feat/add-readyz-endpoint

Author: ffelipelimao

cmd/commom/commom.go

@@ -62,7 +62,8 @@ func ServiceSetup(ctx context.Context, cancelFn context.CancelFunc, logConfig, c
 
 	launchTerminatingListenerGoroutine(cancelFn)
 
-	shutdownInternalServerFn := service.RunInternalServer(ctx, viperConfig)
+	healthDeps := service.InitHealthDependencies(viperConfig)
+	shutdownInternalServerFn := service.RunInternalServer(ctx, viperConfig, healthDeps)
 
 	return nil, viperConfig, shutdownInternalServerFn
 }

internal/service/health.go

@@ -0,0 +1,86 @@
+// MIT License
+//
+// Copyright (c) 2021 TFG Co
+//
+// 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.
+
+package service
+
+import (
+	"context"
+	"time"
+
+	"github.com/go-pg/pg/v10"
+	"github.com/go-redis/redis/v8"
+	"github.com/topfreegames/maestro/internal/config"
+)
+
+type HealthDependencies struct {
+	PostgresDB  *pg.DB
+	RedisClient *redis.Client
+}
+
+func InitHealthDependencies(c config.Config) *HealthDependencies {
+	deps := &HealthDependencies{}
+
+	if pgDB, err := initPostgresForHealth(c); err == nil {
+		deps.PostgresDB = pgDB
+	}
+
+	if redisClient, err := initRedisForHealth(c); err == nil {
+		deps.RedisClient = redisClient
+	}
+
+	return deps
+}
+
+func initPostgresForHealth(c config.Config) (*pg.DB, error) {
+	opts, err := connectToPostgres(c, GetSchedulerStoragePostgresURL(c))
+	if err != nil {
+		return nil, err
+	}
+	return pg.Connect(opts), nil
+}
+
+func initRedisForHealth(c config.Config) (*redis.Client, error) {
+	redisURL := c.GetString(schedulerCacheRedisURLPath)
+	if redisURL == "" {
+		redisURL = c.GetString(roomStorageRedisURLPath)
+	}
+	if redisURL == "" {
+		redisURL = c.GetString(operationStorageRedisURLPath)
+	}
+
+	return createRedisClient(c, redisURL, func(opts *redis.Options) {
+		opts.MaxRetries = 3
+	})
+}
+
+func checkPostgres(ctx context.Context, db *pg.DB) error {
+	ctx, cancel := context.WithTimeout(ctx, 2*time.Second)
+	defer cancel()
+	_, err := db.ExecContext(ctx, "SELECT 1")
+	return err
+}
+
+func checkRedis(ctx context.Context, client *redis.Client) error {
+	ctx, cancel := context.WithTimeout(ctx, 2*time.Second)
+	defer cancel()
+	return client.Ping(ctx).Err()
+}

internal/service/internal_api.go

@@ -36,12 +36,13 @@ import (
 // shutdown function. The internal server contains handlers for:
 // - health check
 // - metrics
-func RunInternalServer(ctx context.Context, configs config.Config) func() error {
+func RunInternalServer(ctx context.Context, configs config.Config, healthDeps *HealthDependencies) func() error {
 	mux := http.NewServeMux()
 	if configs.GetBool("internalApi.healthcheck.enabled") {
 		zap.L().Info("adding healthcheck handler to internal API")
 		mux.HandleFunc("/health", handleHealth)
 		mux.HandleFunc("/healthz", handleHealth)
+		mux.HandleFunc("/readyz", handleReadyz(healthDeps))
 	}
 	if configs.GetBool("internalApi.metrics.enabled") {
 		zap.L().Info("adding metrics handler to internal API")
@@ -69,6 +70,32 @@ func RunInternalServer(ctx context.Context, configs config.Config) func() error
 	}
 }
 
+func handleReadyz(deps *HealthDependencies) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		healthy := true
+
+		if deps.PostgresDB != nil {
+			if err := checkPostgres(r.Context(), deps.PostgresDB); err != nil {
+				healthy = false
+			}
+		}
+
+		if deps.RedisClient != nil {
+			if err := checkRedis(r.Context(), deps.RedisClient); err != nil {
+				healthy = false
+			}
+		}
+
+		if !healthy {
+			w.WriteHeader(http.StatusServiceUnavailable)
+		}
+
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("OK"))
+	}
+}
+
 func handleHealth(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	w.WriteHeader(http.StatusOK)