Alerting/allow empty receiver (#33962)

* simplifies yaml unmarshaling: PostableApiReceiver

* allow empty receiver type

* allows name only receivers (blackhole)

* better receiver type parsing

* linting

pkg/services/ngalert/api/forked_am.go

@@ -117,22 +117,16 @@ func (am *ForkedAMSvc) RoutePostAlertingConfig(ctx *models.ReqContext, body apim
 		return response.Error(400, err.Error(), nil)
 	}
 
-	backendType, err := backendType(ctx, am.DatasourceCache)
+	b, err := backendType(ctx, am.DatasourceCache)
 	if err != nil {
 		return response.Error(400, err.Error(), nil)
 	}
 
-	payloadType := body.AlertmanagerConfig.Type()
-
-	if backendType != payloadType {
+	if err := body.AlertmanagerConfig.ReceiverType().MatchesBackend(b); err != nil {
 		return response.Error(
 			400,
-			fmt.Sprintf(
-				"unexpected backend type (%v) vs payload type (%v)",
-				backendType,
-				payloadType,
-			),
-			nil,
+			"bad match",
+			err,
 		)
 	}
 

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

@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"reflect"
 
 	"github.com/grafana/grafana/pkg/api/dtos"
 	"github.com/grafana/grafana/pkg/models"
@@ -381,6 +382,8 @@ func (c *GettableApiAlertingConfig) validate() error {
 			hasGrafReceivers = true
 		case AlertmanagerReceiverType:
 			hasAMReceivers = true
+		default:
+			continue
 		}
 	}
 
@@ -398,19 +401,6 @@ func (c *GettableApiAlertingConfig) validate() error {
 	return nil
 }
 
-// Type requires validate has been called and just checks the first receiver type
-func (c *GettableApiAlertingConfig) Type() (backend Backend) {
-	for _, r := range c.Receivers {
-		switch r.Type() {
-		case GrafanaReceiverType:
-			return GrafanaBackend
-		case AlertmanagerReceiverType:
-			return AlertmanagerBackend
-		}
-	}
-	return
-}
-
 // Config is the top-level configuration for Alertmanager's config files.
 type Config struct {
 	Global       *config.GlobalConfig  `yaml:"global,omitempty" json:"global,omitempty"`
@@ -448,6 +438,8 @@ func (c *PostableApiAlertingConfig) validate() error {
 			hasGrafReceivers = true
 		case AlertmanagerReceiverType:
 			hasAMReceivers = true
+		default:
+			continue
 		}
 	}
 
@@ -466,22 +458,26 @@ func (c *PostableApiAlertingConfig) validate() error {
 }
 
 // Type requires validate has been called and just checks the first receiver type
-func (c *PostableApiAlertingConfig) Type() (backend Backend) {
+func (c *PostableApiAlertingConfig) ReceiverType() ReceiverType {
 	for _, r := range c.Receivers {
 		switch r.Type() {
 		case GrafanaReceiverType:
-			return GrafanaBackend
+			return GrafanaReceiverType
 		case AlertmanagerReceiverType:
-			return AlertmanagerBackend
+			return AlertmanagerReceiverType
+		default:
+			continue
 		}
 	}
-	return
+	return EmptyReceiverType
 }
 
 // AllReceivers will recursively walk a routing tree and return a list of all the
 // referenced receiver names.
 func AllReceivers(route *config.Route) (res []string) {
-	res = append(res, route.Receiver)
+	if route.Receiver != "" {
+		res = append(res, route.Receiver)
+	}
 	for _, subRoute := range route.Routes {
 		res = append(res, AllReceivers(subRoute)...)
 	}
@@ -494,10 +490,52 @@ type PostableGrafanaReceiver models.CreateAlertNotificationCommand
 type ReceiverType int
 
 const (
-	GrafanaReceiverType ReceiverType = iota
+	GrafanaReceiverType ReceiverType = 1 << iota
 	AlertmanagerReceiverType
+	EmptyReceiverType = GrafanaReceiverType | AlertmanagerReceiverType
 )
 
+func (r ReceiverType) String() string {
+	switch r {
+	case GrafanaReceiverType:
+		return "grafana"
+	case AlertmanagerReceiverType:
+		return "alertmanager"
+	case EmptyReceiverType:
+		return "empty"
+	default:
+		return "unknown"
+	}
+}
+
+// Can determines whether a receiver type can implement another receiver type.
+// This is useful as receivers with just names but no contact points
+// are valid in all backends.
+func (r ReceiverType) Can(other ReceiverType) bool { return r&other != 0 }
+
+// MatchesBackend determines if a config payload can be sent to a particular backend type
+func (r ReceiverType) MatchesBackend(backend Backend) error {
+	msg := func(backend Backend, receiver ReceiverType) error {
+		return fmt.Errorf(
+			"unexpected backend type (%s) for receiver type (%s)",
+			backend.String(),
+			receiver.String(),
+		)
+	}
+	var ok bool
+	switch backend {
+	case GrafanaBackend:
+		ok = r.Can(GrafanaReceiverType)
+	case AlertmanagerBackend:
+		ok = r.Can(AlertmanagerReceiverType)
+	default:
+	}
+	if !ok {
+		return msg(backend, r)
+	}
+	return nil
+}
+
 type GettableApiReceiver struct {
 	config.Receiver          `yaml:",inline"`
 	GettableGrafanaReceivers `yaml:",inline"`
@@ -554,25 +592,14 @@ type PostableApiReceiver struct {
 }
 
 func (r *PostableApiReceiver) UnmarshalYAML(unmarshal func(interface{}) error) error {
-	var grafanaReceivers PostableGrafanaReceivers
-	if err := unmarshal(&grafanaReceivers); err != nil {
+	if err := unmarshal(&r.PostableGrafanaReceivers); err != nil {
 		return err
 	}
-	r.PostableGrafanaReceivers = grafanaReceivers
 
-	var cfg config.Receiver
-	if err := unmarshal(&cfg); err != nil {
+	if err := unmarshal(&r.Receiver); err != nil {
 		return err
 	}
-	r.Name = cfg.Name
-	r.EmailConfigs = cfg.EmailConfigs
-	r.PagerdutyConfigs = cfg.PagerdutyConfigs
-	r.SlackConfigs = cfg.SlackConfigs
-	r.WebhookConfigs = cfg.WebhookConfigs
-	r.OpsGenieConfigs = cfg.OpsGenieConfigs
-	r.WechatConfigs = cfg.WechatConfigs
-	r.PushoverConfigs = cfg.PushoverConfigs
-	r.VictorOpsConfigs = cfg.VictorOpsConfigs
+
 	return nil
 }
 
@@ -617,6 +644,13 @@ func (r *PostableApiReceiver) Type() ReceiverType {
 	if len(r.PostableGrafanaReceivers.GrafanaManagedReceivers) > 0 {
 		return GrafanaReceiverType
 	}
+
+	cpy := r.Receiver
+	cpy.Name = ""
+	if reflect.ValueOf(cpy).IsZero() {
+		return EmptyReceiverType
+	}
+
 	return AlertmanagerReceiverType
 }
 

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

@@ -69,6 +69,50 @@ func Test_ApiReceiver_Marshaling(t *testing.T) {
 	}
 }
 
+func Test_APIReceiverType(t *testing.T) {
+	for _, tc := range []struct {
+		desc     string
+		input    PostableApiReceiver
+		expected ReceiverType
+	}{
+		{
+			desc: "empty",
+			input: PostableApiReceiver{
+				Receiver: config.Receiver{
+					Name: "foo",
+				},
+			},
+			expected: EmptyReceiverType,
+		},
+		{
+			desc: "am",
+			input: PostableApiReceiver{
+				Receiver: config.Receiver{
+					Name:         "foo",
+					EmailConfigs: []*config.EmailConfig{{}},
+				},
+			},
+			expected: AlertmanagerReceiverType,
+		},
+		{
+			desc: "graf",
+			input: PostableApiReceiver{
+				Receiver: config.Receiver{
+					Name: "foo",
+				},
+				PostableGrafanaReceivers: PostableGrafanaReceivers{
+					GrafanaManagedReceivers: []*PostableGrafanaReceiver{{}},
+				},
+			},
+			expected: GrafanaReceiverType,
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			require.Equal(t, tc.expected, tc.input.Type())
+		})
+	}
+}
+
 func Test_AllReceivers(t *testing.T) {
 	input := &config.Route{
 		Receiver: "foo",
@@ -88,6 +132,10 @@ func Test_AllReceivers(t *testing.T) {
 	}
 
 	require.Equal(t, []string{"foo", "bar", "bazz", "buzz"}, AllReceivers(input))
+
+	// test empty
+	var empty []string
+	require.Equal(t, empty, AllReceivers(&config.Route{}))
 }
 
 func Test_ApiAlertingConfig_Marshaling(t *testing.T) {
@@ -405,3 +453,113 @@ func Test_GettableUserConfigRoundtrip(t *testing.T) {
 	require.Nil(t, err)
 	require.Equal(t, string(yamlEncoded), string(out))
 }
+
+func Test_ReceiverCompatibility(t *testing.T) {
+	for _, tc := range []struct {
+		desc     string
+		a, b     ReceiverType
+		expected bool
+	}{
+		{
+			desc:     "grafana=grafana",
+			a:        GrafanaReceiverType,
+			b:        GrafanaReceiverType,
+			expected: true,
+		},
+		{
+			desc:     "am=am",
+			a:        AlertmanagerReceiverType,
+			b:        AlertmanagerReceiverType,
+			expected: true,
+		},
+		{
+			desc:     "empty=grafana",
+			a:        EmptyReceiverType,
+			b:        AlertmanagerReceiverType,
+			expected: true,
+		},
+		{
+			desc:     "empty=am",
+			a:        EmptyReceiverType,
+			b:        AlertmanagerReceiverType,
+			expected: true,
+		},
+		{
+			desc:     "empty=empty",
+			a:        EmptyReceiverType,
+			b:        EmptyReceiverType,
+			expected: true,
+		},
+		{
+			desc:     "graf!=am",
+			a:        GrafanaReceiverType,
+			b:        AlertmanagerReceiverType,
+			expected: false,
+		},
+		{
+			desc:     "am!=graf",
+			a:        AlertmanagerReceiverType,
+			b:        GrafanaReceiverType,
+			expected: false,
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			require.Equal(t, tc.expected, tc.a.Can(tc.b))
+		})
+	}
+}
+
+func Test_ReceiverMatchesBackend(t *testing.T) {
+	for _, tc := range []struct {
+		desc string
+		rec  ReceiverType
+		b    Backend
+		err  bool
+	}{
+		{
+			desc: "graf=graf",
+			rec:  GrafanaReceiverType,
+			b:    GrafanaBackend,
+			err:  false,
+		},
+		{
+			desc: "empty=graf",
+			rec:  EmptyReceiverType,
+			b:    GrafanaBackend,
+			err:  false,
+		},
+		{
+			desc: "am=am",
+			rec:  AlertmanagerReceiverType,
+			b:    AlertmanagerBackend,
+			err:  false,
+		},
+		{
+			desc: "empty=am",
+			rec:  EmptyReceiverType,
+			b:    AlertmanagerBackend,
+			err:  false,
+		},
+		{
+			desc: "graf!=am",
+			rec:  GrafanaReceiverType,
+			b:    AlertmanagerBackend,
+			err:  true,
+		},
+		{
+			desc: "am!=ruler",
+			rec:  GrafanaReceiverType,
+			b:    LoTexRulerBackend,
+			err:  true,
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			err := tc.rec.MatchesBackend(tc.b)
+			if tc.err {
+				require.NotNil(t, err)
+			} else {
+				require.Nil(t, err)
+			}
+		})
+	}
+}