(feat): http request logging

dm/client.go

@@ -22,6 +22,8 @@ type Client struct {
 	Host string
 	// The protocol. Currently only http and https are supported.
 	Protocol string
+	// Transport
+	Transport http.RoundTripper
 }
 
 // NewClient creates a new DM client. Host name is required.
@@ -30,6 +32,7 @@ func NewClient(host string) *Client {
 		HTTPTimeout: DefaultHTTPTimeout,
 		Protocol:    "https",
 		Host:        host,
+		Transport:   NewDebugTransport(nil),
 	}
 }
 
@@ -71,6 +74,7 @@ func (c *Client) callHttp(path, method, action string, reader io.ReadCloser) (st
 
 	client := http.Client{
 		Timeout:   time.Duration(time.Duration(DefaultHTTPTimeout) * time.Second),
+		Transport: c.Transport,
 	}
 
 	response, err := client.Do(request)

dm/transport.go

+package dm
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httputil"
+	"os"
+)
+
+type debugTransport struct {
+	// Writer is the logging destination
+	Writer io.Writer
+
+	http.RoundTripper
+}
+
+func NewDebugTransport(rt http.RoundTripper) http.RoundTripper {
+	return debugTransport{
+		RoundTripper: rt,
+		Writer:       os.Stderr,
+	}
+}
+
+func (tr debugTransport) CancelRequest(req *http.Request) {
+	type canceler interface {
+		CancelRequest(*http.Request)
+	}
+	if cr, ok := tr.transport().(canceler); ok {
+		cr.CancelRequest(req)
+	}
+}
+
+func (tr debugTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	tr.logRequest(req)
+	resp, err := tr.transport().RoundTrip(req)
+	if err != nil {
+		return nil, err
+	}
+	tr.logResponse(resp)
+	return resp, err
+}
+
+func (tr debugTransport) transport() http.RoundTripper {
+	if tr.RoundTripper != nil {
+		return tr.RoundTripper
+	}
+	return http.DefaultTransport
+}
+
+func (tr debugTransport) logRequest(req *http.Request) {
+	dump, err := httputil.DumpRequestOut(req, true)
+	if err != nil {
+		fmt.Fprintf(tr.Writer, "%s: %s\n", "could not dump request", err)
+	}
+	fmt.Fprint(tr.Writer, string(dump))
+}
+
+func (tr debugTransport) logResponse(resp *http.Response) {
+	dump, err := httputil.DumpResponse(resp, true)
+	if err != nil {
+		fmt.Fprintf(tr.Writer, "%s: %s\n", "could not dump response", err)
+	}
+	fmt.Fprint(tr.Writer, string(dump))
+}

dm/transport_test.go

+package dm
+
+import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestDebugTransport(t *testing.T) {
+	handler := func(w http.ResponseWriter, req *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"status":"awesome"}`))
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(handler))
+	defer server.Close()
+
+	var output bytes.Buffer
+
+	client := &http.Client{
+		Transport: debugTransport{
+			Writer: &output,
+		},
+	}
+
+	_, err := client.Get(server.URL)
+	if err != nil {
+		t.Fatal(err.Error())
+	}
+
+	expected := []string{
+		"GET / HTTP/1.1",
+		"Accept-Encoding: gzip",
+		"HTTP/1.1 200 OK",
+		"Content-Length: 20",
+		"Content-Type: application/json",
+		`{"status":"awesome"}`,
+	}
+	actual := output.String()
+
+	for _, match := range expected {
+		if !strings.Contains(actual, match) {
+			t.Errorf("Expected %s to contain %s", actual, match)
+		}
+	}
+}