// New returns an AddService backed by an HTTP server living at the remote
// instance. We expect instance to come from a service discovery system, so
// likely of the form "host:port".
func New(instance string, tracer stdopentracing.Tracer, logger log.Logger) (addsvc.Service, error) {
if !strings.HasPrefix(instance, "http") {
instance = "http://" + instance
}
u, err := url.Parse(instance)
if err != nil {
return nil, err
}
// We construct a single ratelimiter middleware, to limit the total outgoing
// QPS from this client to all methods on the remote instance. We also
// construct per-endpoint circuitbreaker middlewares to demonstrate how
// that's done, although they could easily be combined into a single breaker
// for the entire remote instance, too.
limiter := ratelimit.NewTokenBucketLimiter(jujuratelimit.NewBucketWithRate(100, 100))
var sumEndpoint endpoint.Endpoint
{
sumEndpoint = httptransport.NewClient(
"POST",
copyURL(u, "/sum"),
addsvc.EncodeHTTPGenericRequest,
addsvc.DecodeHTTPSumResponse,
httptransport.ClientBefore(opentracing.ToHTTPRequest(tracer, logger)),
).Endpoint()
sumEndpoint = opentracing.TraceClient(tracer, "Sum")(sumEndpoint)
sumEndpoint = limiter(sumEndpoint)
sumEndpoint = circuitbreaker.Gobreaker(gobreaker.NewCircuitBreaker(gobreaker.Settings{
Name: "Sum",
Timeout: 30 * time.Second,
}))(sumEndpoint)
}
var concatEndpoint endpoint.Endpoint
{
concatEndpoint = httptransport.NewClient(
"POST",
copyURL(u, "/concat"),
addsvc.EncodeHTTPGenericRequest,
addsvc.DecodeHTTPConcatResponse,
httptransport.ClientBefore(opentracing.ToHTTPRequest(tracer, logger)),
).Endpoint()
concatEndpoint = opentracing.TraceClient(tracer, "Concat")(concatEndpoint)
concatEndpoint = limiter(concatEndpoint)
sumEndpoint = circuitbreaker.Gobreaker(gobreaker.NewCircuitBreaker(gobreaker.Settings{
Name: "Concat",
Timeout: 30 * time.Second,
}))(sumEndpoint)
}
return addsvc.Endpoints{
SumEndpoint: sumEndpoint,
ConcatEndpoint: concatEndpoint,
}, nil
}
func main() {
// Flag domain. Note that gRPC transitively registers flags via its import
// of glog. So, we define a new flag set, to keep those domains distinct.
fs := flag.NewFlagSet("", flag.ExitOnError)
var (
debugAddr = fs.String("debug.addr", ":8000", "Address for HTTP debug/instrumentation server")
httpAddr = fs.String("http.addr", ":8001", "Address for HTTP (JSON) server")
grpcAddr = fs.String("grpc.addr", ":8002", "Address for gRPC server")
thriftAddr = fs.String("thrift.addr", ":8003", "Address for Thrift server")
thriftProtocol = fs.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
thriftBufferSize = fs.Int("thrift.buffer.size", 0, "0 for unbuffered")
thriftFramed = fs.Bool("thrift.framed", false, "true to enable framing")
proxyHTTPAddr = fs.String("proxy.http.url", "", "if set, proxy requests over HTTP to this addsvc")
zipkinServiceName = fs.String("zipkin.service.name", "addsvc", "Zipkin service name")
zipkinCollectorAddr = fs.String("zipkin.collector.addr", "", "Zipkin Scribe collector address (empty will log spans)")
zipkinCollectorTimeout = fs.Duration("zipkin.collector.timeout", time.Second, "Zipkin collector timeout")
zipkinCollectorBatchSize = fs.Int("zipkin.collector.batch.size", 100, "Zipkin collector batch size")
zipkinCollectorBatchInterval = fs.Duration("zipkin.collector.batch.interval", time.Second, "Zipkin collector batch interval")
)
flag.Usage = fs.Usage // only show our flags
fs.Parse(os.Args[1:])
// `package log` domain
var logger kitlog.Logger
logger = kitlog.NewLogfmtLogger(os.Stderr)
logger = kitlog.With(logger, "ts", kitlog.DefaultTimestampUTC, "caller", kitlog.DefaultCaller)
stdlog.SetOutput(kitlog.NewStdlibAdapter(logger)) // redirect stdlib logging to us
stdlog.SetFlags(0) // flags are handled in our logger
// `package metrics` domain
requests := metrics.NewMultiCounter(
expvar.NewCounter("requests"),
statsd.NewCounter(ioutil.Discard, "requests_total", time.Second),
prometheus.NewCounter(stdprometheus.CounterOpts{
Namespace: "addsvc",
Subsystem: "add",
Name: "requests_total",
Help: "Total number of received requests.",
}, []string{}),
)
duration := metrics.NewMultiHistogram(
expvar.NewHistogram("duration_nanoseconds_total", 0, 100000000, 3),
statsd.NewHistogram(ioutil.Discard, "duration_nanoseconds_total", time.Second),
prometheus.NewSummary(stdprometheus.SummaryOpts{
Namespace: "addsvc",
Subsystem: "add",
Name: "duration_nanoseconds_total",
Help: "Total nanoseconds spend serving requests.",
}, []string{}),
)
// `package tracing` domain
zipkinHostPort := "localhost:1234" // TODO Zipkin makes overly simple assumptions about services
var zipkinCollector zipkin.Collector = loggingCollector{logger}
if *zipkinCollectorAddr != "" {
var err error
if zipkinCollector, err = zipkin.NewScribeCollector(
*zipkinCollectorAddr,
*zipkinCollectorTimeout,
*zipkinCollectorBatchSize,
*zipkinCollectorBatchInterval,
); err != nil {
logger.Log("err", err)
os.Exit(1)
}
}
zipkinMethodName := "add"
zipkinSpanFunc := zipkin.MakeNewSpanFunc(zipkinHostPort, *zipkinServiceName, zipkinMethodName)
zipkin.Log.Swap(logger) // log diagnostic/error details
// Our business and operational domain
var a Add = pureAdd
if *proxyHTTPAddr != "" {
codec := jsoncodec.New()
makeResponse := func() interface{} { return &addResponse{} }
var e endpoint.Endpoint
e = httptransport.NewClient(*proxyHTTPAddr, codec, makeResponse, httptransport.ClientBefore(zipkin.ToRequest(zipkinSpanFunc)))
e = zipkin.AnnotateClient(zipkinSpanFunc, zipkinCollector)(e)
a = proxyAdd(e, logger)
}
a = logging(logger)(a)
// Server domain
var e endpoint.Endpoint
e = makeEndpoint(a)
e = zipkin.AnnotateServer(zipkinSpanFunc, zipkinCollector)(e)
// Mechanical stuff
rand.Seed(time.Now().UnixNano())
root := context.Background()
errc := make(chan error)
go func() {
errc <- interrupt()
}()
// Transport: HTTP (debug/instrumentation)
go func() {
logger.Log("addr", *debugAddr, "transport", "debug")
errc <- http.ListenAndServe(*debugAddr, nil)
}()
// Transport: HTTP (JSON)
go func() {
ctx, cancel := context.WithCancel(root)
defer cancel()
field := metrics.Field{Key: "transport", Value: "http"}
before := httptransport.BindingBefore(zipkin.ToContext(zipkinSpanFunc))
after := httptransport.BindingAfter(httptransport.SetContentType("application/json"))
makeRequest := func() interface{} { return &addRequest{} }
var handler http.Handler
handler = httptransport.NewBinding(ctx, makeRequest, jsoncodec.New(), e, before, after)
handler = encoding.Gzip(handler)
handler = cors.Middleware(cors.Config{})(handler)
handler = httpInstrument(requests.With(field), duration.With(field))(handler)
mux := http.NewServeMux()
mux.Handle("/add", handler)
logger.Log("addr", *httpAddr, "transport", "HTTP")
errc <- http.ListenAndServe(*httpAddr, mux)
}()
// Transport: gRPC
go func() {
ln, err := net.Listen("tcp", *grpcAddr)
if err != nil {
errc <- err
return
}
s := grpc.NewServer() // uses its own context?
field := metrics.Field{Key: "transport", Value: "grpc"}
var addServer pb.AddServer
addServer = grpcBinding{e}
addServer = grpcInstrument(requests.With(field), duration.With(field))(addServer)
pb.RegisterAddServer(s, addServer)
logger.Log("addr", *grpcAddr, "transport", "gRPC")
errc <- s.Serve(ln)
}()
// Transport: Thrift
go func() {
ctx, cancel := context.WithCancel(root)
defer cancel()
var protocolFactory thrift.TProtocolFactory
switch *thriftProtocol {
case "binary":
protocolFactory = thrift.NewTBinaryProtocolFactoryDefault()
case "compact":
protocolFactory = thrift.NewTCompactProtocolFactory()
case "json":
protocolFactory = thrift.NewTJSONProtocolFactory()
case "simplejson":
protocolFactory = thrift.NewTSimpleJSONProtocolFactory()
default:
errc <- fmt.Errorf("invalid Thrift protocol %q", *thriftProtocol)
return
}
var transportFactory thrift.TTransportFactory
if *thriftBufferSize > 0 {
transportFactory = thrift.NewTBufferedTransportFactory(*thriftBufferSize)
} else {
transportFactory = thrift.NewTTransportFactory()
}
if *thriftFramed {
transportFactory = thrift.NewTFramedTransportFactory(transportFactory)
}
transport, err := thrift.NewTServerSocket(*thriftAddr)
if err != nil {
errc <- err
return
}
field := metrics.Field{Key: "transport", Value: "thrift"}
var service thriftadd.AddService
service = thriftBinding{ctx, e}
service = thriftInstrument(requests.With(field), duration.With(field))(service)
logger.Log("addr", *thriftAddr, "transport", "Thrift")
errc <- thrift.NewTSimpleServer4(
thriftadd.NewAddServiceProcessor(service),
transport,
transportFactory,
protocolFactory,
).Serve()
}()
logger.Log("fatal", <-errc)
}
func TestHTTPClient(t *testing.T) {
var (
testbody = "testbody"
encode = func(context.Context, *http.Request, interface{}) error { return nil }
decode = func(_ context.Context, r *http.Response) (interface{}, error) {
buffer := make([]byte, len(testbody))
r.Body.Read(buffer)
return TestResponse{r.Body, string(buffer)}, nil
}
headers = make(chan string, 1)
headerKey = "X-Foo"
headerVal = "abcde"
afterHeaderKey = "X-The-Dude"
afterHeaderVal = "Abides"
afterVal = ""
afterFunc = func(ctx context.Context, r *http.Response) context.Context {
afterVal = r.Header.Get(afterHeaderKey)
return ctx
}
)
server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
headers <- r.Header.Get(headerKey)
w.Header().Set(afterHeaderKey, afterHeaderVal)
w.WriteHeader(http.StatusOK)
w.Write([]byte(testbody))
}))
client := httptransport.NewClient(
"GET",
mustParse(server.URL),
encode,
decode,
httptransport.ClientBefore(httptransport.SetRequestHeader(headerKey, headerVal)),
httptransport.ClientAfter(afterFunc),
)
res, err := client.Endpoint()(context.Background(), struct{}{})
if err != nil {
t.Fatal(err)
}
var have string
select {
case have = <-headers:
case <-time.After(time.Millisecond):
t.Fatalf("timeout waiting for %s", headerKey)
}
// Check that Request Header was successfully received
if want := headerVal; want != have {
t.Errorf("want %q, have %q", want, have)
}
// Check that Response header set from server was received in SetClientAfter
if want, have := afterVal, afterHeaderVal; want != have {
t.Errorf("want %q, have %q", want, have)
}
// Check that the response was successfully decoded
response, ok := res.(TestResponse)
if !ok {
t.Fatal("response should be TestResponse")
}
if want, have := testbody, response.String; want != have {
t.Errorf("want %q, have %q", want, have)
}
// Check that response body was closed
b := make([]byte, 1)
_, err = response.Body.Read(b)
if err == nil {
t.Fatal("wanted error, got none")
}
if doNotWant, have := io.EOF, err; doNotWant == have {
t.Errorf("do not want %q, have %q", doNotWant, have)
}
}