Chainable HTTP client middleware. Borrowed from OkHttp.
Interceptors monitor outgoing requests, and incoming responses. Here's an interceptor that logs all requests made and responses received by the client.
import "github.com/f2prateek/train"
f := func(chain train.Chain) (*http.Response, error) {
req := chain.Request()
fmt.Println(httputil.DumpRequestOut(req, false))
resp, err := chain.Proceed(req)
fmt.Println(httputil.DumpRequestOut(req, false))
return resp, err
})
transport := train.Transport(train.InterceptorFunc(f))
client := &http.Client{
Transport: transport,
}
client.Get("https://golang.org")
// Output:
// GET / HTTP/1.1
// Host: 127.0.0.1:64598
//
// HTTP/1.1 200 OK
// Content-Length: 13
// Content-Type: text/plain; charset=utf-8
// Date: Thu, 25 Feb 2016 09:49:28 GMTInterceptors may modify requests and responses.
func Intercept(chain train.Chain) (*http.Response, error) {
req := chain.Request()
req.Header.Add("User-Agent", "Train Example")
resp, err := chain.Proceed(req)
resp.Header.Add("Cache-Control", "max-age=60")
return resp, err
})Or interceptors can simply short circuit the chain.
func Intercept(train.Chain) (*http.Response, error) {
return cannedResponse, cannedError
})Train chains interceptors so that they can be plugged into any http.Client. For example, this chain will transparently, retry requests for temporary errors, log requests/responses and increment some request/response stats.
import "github.com/f2prateek/log"
import "github.com/f2prateek/statsd"
import "github.com/f2prateek/hickson"
import "github.com/f2prateek/hickson/temporary"
errInterceptor := hickson.New(hickson.RetryMax(5, temporary.RetryErrors()))
logInterceptor := log.New(os.Stdout, log.Body)
statsInterceptor := statsd.New(statsdClient)
transport := train.Transport(errInterceptor, logInterceptor, statsInterceptor)
client := &http.Client{
Transport: transport,
}
client.Get("https://golang.org")Interceptors are consulted in the order they are provided. You'll need to decide what order you want your interceptors to be called in.
// This chain will:
// 1. Start monitoring errors.
// 2. Log the request.
// 3. Record stats about the request.
// 4. Do HTTP.
// 5. Record stats about the response.
// 6. Log the response.
// 7. Retry temporary errors, if any, and restart the chain at 2 in that case.
transport := train.Transport(errInterceptor, logInterceptor, statsInterceptor)
// This chain will:
// 1. Log the request.
// 2. Record stats about the request.
// 3. Do HTTP.
// 4. Retry temporary errors and return after all retries have been exhausted.
// 5. Record stats about the response.
// 6. Log the response.
transport := train.Transport(logInterceptor, statsInterceptor, errInterceptor)