Service skeleton with health check endpoints

Closes #1 (closed)

FYI: @tziai

cmd/cache/main.go

+package main
+
+import (
+	"context"
+	"errors"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/kelseyhightower/envconfig"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	goahttp "goa.design/goa/v3/http"
+	goa "goa.design/goa/v3/pkg"
+	"golang.org/x/sync/errgroup"
+
+	goahealth "code.vereign.com/gaiax/tsa/cache/gen/health"
+	goahealthsrv "code.vereign.com/gaiax/tsa/cache/gen/http/health/server"
+	goaopenapisrv "code.vereign.com/gaiax/tsa/cache/gen/http/openapi/server"
+	"code.vereign.com/gaiax/tsa/cache/gen/openapi"
+	"code.vereign.com/gaiax/tsa/cache/internal/config"
+	"code.vereign.com/gaiax/tsa/cache/internal/service"
+	"code.vereign.com/gaiax/tsa/cache/internal/service/health"
+	"code.vereign.com/gaiax/tsa/golib/graceful"
+)
+
+var Version = "0.0.0+development"
+
+func main() {
+	var cfg config.Config
+	if err := envconfig.Process("", &cfg); err != nil {
+		log.Fatalf("cannot load configuration: %v", err)
+	}
+
+	logger, err := createLogger(cfg.LogLevel)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	defer logger.Sync() //nolint:errcheck
+
+	logger.Info("start cache service", zap.String("version", Version), zap.String("goa", goa.Version()))
+
+	// create services
+	var (
+		healthSvc goahealth.Service
+	)
+	{
+		healthSvc = health.New()
+	}
+
+	// create endpoints
+	var (
+		healthEndpoints  *goahealth.Endpoints
+		openapiEndpoints *openapi.Endpoints
+	)
+	{
+		healthEndpoints = goahealth.NewEndpoints(healthSvc)
+		openapiEndpoints = openapi.NewEndpoints(nil)
+	}
+
+	// Provide the transport specific request decoder and response encoder.
+	// The goa http package has built-in support for JSON, XML and gob.
+	// Other encodings can be used by providing the corresponding functions,
+	// see goa.design/implement/encoding.
+	var (
+		dec = goahttp.RequestDecoder
+		enc = goahttp.ResponseEncoder
+	)
+
+	// Build the service HTTP request multiplexer and configure it to serve
+	// HTTP requests to the service endpoints.
+	mux := goahttp.NewMuxer()
+
+	var (
+		healthServer  *goahealthsrv.Server
+		openapiServer *goaopenapisrv.Server
+	)
+	{
+		healthServer = goahealthsrv.New(healthEndpoints, mux, dec, enc, nil, errFormatter)
+		openapiServer = goaopenapisrv.New(openapiEndpoints, mux, dec, enc, nil, errFormatter, nil, nil)
+	}
+
+	// Configure the mux.
+	goahealthsrv.Mount(mux, healthServer)
+	goaopenapisrv.Mount(mux, openapiServer)
+
+	var handler http.Handler = mux
+	srv := &http.Server{
+		Addr:         cfg.HTTP.Host + ":" + cfg.HTTP.Port,
+		Handler:      handler,
+		IdleTimeout:  cfg.HTTP.IdleTimeout,
+		ReadTimeout:  cfg.HTTP.ReadTimeout,
+		WriteTimeout: cfg.HTTP.WriteTimeout,
+	}
+
+	g, ctx := errgroup.WithContext(context.Background())
+	g.Go(func() error {
+		if err := graceful.Shutdown(ctx, srv, 20*time.Second); err != nil {
+			logger.Error("server shutdown error", zap.Error(err))
+			return err
+		}
+		return errors.New("server stopped successfully")
+	})
+	if err := g.Wait(); err != nil {
+		logger.Error("run group stopped", zap.Error(err))
+	}
+
+	logger.Info("bye bye")
+}
+
+func createLogger(logLevel string, opts ...zap.Option) (*zap.Logger, error) {
+	var level = zapcore.InfoLevel
+	if logLevel != "" {
+		err := level.UnmarshalText([]byte(logLevel))
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	config := zap.NewProductionConfig()
+	config.Level = zap.NewAtomicLevelAt(level)
+	config.DisableStacktrace = true
+	config.EncoderConfig.TimeKey = "ts"
+	config.EncoderConfig.EncodeTime = zapcore.RFC3339TimeEncoder
+	return config.Build(opts...)
+}
+
+func errFormatter(e error) goahttp.Statuser {
+	return service.NewErrorResponse(e)
+}