// 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.SetClientBefore(opentracing.FromHTTPRequest(tracer, "Sum", 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.SetClientBefore(opentracing.FromHTTPRequest(tracer, "Concat", 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
}
// New returns an AddService backed by a gRPC client connection. It is the
// responsibility of the caller to dial, and later close, the connection.
func New(conn *grpc.ClientConn, tracer stdopentracing.Tracer, logger log.Logger) addsvc.Service {
// 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 = grpctransport.NewClient(
conn,
"Add",
"Sum",
addsvc.EncodeGRPCSumRequest,
addsvc.DecodeGRPCSumResponse,
pb.SumReply{},
grpctransport.ClientBefore(opentracing.FromGRPCRequest(tracer, "Sum", 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 = grpctransport.NewClient(
conn,
"Add",
"Concat",
addsvc.EncodeGRPCConcatRequest,
addsvc.DecodeGRPCConcatResponse,
pb.ConcatReply{},
grpctransport.ClientBefore(opentracing.FromGRPCRequest(tracer, "Concat", logger)),
).Endpoint()
concatEndpoint = opentracing.TraceClient(tracer, "Concat")(concatEndpoint)
concatEndpoint = limiter(concatEndpoint)
concatEndpoint = circuitbreaker.Gobreaker(gobreaker.NewCircuitBreaker(gobreaker.Settings{
Name: "Concat",
Timeout: 30 * time.Second,
}))(concatEndpoint)
}
return addsvc.Endpoints{
SumEndpoint: sumEndpoint,
ConcatEndpoint: concatEndpoint,
}
}
func TestTraceClient(t *testing.T) {
tracer := mocktracer.New()
// Initialize the ctx with a parent Span.
parentSpan := tracer.StartSpan("parent").(*mocktracer.MockSpan)
defer parentSpan.Finish()
ctx := opentracing.ContextWithSpan(context.Background(), parentSpan)
tracedEndpoint := kitot.TraceClient(tracer, "testOp")(endpoint.Nop)
if _, err := tracedEndpoint(ctx, struct{}{}); err != nil {
t.Fatal(err)
}
// tracedEndpoint created a new Span.
finishedSpans := tracer.FinishedSpans()
if want, have := 1, len(finishedSpans); want != have {
t.Fatalf("Want %v span(s), found %v", want, have)
}
endpointSpan := finishedSpans[0]
if want, have := "testOp", endpointSpan.OperationName; want != have {
t.Fatalf("Want %q, have %q", want, have)
}
parentContext := parentSpan.Context().(mocktracer.MockSpanContext)
endpointContext := parentSpan.Context().(mocktracer.MockSpanContext)
// ... and that the parent ID is set appropriately.
if want, have := parentContext.SpanID, endpointContext.SpanID; want != have {
t.Errorf("Want ParentID %q, have %q", want, have)
}
}
func TestTraceClientNoContextSpan(t *testing.T) {
tracer := mocktracer.New()
// Empty/background context.
tracedEndpoint := kitot.TraceClient(tracer, "testOp")(endpoint.Nop)
if _, err := tracedEndpoint(context.Background(), struct{}{}); err != nil {
t.Fatal(err)
}
// tracedEndpoint created a new Span.
finishedSpans := tracer.FinishedSpans()
if want, have := 1, len(finishedSpans); want != have {
t.Fatalf("Want %v span(s), found %v", want, have)
}
endpointSpan := finishedSpans[0]
if want, have := "testOp", endpointSpan.OperationName; want != have {
t.Fatalf("Want %q, have %q", want, have)
}
}
func buildEndpoint(tracer opentracing.Tracer, operationName string, instances []string, factory loadbalancer.Factory, seed int64, logger log.Logger) endpoint.Endpoint {
publisher := static.NewPublisher(instances, factory, logger)
random := loadbalancer.NewRandom(publisher, seed)
endpoint := loadbalancer.Retry(10, 10*time.Second, random)
return kitot.TraceClient(tracer, operationName)(endpoint)
}