Beispiel #1
0
// New returns a service that's load-balanced over instances of restsvc found
// in the provided Consul server. The mechanism of looking up restsvc
// instances in Consul is hard-coded into the client.
func New(consulAddr string, logger log.Logger) (restsvc.Service, error) {
	apiclient, err := consulapi.NewClient(&consulapi.Config{
		Address: consulAddr,
	})
	if err != nil {
		return nil, err
	}

	// As the implementer of restsvc, we declare and enforce these
	// parameters for all of the restsvc consumers.
	var (
		consulService = "restsvc"
		consulTags    = []string{"prod"}
		passingOnly   = true
		retryMax      = 3
		retryTimeout  = 500 * time.Millisecond
	)

	var (
		sdclient  = consul.NewClient(apiclient)
		endpoints restsvc.Endpoints
	)
	{
		factory := factoryFor(restsvc.MakePostConfigEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.PostConfigEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakeGetConfigEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.GetConfigEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakePutConfigEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.PutConfigEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakePatchConfigEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.PatchConfigEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakeDeleteConfigEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.DeleteConfigEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakeGetAddressesEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.GetAddressesEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakeGetAddressEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.GetAddressEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakePostAddressEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.PostAddressEndpoint = retry
	}
	{
		factory := factoryFor(restsvc.MakeDeleteAddressEndpoint)
		subscriber := consul.NewSubscriber(sdclient, factory, logger, consulService, consulTags, passingOnly)
		balancer := lb.NewRoundRobin(subscriber)
		retry := lb.Retry(retryMax, retryTimeout, balancer)
		endpoints.DeleteAddressEndpoint = retry
	}

	return endpoints, nil
}
Beispiel #2
0
func main() {
	var (
		httpAddr     = flag.String("http.addr", ":8000", "Address for HTTP (JSON) server")
		consulAddr   = flag.String("consul.addr", "", "Consul agent address")
		retryMax     = flag.Int("retry.max", 3, "per-request retries to different instances")
		retryTimeout = flag.Duration("retry.timeout", 500*time.Millisecond, "per-request timeout, including retries")
	)
	flag.Parse()

	// Logging domain.
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stderr)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC)
		logger = log.NewContext(logger).With("caller", log.DefaultCaller)
	}

	// Service discovery domain. In this example we use Consul.
	var client consulsd.Client
	{
		consulConfig := api.DefaultConfig()
		if len(*consulAddr) > 0 {
			consulConfig.Address = *consulAddr
		}
		consulClient, err := api.NewClient(consulConfig)
		if err != nil {
			logger.Log("err", err)
			os.Exit(1)
		}
		client = consulsd.NewClient(consulClient)
	}

	// Transport domain.
	tracer := stdopentracing.GlobalTracer() // no-op
	ctx := context.Background()
	r := mux.NewRouter()

	// Now we begin installing the routes. Each route corresponds to a single
	// method: sum, concat, uppercase, and count.

	// addsvc routes.
	{
		// Each method gets constructed with a factory. Factories take an
		// instance string, and return a specific endpoint. In the factory we
		// dial the instance string we get from Consul, and then leverage an
		// addsvc client package to construct a complete service. We can then
		// leverage the addsvc.Make{Sum,Concat}Endpoint constructors to convert
		// the complete service to specific endpoint.

		var (
			tags        = []string{}
			passingOnly = true
			endpoints   = addsvc.Endpoints{}
		)
		{
			factory := addsvcFactory(addsvc.MakeSumEndpoint, tracer, logger)
			subscriber := consulsd.NewSubscriber(client, factory, logger, "addsvc", tags, passingOnly)
			balancer := lb.NewRoundRobin(subscriber)
			retry := lb.Retry(*retryMax, *retryTimeout, balancer)
			endpoints.SumEndpoint = retry
		}
		{
			factory := addsvcFactory(addsvc.MakeConcatEndpoint, tracer, logger)
			subscriber := consulsd.NewSubscriber(client, factory, logger, "addsvc", tags, passingOnly)
			balancer := lb.NewRoundRobin(subscriber)
			retry := lb.Retry(*retryMax, *retryTimeout, balancer)
			endpoints.ConcatEndpoint = retry
		}

		// Here we leverage the fact that addsvc comes with a constructor for an
		// HTTP handler, and just install it under a particular path prefix in
		// our router.

		r.PathPrefix("addsvc/").Handler(addsvc.MakeHTTPHandler(ctx, endpoints, tracer, logger))
	}

	// stringsvc routes.
	{
		// addsvc had lots of nice importable Go packages we could leverage.
		// With stringsvc we are not so fortunate, it just has some endpoints
		// that we assume will exist. So we have to write that logic here. This
		// is by design, so you can see two totally different methods of
		// proxying to a remote service.

		var (
			tags        = []string{}
			passingOnly = true
			uppercase   endpoint.Endpoint
			count       endpoint.Endpoint
		)
		{
			factory := stringsvcFactory(ctx, "GET", "/uppercase")
			subscriber := consulsd.NewSubscriber(client, factory, logger, "stringsvc", tags, passingOnly)
			balancer := lb.NewRoundRobin(subscriber)
			retry := lb.Retry(*retryMax, *retryTimeout, balancer)
			uppercase = retry
		}
		{
			factory := stringsvcFactory(ctx, "GET", "/count")
			subscriber := consulsd.NewSubscriber(client, factory, logger, "stringsvc", tags, passingOnly)
			balancer := lb.NewRoundRobin(subscriber)
			retry := lb.Retry(*retryMax, *retryTimeout, balancer)
			count = retry
		}

		// We can use the transport/http.Server to act as our handler, all we
		// have to do provide it with the encode and decode functions for our
		// stringsvc methods.

		r.Handle("/stringsvc/uppercase", httptransport.NewServer(ctx, uppercase, decodeUppercaseRequest, encodeJSONResponse))
		r.Handle("/stringsvc/count", httptransport.NewServer(ctx, count, decodeCountRequest, encodeJSONResponse))
	}

	// Interrupt handler.
	errc := make(chan error)
	go func() {
		c := make(chan os.Signal)
		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
		errc <- fmt.Errorf("%s", <-c)
	}()

	// HTTP transport.
	go func() {
		logger.Log("transport", "HTTP", "addr", *httpAddr)
		errc <- http.ListenAndServe(*httpAddr, r)
	}()

	// Run!
	logger.Log("exit", <-errc)
}