Add basic health checks

Signed-off-by: Nikolai Rodionov <iam@allanger.xyz>

cmd/server.go

@@ -2,6 +2,7 @@ package cmd
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 	"net"
 	"strings"
@@ -21,6 +22,9 @@ import (
 	_ "github.com/jackc/pgx/v5/stdlib"
 	"github.com/redis/go-redis/v9"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/health"
+	healthgrpc "google.golang.org/grpc/health/grpc_health_v1"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
 	"google.golang.org/grpc/reflection"
 )
 
@@ -44,6 +48,8 @@ type Server struct {
 	// Dev and logging
 	Reflection bool `env:"SOFTPLAYER_REFLECTION" default:"false"`
 	DevMode    bool `env:"SOFTPLAYER_DEV_MODE" default:"false"`
+	// HealthChecks
+	HealthCheckInterval time.Duration `env:"SOFTPLAYER_HEALTH_CHECK_INTERVAL" default:"5s"`
 }
 
 // Run the grpc backend server
@@ -121,6 +127,33 @@ func (cmd *Server) Run(ctx context.Context) error {
 	tokens.RegisterTokensServiceServer(grpcServer, v1.NewTokensServer(tokenCtrl, authController))
 	tokens.RegisterPublicTokensServiceServer(grpcServer, v1.NewPublicTokensServer(tokenCtrl, authController))
 
+	healthcheck := health.NewServer()
+	healthgrpc.RegisterHealthServer(grpcServer, healthcheck)
+
+	go func() {
+		ticker := time.NewTicker(10 * time.Second)
+		defer ticker.Stop()
+
+		for range ticker.C {
+
+			// Example checks
+			dbOK := checkDatabase(db)
+			redisOK := checkRedis(rdb)
+
+			status := healthpb.HealthCheckResponse_SERVING
+
+			if !dbOK || !redisOK {
+				status = healthpb.HealthCheckResponse_NOT_SERVING
+			}
+
+			healthcheck.SetServingStatus(
+				"",
+				status,
+			)
+
+		}
+	}()
+
 	info := grpcServer.GetServiceInfo()
 	tokenCtrl.SetGRPCInfo(info)
 	tokenCtrl.SetRules()
@@ -149,6 +182,10 @@ func selectorRequireAuth(ctx context.Context, callMeta interceptors.CallMeta) bo
 		return false
 	}
 
+	if serviceName == "Health" {
+		return false
+	}
+
 	if strings.Contains(serviceName, "ServerReflection") {
 		return false
 	}
@@ -159,3 +196,33 @@ func selectorRequireAuth(ctx context.Context, callMeta interceptors.CallMeta) bo
 
 	return true
 }
+
+func checkDatabase(db *sql.DB) bool {
+	ctx, cancel := context.WithTimeout(
+		context.Background(),
+		2*time.Second,
+	)
+	defer cancel()
+
+	// Fast connectivity check
+	if err := db.PingContext(ctx); err != nil {
+		return false
+	}
+
+	return true
+}
+
+func checkRedis(rdb *redis.Client) bool {
+	ctx, cancel := context.WithTimeout(
+		context.Background(),
+		2*time.Second,
+	)
+	defer cancel()
+
+	err := rdb.Ping(ctx).Err()
+	if err != nil {
+		return false
+	}
+
+	return true
+}