feat(ruler): support alert relabeling (#6220)

docs/sources/configuration/_index.md

@@ -677,6 +677,10 @@ alertmanager_client:
 # CLI flag: -ruler.alertmanager-use-v2
 [enable_alertmanager_v2: <boolean> | default = false]
 
+# List of alert relabel configs
+alert_relabel_configs:
+  [- <relabel_config> ...]
+
 # Capacity of the queue for notifications to be sent to the Alertmanager.
 # CLI flag: -ruler.notification-queue-capacity
 [notification_queue_capacity: <int> | default = 10000]

pkg/ruler/base/notifier.go

@@ -134,6 +134,7 @@ func buildNotifierConfig(rulerConfig *Config) (*config.Config, error) {
 			ExternalLabels: rulerConfig.ExternalLabels,
 		},
 		AlertingConfig: config.AlertingConfig{
+			AlertRelabelConfigs: rulerConfig.AlertRelabelConfigs,
 			AlertmanagerConfigs: amConfigs,
 		},
 	}

pkg/ruler/base/notifier_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/prometheus/prometheus/discovery"
 	"github.com/prometheus/prometheus/discovery/dns"
 	"github.com/prometheus/prometheus/model/labels"
+	"github.com/prometheus/prometheus/model/relabel"
 	"github.com/stretchr/testify/require"
 
 	"github.com/grafana/loki/pkg/util"
@@ -325,6 +326,54 @@ func TestBuildNotifierConfig(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "with alert relabel config",
+			cfg: &Config{
+				AlertmanagerURL: "http://alertmanager.default.svc.cluster.local/alertmanager",
+				ExternalLabels: []labels.Label{
+					{Name: "region", Value: "us-east-1"},
+				},
+				AlertRelabelConfigs: []*relabel.Config{
+					{
+						SourceLabels: model.LabelNames{"severity"},
+						Regex:        relabel.MustNewRegexp("high"),
+						TargetLabel:  "priority",
+						Replacement:  "p1",
+					},
+				},
+			},
+			ncfg: &config.Config{
+				AlertingConfig: config.AlertingConfig{
+					AlertmanagerConfigs: []*config.AlertmanagerConfig{
+						{
+							APIVersion: "v1",
+							Scheme:     "http",
+							PathPrefix: "/alertmanager",
+							ServiceDiscoveryConfigs: discovery.Configs{
+								discovery.StaticConfig{
+									{
+										Targets: []model.LabelSet{{"__address__": "alertmanager.default.svc.cluster.local"}},
+									},
+								},
+							},
+						},
+					},
+					AlertRelabelConfigs: []*relabel.Config{
+						{
+							SourceLabels: model.LabelNames{"severity"},
+							Regex:        relabel.MustNewRegexp("high"),
+							TargetLabel:  "priority",
+							Replacement:  "p1",
+						},
+					},
+				},
+				GlobalConfig: config.GlobalConfig{
+					ExternalLabels: []labels.Label{
+						{Name: "region", Value: "us-east-1"},
+					},
+				},
+			},
+		},
 	}
 
 	for _, tt := range tests {

pkg/ruler/base/ruler.go

@@ -24,6 +24,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/prometheus/model/labels"
+	"github.com/prometheus/prometheus/model/relabel"
 	"github.com/prometheus/prometheus/model/rulefmt"
 	"github.com/prometheus/prometheus/notifier"
 	promRules "github.com/prometheus/prometheus/rules"
@@ -94,6 +95,8 @@ type Config struct {
 	AlertmanagerRefreshInterval time.Duration `yaml:"alertmanager_refresh_interval"`
 	// Enables the ruler notifier to use the Alertmananger V2 API.
 	AlertmanangerEnableV2API bool `yaml:"enable_alertmanager_v2"`
+	// Configuration for alert relabeling.
+	AlertRelabelConfigs []*relabel.Config `yaml:"alert_relabel_configs,omitempty"`
 	// Capacity of the queue for notifications to be sent to the Alertmanager.
 	NotificationQueueCapacity int `yaml:"notification_queue_capacity"`
 	// HTTP timeout duration when sending notifications to the Alertmanager.