api: Expose mesh status (#644)

* api: Expose mesh status

The weaveworks mesh package reveals information about the current status
of the mesh network between alertmanager instances. This commit exposes
the current address and connection status of each instance connected to
the targeted alertmanager instance via the /status API endpoint.

* api: Replace LocalConnectionStatus with PeerStatus

Now meshStatus contains all peers (Name, NickName, UID) of the network.
Additionally adding Name and Nickname of current target to toplevel of
meshNetwork object.

api/api.go

@@ -34,6 +34,7 @@ import (
 	"github.com/prometheus/alertmanager/silence"
 	"github.com/prometheus/alertmanager/silence/silencepb"
 	"github.com/prometheus/alertmanager/types"
+	"github.com/weaveworks/mesh"
 )
 
 var (
@@ -77,6 +78,7 @@ type API struct {
 	configJSON     config.Config
 	resolveTimeout time.Duration
 	uptime         time.Time
+	mrouter        *mesh.Router
 
 	groups func() dispatch.AlertOverview
 
@@ -86,13 +88,14 @@ type API struct {
 }
 
 // New returns a new API.
-func New(alerts provider.Alerts, silences *silence.Silences, gf func() dispatch.AlertOverview) *API {
+func New(alerts provider.Alerts, silences *silence.Silences, gf func() dispatch.AlertOverview, router *mesh.Router) *API {
 	return &API{
 		context:  route.Context,
 		alerts:   alerts,
 		silences: silences,
 		groups:   gf,
 		uptime:   time.Now(),
+		mrouter:  router,
 	}
 }
 
@@ -169,6 +172,7 @@ func (api *API) status(w http.ResponseWriter, req *http.Request) {
 		ConfigJSON  config.Config     `json:"configJSON"`
 		VersionInfo map[string]string `json:"versionInfo"`
 		Uptime      time.Time         `json:"uptime"`
+		MeshStatus  meshStatus        `json:"meshStatus"`
 	}{
 		Config:     api.config,
 		ConfigJSON: api.configJSON,
@@ -180,7 +184,8 @@ func (api *API) status(w http.ResponseWriter, req *http.Request) {
 			"buildDate": version.BuildDate,
 			"goVersion": version.GoVersion,
 		},
-		Uptime: api.uptime,
+		Uptime:     api.uptime,
+		MeshStatus: getMeshStatus(api),
 	}
 
 	api.mtx.RUnlock()
@@ -188,6 +193,37 @@ func (api *API) status(w http.ResponseWriter, req *http.Request) {
 	respond(w, status)
 }
 
+type meshStatus struct {
+	Name     string       `json:"name"`
+	NickName string       `json:"nickName"`
+	Peers    []peerStatus `json:"peers"`
+}
+
+type peerStatus struct {
+	Name     string `json:"name"`     // e.g. "00:00:00:00:00:01"
+	NickName string `json:"nickName"` // e.g. "a"
+	UID      uint64 `json:"uid"`      // e.g. "14015114173033265000"
+}
+
+func getMeshStatus(api *API) meshStatus {
+	status := mesh.NewStatus(api.mrouter)
+	strippedStatus := meshStatus{
+		Name:     status.Name,
+		NickName: status.NickName,
+		Peers:    make([]peerStatus, len(status.Peers)),
+	}
+
+	for i := 0; i < len(status.Peers); i++ {
+		strippedStatus.Peers[i] = peerStatus{
+			Name:     status.Peers[i].Name,
+			NickName: status.Peers[i].NickName,
+			UID:      uint64(status.Peers[i].UID),
+		}
+	}
+
+	return strippedStatus
+}
+
 func (api *API) alertGroups(w http.ResponseWriter, req *http.Request) {
 	respond(w, api.groups())
 }

cmd/alertmanager/main.go

@@ -180,7 +180,7 @@ func main() {
 
 	apiv := api.New(alerts, silences, func() dispatch.AlertOverview {
 		return disp.Groups()
-	})
+	}, mrouter)
 
 	amURL, err := extURL(*listenAddress, *externalURL)
 	if err != nil {