api: Combine v1 and v2 into generic api

Instead of cmd/alertmanager/main.go instantiating and starting both api
v1 and v2, delegate that work to a generic api combining the two.

Signed-off-by: Max Leonard Inden <[email protected]>

api/api.go

@@ -0,0 +1,96 @@
+// Copyright 2019 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package api
+
+import (
+	"net/http"
+	"time"
+
+	apiv1 "github.com/prometheus/alertmanager/api/v1"
+	apiv2 "github.com/prometheus/alertmanager/api/v2"
+	"github.com/prometheus/alertmanager/cluster"
+	"github.com/prometheus/alertmanager/config"
+	"github.com/prometheus/alertmanager/provider"
+	"github.com/prometheus/alertmanager/silence"
+	"github.com/prometheus/alertmanager/types"
+	"github.com/prometheus/common/model"
+	"github.com/prometheus/common/route"
+
+	"github.com/go-kit/kit/log"
+)
+
+// API represents all APIs of Alertmanager.
+type API struct {
+	v1 *apiv1.API
+	v2 *apiv2.API
+}
+
+// New creates a new API object combining all API versions.
+func New(
+	alerts provider.Alerts,
+	silences *silence.Silences,
+	sf func(model.Fingerprint) types.AlertStatus,
+	peer *cluster.Peer,
+	l log.Logger,
+) (*API, error) {
+	v1 := apiv1.New(
+		alerts,
+		silences,
+		sf,
+		peer,
+		log.With(l, "version", "v1"),
+	)
+
+	v2, err := apiv2.NewAPI(
+		alerts,
+		sf,
+		silences,
+		peer,
+		log.With(l, "version", "v2"),
+	)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &API{
+		v1: v1,
+		v2: v2,
+	}, nil
+}
+
+// Register all APIs with the given router and return a mux.
+func (api *API) Register(r *route.Router, routePrefix string) *http.ServeMux {
+	api.v1.Register(r.WithPrefix("/api/v1"))
+
+	mux := http.NewServeMux()
+	mux.Handle("/", r)
+
+	apiPrefix := ""
+	if routePrefix != "/" {
+		apiPrefix = routePrefix
+	}
+	mux.Handle(apiPrefix+"/api/v2/", http.StripPrefix(apiPrefix+"/api/v2", api.v2.Handler))
+
+	return mux
+}
+
+// Update config and resolve timeout of each API.
+func (api *API) Update(cfg *config.Config, resolveTimeout time.Duration) error {
+	if err := api.v1.Update(cfg, resolveTimeout); err != nil {
+		return err
+	}
+
+	return api.v2.Update(cfg, resolveTimeout)
+}

cmd/alertmanager/main.go

@@ -40,8 +40,7 @@ import (
 	"github.com/prometheus/common/version"
 	"gopkg.in/alecthomas/kingpin.v2"
 
-	apiv1 "github.com/prometheus/alertmanager/api/v1"
-	apiv2 "github.com/prometheus/alertmanager/api/v2"
+	"github.com/prometheus/alertmanager/api"
 	"github.com/prometheus/alertmanager/cluster"
 	"github.com/prometheus/alertmanager/config"
 	"github.com/prometheus/alertmanager/dispatch"
@@ -292,23 +291,16 @@ func run() int {
 	)
 	defer disp.Stop()
 
-	apiV1 := apiv1.New(
+	api, err := api.New(
 		alerts,
 		silences,
 		marker.Status,
 		peer,
-		log.With(logger, "component", "api/v1"),
+		log.With(logger, "component", "api"),
 	)
 
-	apiV2, err := apiv2.NewAPI(
-		alerts,
-		marker.Status,
-		silences,
-		peer,
-		log.With(logger, "component", "api/v2"),
-	)
 	if err != nil {
-		level.Error(logger).Log("err", fmt.Errorf("failed to create API v2: %v", err.Error()))
+		level.Error(logger).Log("err", fmt.Errorf("failed to create API: %v", err.Error()))
 		return 1
 	}
 
@@ -350,12 +342,7 @@ func run() int {
 
 		hash = md5HashAsMetricValue(plainCfg)
 
-		err = apiV1.Update(conf, time.Duration(conf.Global.ResolveTimeout))
-		if err != nil {
-			return err
-		}
-
-		err = apiV2.Update(conf, time.Duration(conf.Global.ResolveTimeout))
+		err = api.Update(conf, time.Duration(conf.Global.ResolveTimeout))
 		if err != nil {
 			return err
 		}
@@ -410,16 +397,7 @@ func run() int {
 
 	ui.Register(router, webReload, logger)
 
-	apiV1.Register(router.WithPrefix("/api/v1"))
-
-	mux := http.NewServeMux()
-	mux.Handle("/", router)
-
-	apiPrefix := ""
-	if *routePrefix != "/" {
-		apiPrefix = *routePrefix
-	}
-	mux.Handle(apiPrefix+"/api/v2/", http.StripPrefix(apiPrefix+"/api/v2", apiV2.Handler))
+	mux := api.Register(router, *routePrefix)
 
 	srv := http.Server{Addr: *listenAddress, Handler: mux}
 	srvc := make(chan struct{})