9432 h1:iLM/0h8BWb7/RPDzqphwFHE7tr5m5f1atwHquv8uWm8=
+github.com/grafana/prometheus-alertmanager v0.25.1-0.20250303091802-46a7be9c9432/go.mod h1:FGdGvhI40Dq+CTQaSzK9evuve774cgOUdGfVO04OXkw=
 github.com/grafana/pyroscope-go/godeltaprof v0.1.8 h1:iwOtYXeeVSAeYefJNaxDytgjKtUuKQbJqgAIjlnicKg=
 github.com/grafana/pyroscope-go/godeltaprof v0.1.8/go.mod h1:2+l7K7twW49Ct4wFluZD3tZ6e0SjanjcUUBPVD/UuGU=
 github.com/grafana/regexp v0.0.0-20240531075221-3685f1377d7b h1:oMAq12GxTpwo9jxbnG/M4F/HdpwbibTaVoxNA0NZprY=

integration/configs.go

@@ -64,6 +64,13 @@ receivers:
       - bar=baz
 receivers:
   - name: test
+inhibit_rules:
+  - source_matchers:
+    - baz=qux
+    target_matchers:
+    - qux=corge
+    equal:
+    - jorge
 `
 
 	mimirAlertmanagerUserUTF8ConfigYaml = `route:
@@ -75,6 +82,13 @@ receivers:
       - bar🙂=baz
 receivers:
   - name: test
+inhibit_rules:
+  - source_matchers:
+    - baz🙂=qux
+    target_matchers:
+    - qux🙂=corge
+    equal:
+    - jorge🙂
 `
 
 	mimirRulerUserConfigYaml = `groups: