From ded0d4a9694a2f01cccdf077c74cc6923fc3cf19 Mon Sep 17 00:00:00 2001
From: Owen Diehl <ow.diehl@gmail.com>
Date: Wed, 24 Feb 2021 11:15:39 -0500
Subject: [PATCH] ability to split routes between AM & Grafana

---
 pkg/api/alertmanager.go            |  12 ++-
 pkg/validation/alertconfig.go      |  38 ++++++++-
 pkg/validation/alertconfig_test.go | 127 +++++++++++++++++++++++++++++
 3 files changed, 170 insertions(+), 7 deletions(-)

diff --git a/pkg/api/alertmanager.go b/pkg/api/alertmanager.go
index 581c59614b7..5177aeea43c 100644
--- a/pkg/api/alertmanager.go
+++ b/pkg/api/alertmanager.go
@@ -183,8 +183,8 @@ type GrafanaReceiver models.CreateAlertNotificationCommand
 type ReceiverType int
 
 const (
-	GrafanaManagedReceiver ReceiverType = iota
-	AMReceiver
+	GrafanaReceiverType ReceiverType = iota
+	AlertmanagerReceiverType
 )
 
 type ApiReceiver struct {
@@ -227,11 +227,17 @@ func (r *ApiReceiver) UnmarshalJSON(b []byte) error {
 		}
 
 	}
-
 	return nil
 
 }
 
+func (r *ApiReceiver) Type() ReceiverType {
+	if len(r.GrafanaReceivers.GrafanaManagedReceivers) > 0 {
+		return GrafanaReceiverType
+	}
+	return AlertmanagerReceiverType
+}
+
 type GrafanaReceivers struct {
 	GrafanaManagedReceivers []*GrafanaReceiver `yaml:"grafana_managed_receiver_configs,omitempty" json:"grafana_managed_receiver_configs,omitempty"`
 }
diff --git a/pkg/validation/alertconfig.go b/pkg/validation/alertconfig.go
index 35f1fd5d3d5..1b73a722f40 100644
--- a/pkg/validation/alertconfig.go
+++ b/pkg/validation/alertconfig.go
@@ -1,6 +1,8 @@
 package validation
 
 import (
+	"fmt"
+
 	"github.com/grafana/alerting-api/pkg/api"
 	"github.com/prometheus/alertmanager/config"
 )
@@ -20,10 +22,38 @@ type GrafanaAlertingConfig struct {
 // }
 
 // Routing trees must either contain only Grafana Managed receiver types or AlertManager receiver types
-// func SplitRoutes(routes []*config.Route, receivers map[string]*api.ApiReceiver) (gRoutes, amRoutes []*config.Route, err error) {
-// 	for _, route := range routes {
-// 	}
-// }
+func SplitRoutes(routes []*config.Route, receivers map[string]api.ReceiverType) (gRoutes, amRoutes []*config.Route, err error) {
+	for _, route := range routes {
+		var grafanaCt, amCt int
+		for _, receiver := range allReceivers(route) {
+			t, ok := receivers[receiver]
+			if !ok {
+				return nil, nil, fmt.Errorf("unexpected receiver (%s) is undefined", receiver)
+			}
+
+			if t == api.GrafanaReceiverType {
+				grafanaCt++
+			} else {
+				amCt++
+			}
+
+		}
+
+		// TODO(owen-d): We may want to eventually support this, but short-circuiting for now
+		// to reduce routing tree complexity.
+		if grafanaCt > 0 && amCt > 0 {
+			return nil, nil, fmt.Errorf("cannot mix Grafana Managed receivers with Alertmanager receivers in the same (non-root) routing tree")
+		}
+
+		if grafanaCt > 0 {
+			gRoutes = append(gRoutes, route)
+		} else {
+			amRoutes = append(amRoutes, route)
+		}
+	}
+
+	return gRoutes, amRoutes, nil
+}
 
 func allReceivers(route *config.Route) (res []string) {
 	res = append(res, route.Receiver)
diff --git a/pkg/validation/alertconfig_test.go b/pkg/validation/alertconfig_test.go
index 48f4f624314..29f2d099e3c 100644
--- a/pkg/validation/alertconfig_test.go
+++ b/pkg/validation/alertconfig_test.go
@@ -3,6 +3,7 @@ package validation
 import (
 	"testing"
 
+	"github.com/grafana/alerting-api/pkg/api"
 	"github.com/prometheus/alertmanager/config"
 	"github.com/stretchr/testify/require"
 )
@@ -27,3 +28,129 @@ func Test_allReceivers(t *testing.T) {
 
 	require.Equal(t, []string{"foo", "bar", "bazz", "buzz"}, allReceivers(input))
 }
+
+func Test_Splitroutes(t *testing.T) {
+	receivers := map[string]api.ReceiverType{
+		"am":   api.AlertmanagerReceiverType,
+		"graf": api.GrafanaReceiverType,
+	}
+
+	for _, tc := range []struct {
+		desc              string
+		input             []*config.Route
+		receivers         map[string]api.ReceiverType
+		err               bool
+		gRoutes, amRoutes []*config.Route
+	}{
+		{
+			desc: "splits simple",
+			input: []*config.Route{
+				{
+					Receiver: "am",
+				},
+				{
+					Receiver: "graf",
+				},
+			},
+			err: false,
+			gRoutes: []*config.Route{
+				{
+					Receiver: "graf",
+				},
+			},
+			amRoutes: []*config.Route{
+				{
+					Receiver: "am",
+				},
+			},
+		},
+		{
+			desc: "splits nested",
+			input: []*config.Route{
+				{
+					Receiver: "am",
+					Routes: []*config.Route{
+						{
+							Receiver: "am",
+						},
+					},
+				},
+				{
+					Receiver: "graf",
+					Routes: []*config.Route{
+						{
+							Receiver: "graf",
+						},
+					},
+				},
+			},
+			err: false,
+			gRoutes: []*config.Route{
+				{
+					Receiver: "graf",
+					Routes: []*config.Route{
+						{
+							Receiver: "graf",
+						},
+					},
+				},
+			},
+			amRoutes: []*config.Route{
+				{
+					Receiver: "am",
+					Routes: []*config.Route{
+						{
+							Receiver: "am",
+						},
+					},
+				},
+			},
+		},
+		{
+			desc: "errors undefined receiver",
+			input: []*config.Route{
+				{
+					Receiver: "am",
+					Routes: []*config.Route{
+						{
+							Receiver: "unmentioned",
+						},
+					},
+				},
+			},
+			err: true,
+		},
+		{
+			desc: "errors mixed",
+			input: []*config.Route{
+				{
+					Receiver: "am",
+					Routes: []*config.Route{
+						{
+							Receiver: "graf",
+						},
+					},
+				},
+				{
+					Receiver: "graf",
+					Routes: []*config.Route{
+						{
+							Receiver: "graf",
+						},
+					},
+				},
+			},
+			err: true,
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			gRoutes, amRoutes, err := SplitRoutes(tc.input, receivers)
+			if tc.err {
+				require.Error(t, err)
+			} else {
+				require.Equal(t, tc.gRoutes, gRoutes)
+				require.Equal(t, tc.amRoutes, amRoutes)
+			}
+		})
+	}
+}