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()
// Log domain
logger := log.NewLogfmtLogger(os.Stderr)
logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC).With("caller", log.DefaultCaller)
stdlog.SetFlags(0) // flags are handled by Go kit's logger
stdlog.SetOutput(log.NewStdlibAdapter(logger)) // redirect anything using stdlib log to us
// Service discovery domain. In this example we use Consul.
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)
}
discoveryClient := consul.NewClient(consulClient)
// Context domain.
ctx := context.Background()
// Set up our routes.
//
// Each Consul service name maps to multiple instances of that service. We
// connect to each instance according to its pre-determined transport: in this
// case, we choose to access addsvc via its gRPC client, and stringsvc over
// plain transport/http (it has no client package).
//
// Each service instance implements multiple methods, and we want to map each
// method to a unique path on the API gateway. So, we define that path and its
// corresponding factory function, which takes an instance string and returns an
// endpoint.Endpoint for the specific method.
//
// Finally, we mount that path + endpoint handler into the router.
r := mux.NewRouter()
for consulName, methods := range map[string][]struct {
path string
factory loadbalancer.Factory
}{
"addsvc": {
{path: "/api/addsvc/concat", factory: grpc.MakeConcatEndpointFactory(opentracing.GlobalTracer(), nil)},
{path: "/api/addsvc/sum", factory: grpc.MakeSumEndpointFactory(opentracing.GlobalTracer(), nil)},
},
"stringsvc": {
{path: "/api/stringsvc/uppercase", factory: httpFactory(ctx, "GET", "uppercase/")},
{path: "/api/stringsvc/concat", factory: httpFactory(ctx, "GET", "concat/")},
},
} {
for _, method := range methods {
publisher, err := consul.NewPublisher(discoveryClient, method.factory, logger, consulName)
if err != nil {
logger.Log("service", consulName, "path", method.path, "err", err)
continue
}
lb := loadbalancer.NewRoundRobin(publisher)
e := loadbalancer.Retry(*retryMax, *retryTimeout, lb)
h := makeHandler(ctx, e, logger)
r.HandleFunc(method.path, h)
}
}
// Mechanical stuff.
errc := make(chan error)
go func() {
errc <- interrupt()
}()
go func() {
logger.Log("transport", "http", "addr", *httpAddr)
errc <- http.ListenAndServe(*httpAddr, r)
}()
logger.Log("err", <-errc)
}
func main() {
var (
transport = flag.String("transport", "httpjson", "httpjson, grpc, netrpc, thrift")
httpAddrs = flag.String("http.addrs", "localhost:8001", "Comma-separated list of addresses for HTTP (JSON) servers")
grpcAddrs = flag.String("grpc.addrs", "localhost:8002", "Comma-separated list of addresses for gRPC servers")
netrpcAddrs = flag.String("netrpc.addrs", "localhost:8003", "Comma-separated list of addresses for net/rpc servers")
thriftAddrs = flag.String("thrift.addrs", "localhost:8004", "Comma-separated list of addresses for Thrift servers")
thriftProtocol = flag.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
thriftBufferSize = flag.Int("thrift.buffer.size", 0, "0 for unbuffered")
thriftFramed = flag.Bool("thrift.framed", false, "true to enable framing")
// Two OpenTracing backends (to demonstrate how they can be interchanged):
appdashAddr = flag.String("appdash.addr", "", "Enable Appdash tracing via an Appdash server host:port")
lightstepAccessToken = flag.String("lightstep.token", "", "Enable LightStep tracing via a LightStep access token")
)
flag.Parse()
if len(os.Args) < 4 {
fmt.Fprintf(os.Stderr, "\n%s [flags] method arg1 arg2\n\n", filepath.Base(os.Args[0]))
flag.Usage()
os.Exit(1)
}
randomSeed := time.Now().UnixNano()
root := context.Background()
method, s1, s2 := flag.Arg(0), flag.Arg(1), flag.Arg(2)
var logger log.Logger
logger = log.NewLogfmtLogger(os.Stdout)
logger = log.NewContext(logger).With("caller", log.DefaultCaller)
logger = log.NewContext(logger).With("transport", *transport)
tracingLogger := log.NewContext(logger).With("component", "tracing")
// Set up OpenTracing
var tracer opentracing.Tracer
{
switch {
case *appdashAddr != "" && *lightstepAccessToken == "":
tracer = appdashot.NewTracer(appdash.NewRemoteCollector(*appdashAddr))
case *appdashAddr == "" && *lightstepAccessToken != "":
tracer = lightstep.NewTracer(lightstep.Options{
AccessToken: *lightstepAccessToken,
})
defer lightstep.FlushLightStepTracer(tracer)
case *appdashAddr == "" && *lightstepAccessToken == "":
tracer = opentracing.GlobalTracer() // no-op
default:
panic("specify either -appdash.addr or -lightstep.access.token, not both")
}
}
var (
instances []string
sumFactory, concatFactory loadbalancer.Factory
)
switch *transport {
case "grpc":
instances = strings.Split(*grpcAddrs, ",")
sumFactory = grpcclient.MakeSumEndpointFactory(tracer, tracingLogger)
concatFactory = grpcclient.MakeConcatEndpointFactory(tracer, tracingLogger)
case "httpjson":
instances = strings.Split(*httpAddrs, ",")
for i, rawurl := range instances {
if !strings.HasPrefix("http", rawurl) {
instances[i] = "http://" + rawurl
}
}
sumFactory = httpjsonclient.MakeSumEndpointFactory(tracer, tracingLogger)
concatFactory = httpjsonclient.MakeConcatEndpointFactory(tracer, tracingLogger)
case "netrpc":
instances = strings.Split(*netrpcAddrs, ",")
sumFactory = netrpcclient.SumEndpointFactory
concatFactory = netrpcclient.ConcatEndpointFactory
case "thrift":
instances = strings.Split(*thriftAddrs, ",")
thriftClient := thriftclient.New(*thriftProtocol, *thriftBufferSize, *thriftFramed, logger)
sumFactory = thriftClient.SumEndpoint
concatFactory = thriftClient.ConcatEndpoint
default:
logger.Log("err", "invalid transport")
os.Exit(1)
}
sum := buildEndpoint(tracer, "sum", instances, sumFactory, randomSeed, logger)
concat := buildEndpoint(tracer, "concat", instances, concatFactory, randomSeed, logger)
svc := newClient(root, sum, concat, logger)
begin := time.Now()
switch method {
case "sum":
a, _ := strconv.Atoi(s1)
b, _ := strconv.Atoi(s2)
v := svc.Sum(a, b)
logger.Log("method", "sum", "a", a, "b", b, "v", v, "took", time.Since(begin))
case "concat":
a, b := s1, s2
v := svc.Concat(a, b)
logger.Log("method", "concat", "a", a, "b", b, "v", v, "took", time.Since(begin))
default:
logger.Log("err", "invalid method "+method)
os.Exit(1)
}
}