Alerting: Support for Mimir configuration in Grafana Alertmanager (#106402)

pkg/services/ngalert/api/tooling/definitions/alertmanager.go

@@ -3,13 +3,17 @@ package definitions
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"time"
 
 	"github.com/go-openapi/strfmt"
+	alertingTemplates "github.com/grafana/alerting/templates"
 	amv2 "github.com/prometheus/alertmanager/api/v2/models"
 	"github.com/prometheus/alertmanager/config"
+	"github.com/prometheus/alertmanager/pkg/labels"
 	"github.com/prometheus/common/model"
+
 	"gopkg.in/yaml.v3"
 
 	"github.com/grafana/alerting/definition"
@@ -263,6 +267,7 @@ type (
 	PostableApiReceiver       = definition.PostableApiReceiver
 	PostableGrafanaReceivers  = definition.PostableGrafanaReceivers
 	ReceiverType              = definition.ReceiverType
+	MergeResult               = definition.MergeResult
 )
 
 const (
@@ -643,13 +648,82 @@ type DatasourceUIDReference struct {
 	DatasourceUID string
 }
 
+type ExtraConfiguration struct {
+	Identifier         string                    `yaml:"identifier" json:"identifier"`
+	MergeMatchers      config.Matchers           `yaml:"merge_matchers" json:"merge_matchers"`
+	TemplateFiles      map[string]string         `yaml:"template_files" json:"template_files"`
+	AlertmanagerConfig PostableApiAlertingConfig `yaml:"alertmanager_config" json:"alertmanager_config"`
+}
+
+func (c ExtraConfiguration) Validate() error {
+	if c.Identifier == "" {
+		return errors.New("identifier is required")
+	}
+	if len(c.MergeMatchers) == 0 {
+		return errors.New("at least one matcher is required")
+	}
+	for _, m := range c.MergeMatchers {
+		if m.Type != labels.MatchEqual {
+			return errors.New("only matchers with type equal are supported")
+		}
+	}
+	err := c.AlertmanagerConfig.Validate()
+	if err != nil {
+		return fmt.Errorf("invalid alertmanager configuration: %w", err)
+	}
+	return nil
+}
+
 // swagger:model
 type PostableUserConfig struct {
 	TemplateFiles      map[string]string         `yaml:"template_files" json:"template_files"`
 	AlertmanagerConfig PostableApiAlertingConfig `yaml:"alertmanager_config" json:"alertmanager_config"`
+	ExtraConfigs       []ExtraConfiguration      `yaml:"extra_config,omitempty" json:"extra_config,omitempty"`
 	amSimple           map[string]interface{}    `yaml:"-" json:"-"`
 }
 
+func (c *PostableUserConfig) GetMergedAlertmanagerConfig() (MergeResult, error) {
+	if len(c.ExtraConfigs) == 0 {
+		return MergeResult{
+			Config: c.AlertmanagerConfig,
+		}, nil
+	}
+	// support only one config for now
+	mimirCfg := c.ExtraConfigs[0]
+	opts := definition.MergeOpts{
+		DedupSuffix:     mimirCfg.Identifier,
+		SubtreeMatchers: mimirCfg.MergeMatchers,
+	}
+	if err := opts.Validate(); err != nil {
+		return MergeResult{}, fmt.Errorf("invalid merge options: %w", err)
+	}
+	return definition.Merge(c.AlertmanagerConfig, mimirCfg.AlertmanagerConfig, opts) // for now support only the first extra config
+}
+
+// GetMergedTemplateDefinitions converts the given PostableUserConfig's TemplateFiles to a slice of TemplateDefinitions.
+func (c *PostableUserConfig) GetMergedTemplateDefinitions() []alertingTemplates.TemplateDefinition {
+	out := make([]alertingTemplates.TemplateDefinition, 0, len(c.TemplateFiles))
+	for name, tmpl := range c.TemplateFiles {
+		out = append(out, alertingTemplates.TemplateDefinition{
+			Name:     name,
+			Template: tmpl,
+			Kind:     alertingTemplates.GrafanaKind,
+		})
+	}
+	if len(c.ExtraConfigs) == 0 {
+		return out
+	}
+	// support only one config for now
+	for name, tmpl := range c.ExtraConfigs[0].TemplateFiles {
+		out = append(out, alertingTemplates.TemplateDefinition{
+			Name:     name,
+			Template: tmpl,
+			Kind:     alertingTemplates.MimirKind,
+		})
+	}
+	return out
+}
+
 func (c *PostableUserConfig) UnmarshalJSON(b []byte) error {
 	type plain PostableUserConfig
 	if err := json.Unmarshal(b, (*plain)(c)); err != nil {
@@ -661,6 +735,15 @@ func (c *PostableUserConfig) UnmarshalJSON(b []byte) error {
 		return err
 	}
 
+	if len(c.ExtraConfigs) > 1 {
+		return errors.New("only one extra config is supported")
+	}
+	for _, extraConfig := range c.ExtraConfigs {
+		if err := extraConfig.Validate(); err != nil {
+			return fmt.Errorf("extra configuration is invalid: %w", err)
+		}
+	}
+
 	type intermediate struct {
 		AlertmanagerConfig map[string]interface{} `yaml:"alertmanager_config" json:"alertmanager_config"`
 	}