feat: add /health-check

Dockerfile

@@ -4,6 +4,9 @@ LABEL org.opencontainers.image.source="https://github.com/powerman/go-monolith-e
 
 WORKDIR /app
 
+HEALTHCHECK --interval=30s --timeout=5s \
+    CMD wget -q -O - http://$HOSTNAME:17000/health-check || exit 1
+
 COPY . .
 
 ENTRYPOINT [ "bin/mono" ]

README.md

@@ -187,7 +187,6 @@ $ ./bin/mono serve
 ## TODO
 
 - [ ] Update srv/jsonrpc2 to use HTTP mux and CORS middleware.
-- [ ] Add /health-check.
 - [ ] Add gRPC service example.
 - [ ] Add OpenAPI service example.
 - [ ] Add NATS/STAN publish/subscribe example.

cmd/mono/main.go

@@ -16,7 +16,7 @@ import (
 
 	"github.com/powerman/go-monolith-example/internal/config"
 	"github.com/powerman/go-monolith-example/ms/example"
-	"github.com/powerman/go-monolith-example/ms/metrics"
+	"github.com/powerman/go-monolith-example/ms/mono"
 	"github.com/powerman/go-monolith-example/pkg/cobrax"
 	"github.com/powerman/go-monolith-example/pkg/concurrent"
 	"github.com/powerman/go-monolith-example/pkg/def"
@@ -34,7 +34,7 @@ type embeddedService interface {
 //nolint:gochecknoglobals // Main.
 var (
 	embeddedServices = []embeddedService{
-		&metrics.Service{},
+		&mono.Service{},
 		&example.Service{},
 	}
 

env.sh.dist

@@ -22,8 +22,8 @@ export mono_nats_addr_port="4222"
 #   <OTHER>                 - used by 3rd-party libraries/frameworks/tools
 export GO_TEST_TIME_FACTOR="1.0" # Increase if tests fail because of slow CPU.
 export MONO_EXAMPLE_ADDR_PORT="17001"
-export MONO_EXAMPLE_METRICS_ADDR_PORT="16001"
-export MONO_METRICS_ADDR_PORT="16000"
+export MONO_EXAMPLE_METRICS_ADDR_PORT="17002"
+export MONO_MONO_ADDR_PORT="17000"
 export MONO_X_MYSQL_ADDR_HOST="localhost"
 export MONO_X_MYSQL_ADDR_PORT="${mono_mysql_addr_port}"
 export MONO_X_NATS_ADDR_URLS="nats://localhost:${mono_nats_addr_port}"

internal/config/config.go

@@ -20,33 +20,28 @@ const EnvPrefix = "MONO_"
 
 // Shared contains configurable values shared by microservices.
 type Shared struct {
+	AddrHost               appcfg.NotEmptyString `env:"ADDR_HOST"`
+	AddrHostInt            appcfg.NotEmptyString `env:"ADDR_HOST_INT"`
 	ExampleAddrPort        appcfg.Port           `env:"EXAMPLE_ADDR_PORT"`
 	ExampleMetricsAddrPort appcfg.Port           `env:"EXAMPLE_METRICS_ADDR_PORT"`
-	MonoAddrHost           appcfg.NotEmptyString `env:"MONO_ADDR_HOST"`
-	MonoMetricsAddrHost    appcfg.NotEmptyString `env:"MONO_METRICS_ADDR_HOST"`
 	XMySQLAddrHost         appcfg.NotEmptyString `env:"X_MYSQL_ADDR_HOST"`
 	XMySQLAddrPort         appcfg.Port           `env:"X_MYSQL_ADDR_PORT"`
 	XNATSAddrUrls          appcfg.NotEmptyString `env:"X_NATS_ADDR_URLS"`
 	XSTANClusterID         appcfg.NotEmptyString `env:"X_STAN_CLUSTER_ID"`
 }
 
-// Default ports for metrics.
-const (
-	MetricsPort = 16000 + iota // XXX Used in ms/metrics/service.go.
-	ExampleMetricsPort
-)
-
 // Default ports.
 const (
-	_ = 17000 + iota
+	MonoPort = 17000 + iota
 	ExamplePort
+	ExampleMetricsPort
 )
 
 var shared = &Shared{ //nolint:gochecknoglobals // Config is global anyway.
+	AddrHost:               appcfg.MustNotEmptyString(def.Hostname),
+	AddrHostInt:            appcfg.MustNotEmptyString(def.Hostname),
 	ExampleAddrPort:        appcfg.MustPort(strconv.Itoa(ExamplePort)),
 	ExampleMetricsAddrPort: appcfg.MustPort(strconv.Itoa(ExampleMetricsPort)),
-	MonoAddrHost:           appcfg.MustNotEmptyString(def.Hostname),
-	MonoMetricsAddrHost:    appcfg.MustNotEmptyString(def.Hostname),
 	XMySQLAddrPort:         appcfg.MustPort("3306"),
 }
 

ms/example/internal/config/config.go

@@ -81,10 +81,10 @@ func Init(sharedCfg *SharedCfg, flagsets FlagSets) error {
 	appcfg.AddPFlag(fs.Serve, &own.MySQLName, pfx+"mysql.dbname", "MySQL database name")
 	appcfg.AddPFlag(fs.Serve, &shared.XNATSAddrUrls, "nats.urls", "URLs to connect to NATS (separated by comma)")
 	appcfg.AddPFlag(fs.Serve, &shared.XSTANClusterID, "stan.cluster_id", "STAN cluster ID")
-	appcfg.AddPFlag(fs.Serve, &shared.MonoMetricsAddrHost, "metrics.host", "host to serve Prometheus metrics")
-	appcfg.AddPFlag(fs.Serve, &shared.ExampleMetricsAddrPort, pfx+"metrics.port", "port to serve Prometheus metrics")
-	appcfg.AddPFlag(fs.Serve, &shared.MonoAddrHost, "host", "host to serve")
+	appcfg.AddPFlag(fs.Serve, &shared.AddrHost, "host", "host to serve")
+	appcfg.AddPFlag(fs.Serve, &shared.AddrHostInt, "host-int", "internal host to serve")
 	appcfg.AddPFlag(fs.Serve, &shared.ExampleAddrPort, pfx+"port", "port to serve")
+	appcfg.AddPFlag(fs.Serve, &shared.ExampleMetricsAddrPort, pfx+"metrics.port", "port to serve Prometheus metrics")
 
 	return nil
 }
@@ -113,8 +113,8 @@ func GetServe() (c *ServeConfig, err error) {
 		MySQLGooseDir: own.GooseDir.Value(&err),
 		NATSURLs:      shared.XNATSAddrUrls.Value(&err),
 		STANClusterID: shared.XSTANClusterID.Value(&err),
-		Addr:          netx.NewAddr(shared.MonoAddrHost.Value(&err), shared.ExampleAddrPort.Value(&err)),
-		MetricsAddr:   netx.NewAddr(shared.MonoMetricsAddrHost.Value(&err), shared.ExampleMetricsAddrPort.Value(&err)),
+		Addr:          netx.NewAddr(shared.AddrHost.Value(&err), shared.ExampleAddrPort.Value(&err)),
+		MetricsAddr:   netx.NewAddr(shared.AddrHostInt.Value(&err), shared.ExampleMetricsAddrPort.Value(&err)),
 	}
 	if err != nil {
 		return nil, appcfg.WrapPErr(err, fs.Serve, own, shared)

ms/example/internal/config/config_test.go

@@ -68,8 +68,8 @@ func Test(t *testing.T) {
 			"--nats.urls=nats://nats4:4222",
 			"--stan.cluster_id=cluster4",
 			"--host=host4",
+			"--host-int=metrics4",
 			"--example.port=8004",
-			"--metrics.host=metrics4",
 			"--example.metrics.port=4",
 		)
 		t.Nil(err)

ms/mono/health-check.go

@@ -0,0 +1,7 @@
+package mono
+
+import "net/http"
+
+func (s *Service) serveHealthCheck(w http.ResponseWriter, r *http.Request) {
+	_, _ = w.Write([]byte("OK"))
+}

ms/metrics/metrics.go → ms/mono/metrics.go

@@ -1,4 +1,4 @@
-package metrics
+package mono
 
 import (
 	"runtime"

ms/metrics/service.go → ms/mono/service.go

@@ -1,8 +1,9 @@
-// Package metrics provides embedded microservice.
-package metrics
+// Package mono provides embedded microservice.
+package mono
 
 import (
 	"context"
+	"net/http"
 	"regexp"
 	"strconv"
 
@@ -27,9 +28,9 @@ var (
 	fs     *pflag.FlagSet
 	shared *config.Shared
 	own    = &struct {
-		MetricsPort appcfg.Port `env:"METRICS_ADDR_PORT"`
+		Port appcfg.Port `env:"MONO_ADDR_PORT"`
 	}{
-		MetricsPort: appcfg.MustPort(strconv.Itoa(config.MetricsPort)),
+		Port: appcfg.MustPort(strconv.Itoa(config.MonoPort)),
 	}
 
 	reg = prometheus.NewPedanticRegistry()
@@ -38,12 +39,13 @@ var (
 // Service implements main.embeddedService interface.
 type Service struct {
 	cfg struct {
-		metricsAddr netx.Addr
+		addr netx.Addr
 	}
+	mux *http.ServeMux
 }
 
 // Name implements main.embeddedService interface.
-func (s *Service) Name() string { return "metrics" }
+func (s *Service) Name() string { return "mono" }
 
 // Init implements main.embeddedService interface.
 func (s *Service) Init(sharedCfg *config.Shared, _, serveCmd *cobra.Command) error {
@@ -53,28 +55,33 @@ func (s *Service) Init(sharedCfg *config.Shared, _, serveCmd *cobra.Command) err
 	fs, shared = serveCmd.Flags(), sharedCfg
 	fromEnv := appcfg.NewFromEnv(config.EnvPrefix)
 	err := appcfg.ProvideStruct(own, fromEnv)
-	appcfg.AddPFlag(fs, &shared.MonoMetricsAddrHost, "metrics.host", "host to serve Prometheus metrics")
-	appcfg.AddPFlag(fs, &own.MetricsPort, "metrics.port", "port to serve Prometheus metrics")
+	pfx := s.Name() + "."
+	appcfg.AddPFlag(fs, &shared.AddrHostInt, "host-int", "internal host to serve")
+	appcfg.AddPFlag(fs, &own.Port, pfx+"port", "port to serve monolith introspection")
 	return err
 }
 
 // RunServe implements main.embeddedService interface.
 func (s *Service) RunServe(_, ctxShutdown Ctx, shutdown func()) (err error) {
 	log := structlog.FromContext(ctxShutdown, nil)
-	s.cfg.metricsAddr = netx.NewAddr(shared.MonoMetricsAddrHost.Value(&err), own.MetricsPort.Value(&err))
+	s.cfg.addr = netx.NewAddr(shared.AddrHostInt.Value(&err), own.Port.Value(&err))
 	if err != nil {
 		return log.Err("failed to get config", "err", appcfg.WrapPErr(err, fs, shared, own))
 	}
 
+	s.mux = http.NewServeMux()
+	serve.HandleMetrics(s.mux, reg)
+	s.mux.Handle("/health-check", http.HandlerFunc(s.serveHealthCheck))
+
 	err = concurrent.Serve(ctxShutdown, shutdown,
-		s.serveMetrics,
+		s.serveHTTP,
 	)
 	if err != nil {
 		return log.Err("failed to serve", "err", err)
 	}
 	return nil
 }
 
-func (s *Service) serveMetrics(ctx Ctx) error {
-	return serve.Metrics(ctx, s.cfg.metricsAddr, reg)
+func (s *Service) serveHTTP(ctx Ctx) error {
+	return serve.HTTP(ctx, s.cfg.addr, s.mux, "monolith introspection")
 }

pkg/serve/serve.go

@@ -48,12 +48,17 @@ func HTTP(ctx Ctx, addr netx.Addr, handler http.Handler, service string) error {
 // Metrics starts HTTP server on addr path /metrics using reg as
 // prometheus handler.
 func Metrics(ctx Ctx, addr netx.Addr, reg *prometheus.Registry) error {
-	handler := promhttp.InstrumentMetricHandler(reg, promhttp.HandlerFor(reg, promhttp.HandlerOpts{}))
 	mux := http.NewServeMux()
-	mux.Handle("/metrics", handler)
+	HandleMetrics(mux, reg)
 	return HTTP(ctx, addr, mux, "Prometheus metrics")
 }
 
+// HandleMetrics adds reg's prometheus handler on /metrics at mux.
+func HandleMetrics(mux *http.ServeMux, reg *prometheus.Registry) {
+	handler := promhttp.InstrumentMetricHandler(reg, promhttp.HandlerFor(reg, promhttp.HandlerOpts{}))
+	mux.Handle("/metrics", handler)
+}
+
 // RPC starts HTTP server on addr path /rpc using rcvr as JSON-RPC 2.0
 // handler.
 func RPC(ctx Ctx, addr netx.Addr, rcvr interface{}) error {