added health check endpoints

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/go-redis/redis/v8 v8.11.4
 	github.com/gorilla/mux v1.8.0
 	github.com/prometheus/client_golang v1.12.1
+	github.com/tevino/abool/v2 v2.0.1
 )
 
 require (

go.sum

@@ -208,6 +208,8 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
+github.com/tevino/abool/v2 v2.0.1 h1:OF7FC5V5z3yAWyixbc32ecEzrgAJCsPkVOsPM2qoZPI=
+github.com/tevino/abool/v2 v2.0.1/go.mod h1:+Lmlqk6bHDWHqN1cbxqhwEAwMPXgc8I1SDEamtseuXY=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=

main.go

@@ -20,6 +20,7 @@ import (
 	"github.com/go-redis/redis/v8"
 	"github.com/gorilla/mux"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/tevino/abool/v2"
 )
 
 const (
@@ -220,6 +221,7 @@ type GlobalBackfeedManager struct {
 	BackfeedRedis *redis.ClusterClient
 	LegacyRedis   *redis.Client
 	Lock          sync.RWMutex
+	Populated     *abool.AtomicBool
 }
 
 func (that *GlobalBackfeedManager) RefreshFeeds() error {
@@ -330,6 +332,9 @@ func (that *GlobalBackfeedManager) RefreshFeeds() error {
 		<-projectBackfeedManager.Done
 		log.Printf("removed project: %s", project)
 	}
+	if !that.Populated.IsSet() {
+		that.Populated.Set()
+	}
 	return nil
 }
 
@@ -394,7 +399,7 @@ func (that *GlobalBackfeedManager) GetFeed(slug string) *ProjectBackfeedManager
 	return projectBackfeedManager
 }
 
-func (that *GlobalBackfeedManager) Handle(res http.ResponseWriter, req *http.Request) {
+func (that *GlobalBackfeedManager) HandleLegacy(res http.ResponseWriter, req *http.Request) {
 	defer req.Body.Close()
 
 	vars := mux.Vars(req)
@@ -454,7 +459,32 @@ func (that *GlobalBackfeedManager) Handle(res http.ResponseWriter, req *http.Req
 	return
 }
 
+func (that *GlobalBackfeedManager) HandleHealth(res http.ResponseWriter, req *http.Request) {
+	if that.Populated.IsNotSet() {
+		WriteResponse(res, http.StatusServiceUnavailable, fmt.Errorf("%s", "backfeed not populated"))
+		return
+	}
+	err := that.LegacyRedis.Ping(req.Context()).Err()
+	if err != nil {
+		WriteResponse(res, http.StatusInternalServerError, fmt.Errorf("failed to ping legacy redis: %s", err))
+		return
+	}
+	err = that.BackfeedRedis.ForEachShard(req.Context(), func(ctx context.Context, client *redis.Client) error {
+		return client.Ping(ctx).Err()
+	})
+	if err != nil {
+		WriteResponse(res, http.StatusInternalServerError, fmt.Errorf("failed to ping backfeed redis: %s", err))
+		return
+	}
+	WriteResponse(res, http.StatusOK, "ok")
+}
+
+func (that *GlobalBackfeedManager) HandlePing(res http.ResponseWriter, _ *http.Request) {
+	WriteResponse(res, http.StatusOK, "pong")
+}
+
 func (that *GlobalBackfeedManager) CancelAllFeeds() {
+	that.Populated.UnSet()
 	that.Cancel()
 	for project, projectBackfeedManager := range that.ActiveFeeds {
 		log.Printf("waiting for %s channel to shut down...", project)
@@ -513,7 +543,9 @@ func main() {
 		log.Panicf("unable to set up backfeed projects: %s", err)
 	}
 	r := mux.NewRouter()
-	r.Methods(http.MethodPost).Path("/legacy/{slug}").HandlerFunc(globalBackfeedManager.Handle)
+	r.Methods(http.MethodPost).Path("/legacy/{slug}").HandlerFunc(globalBackfeedManager.HandleLegacy)
+	r.Methods(http.MethodGet).Path("/ping").HandlerFunc(globalBackfeedManager.HandlePing)
+	r.Methods(http.MethodGet).Path("/health").HandlerFunc(globalBackfeedManager.HandleHealth)
 	rMetrics := mux.NewRouter()
 	rMetrics.PathPrefix("/debug/pprof/").Handler(http.DefaultServeMux)
 	rMetrics.Path("/metrics").Handler(promhttp.Handler())

vendor/github.com/tevino/abool/v2/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Tevin Zhang
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/tevino/abool/v2/bool.go

@@ -0,0 +1,87 @@
+// Package abool provides atomic Boolean type for cleaner code and
+// better performance.
+package abool
+
+import (
+	"encoding/json"
+	"sync/atomic"
+)
+
+// New creates an AtomicBool with default set to false.
+func New() *AtomicBool {
+	return new(AtomicBool)
+}
+
+// NewBool creates an AtomicBool with given default value.
+func NewBool(ok bool) *AtomicBool {
+	ab := New()
+	if ok {
+		ab.Set()
+	}
+	return ab
+}
+
+// AtomicBool is an atomic Boolean.
+// Its methods are all atomic, thus safe to be called by multiple goroutines simultaneously.
+// Note: When embedding into a struct one should always use *AtomicBool to avoid copy.
+type AtomicBool int32
+
+// Set sets the Boolean to true.
+func (ab *AtomicBool) Set() {
+	atomic.StoreInt32((*int32)(ab), 1)
+}
+
+// UnSet sets the Boolean to false.
+func (ab *AtomicBool) UnSet() {
+	atomic.StoreInt32((*int32)(ab), 0)
+}
+
+// IsSet returns whether the Boolean is true.
+func (ab *AtomicBool) IsSet() bool {
+	return atomic.LoadInt32((*int32)(ab)) == 1
+}
+
+// IsNotSet returns whether the Boolean is false.
+func (ab *AtomicBool) IsNotSet() bool {
+	return !ab.IsSet()
+}
+
+// SetTo sets the boolean with given Boolean.
+func (ab *AtomicBool) SetTo(yes bool) {
+	if yes {
+		atomic.StoreInt32((*int32)(ab), 1)
+	} else {
+		atomic.StoreInt32((*int32)(ab), 0)
+	}
+}
+
+// SetToIf sets the Boolean to new only if the Boolean matches the old.
+// Returns whether the set was done.
+func (ab *AtomicBool) SetToIf(old, new bool) (set bool) {
+	var o, n int32
+	if old {
+		o = 1
+	}
+	if new {
+		n = 1
+	}
+	return atomic.CompareAndSwapInt32((*int32)(ab), o, n)
+}
+
+// MarshalJSON behaves the same as if the AtomicBool is a builtin.bool.
+// NOTE: There's no lock during the process, usually it shouldn't be called with other methods in parallel.
+func (ab *AtomicBool) MarshalJSON() ([]byte, error) {
+	return json.Marshal(ab.IsSet())
+}
+
+// UnmarshalJSON behaves the same as if the AtomicBool is a builtin.bool.
+// NOTE: There's no lock during the process, usually it shouldn't be called with other methods in parallel.
+func (ab *AtomicBool) UnmarshalJSON(b []byte) error {
+	var v bool
+	err := json.Unmarshal(b, &v)
+
+	if err == nil {
+		ab.SetTo(v)
+	}
+	return err
+}

vendor/modules.txt

@@ -48,6 +48,9 @@ github.com/prometheus/common/model
 github.com/prometheus/procfs
 github.com/prometheus/procfs/internal/fs
 github.com/prometheus/procfs/internal/util
+# github.com/tevino/abool/v2 v2.0.1
+## explicit; go 1.17
+github.com/tevino/abool/v2
 # golang.org/x/sys v0.0.0-20220114195835-da31bd327af9
 ## explicit; go 1.17
 golang.org/x/sys/internal/unsafeheader