// 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
}
// MakeConcatEndpointFactory generates a Factory that transforms an http url
// into an Endpoint.
//
// The path of the url is reset to /concat.
func MakeConcatEndpointFactory(tracer opentracing.Tracer, tracingLogger log.Logger) loadbalancer.Factory {
return func(instance string) (endpoint.Endpoint, io.Closer, error) {
concatURL, err := url.Parse(instance)
if err != nil {
return nil, nil, err
}
concatURL.Path = "/concat"
client := httptransport.NewClient(
"GET",
concatURL,
server.EncodeConcatRequest,
server.DecodeConcatResponse,
httptransport.SetClient(nil),
httptransport.SetClientBefore(kitot.ToHTTPRequest(tracer, tracingLogger)),
)
return client.Endpoint(), nil, nil
}
}
func TestHTTPClient(t *testing.T) {
var (
encode = func(*http.Request, interface{}) error { return nil }
decode = func(*http.Response) (interface{}, error) { return struct{}{}, nil }
headers = make(chan string, 1)
headerKey = "X-Foo"
headerVal = "abcde"
)
server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
headers <- r.Header.Get(headerKey)
w.WriteHeader(http.StatusOK)
}))
client := httptransport.NewClient(
"GET",
mustParse(server.URL),
encode,
decode,
httptransport.SetClientBefore(httptransport.SetRequestHeader(headerKey, headerVal)),
)
_, 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)
}
if want := headerVal; want != have {
t.Errorf("want %q, have %q", want, have)
}
}
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"
)
server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
headers <- r.Header.Get(headerKey)
w.WriteHeader(http.StatusOK)
w.Write([]byte(testbody))
}))
client := httptransport.NewClient(
"GET",
mustParse(server.URL),
encode,
decode,
httptransport.SetClientBefore(httptransport.SetRequestHeader(headerKey, headerVal)),
)
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 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)
}
}