Merge pull request #12 from JSainsburyPLC/fix/localhost-links

Change links to point to localhost on local dev

Author: msachi

domain/config.go

@@ -17,14 +17,15 @@ type Config struct {
 }
 
 type Route struct {
-	Type                 string            `json:"type"`
-	PathPattern          *PathPattern      `json:"path_pattern"`
-	Backend              *Backend          `json:"backend"`
-	Mock                 *Mock             `json:"mock"`
-	Rewrite              []Rewrite         `json:"rewrite"`
-	Redirect             *Redirect         `json:"redirect"`
-	ProxyPassHeaders     map[string]string `json:"proxy_pass_headers"`
-	ProxyResponseHeaders map[string]string `json:"proxy_response_headers"`
+	Type                      string            `json:"type"`
+	PathPattern               *PathPattern      `json:"path_pattern"`
+	Backend                   *Backend          `json:"backend"`
+	Mock                      *Mock             `json:"mock"`
+	Rewrite                   []Rewrite         `json:"rewrite"`
+	Redirect                  *Redirect         `json:"redirect"`
+	ProxyPassHeaders          map[string]string `json:"proxy_pass_headers"`
+	ProxyResponseHeaders      map[string]string `json:"proxy_response_headers"`
+	ProxyResponseReplacements map[string]string `json:"proxy_response_replacements"`
 }
 
 type Rewrite struct {

proxy/proxy.go

@@ -1,15 +1,20 @@
 package proxy
 
 import (
+	"bytes"
+	"compress/gzip"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 	"path"
+	"strings"
 	"time"
 
 	"github.com/JSainsburyPLC/ui-dev-proxy/domain"
@@ -93,6 +98,44 @@ func director(defaultBackend *url.URL, logger *log.Logger) func(req *http.Reques
 	}
 }
 
+func gUnzipData(data []byte) ([]byte, error) {
+	b := bytes.NewBuffer(data)
+
+	var r io.Reader
+	r, err := gzip.NewReader(b)
+	if err != nil {
+		return nil, err
+	}
+
+	var resB bytes.Buffer
+	_, err = resB.ReadFrom(r)
+	if err != nil {
+		return nil, err
+	}
+
+	return resB.Bytes(), nil
+}
+
+func gZipData(data []byte) ([]byte, error) {
+	var b bytes.Buffer
+	gz := gzip.NewWriter(&b)
+
+	_, err := gz.Write(data)
+	if err != nil {
+		return nil, err
+	}
+
+	if err = gz.Flush(); err != nil {
+		return nil, err
+	}
+
+	if err = gz.Close(); err != nil {
+		return nil, err
+	}
+
+	return b.Bytes(), nil
+}
+
 func modifyResponse() func(*http.Response) error {
 	return func(res *http.Response) error {
 		route, ok := res.Request.Context().Value(routeCtxKey).(*domain.Route)
@@ -105,6 +148,48 @@ func modifyResponse() func(*http.Response) error {
 			res.Header.Set(k, v)
 		}
 
+		if len(route.ProxyResponseReplacements) != 0 {
+
+			bodyBytes, err := ioutil.ReadAll(res.Body)
+			if err != nil {
+				return err
+			}
+
+			isGZipped := http.DetectContentType(bodyBytes) == "application/x-gzip"
+
+			if isGZipped {
+				bodyBytes, err = gUnzipData(bodyBytes)
+				if err != nil {
+					return err
+				}
+			}
+
+			bodyString := string(bodyBytes)
+
+			for k, v := range route.ProxyResponseReplacements {
+				bodyString = strings.ReplaceAll(bodyString, k, v)
+
+				for headerKey, headerValues := range res.Header {
+					res.Header.Del(headerKey)
+					for _, headerValue := range headerValues {
+						res.Header.Add(headerKey, strings.ReplaceAll(headerValue, k, v))
+					}
+				}
+			}
+
+			bodyBytes = []byte(bodyString)
+
+			if isGZipped {
+				bodyBytes, err = gZipData(bodyBytes)
+				if err != nil {
+					return err
+				}
+			}
+
+			res.Header.Set("content-length", fmt.Sprintf("%d", len(bodyBytes)))
+			res.Body = ioutil.NopCloser(bytes.NewBuffer(bodyBytes))
+		}
+
 		return nil
 	}
 }

proxy/proxy_test.go

@@ -63,6 +63,24 @@ func TestProxy_ProxyBackend_UserProxy_Success(t *testing.T) {
 		End()
 }
 
+func TestProxy_ProxyBackend_ResponseReplacements(t *testing.T) {
+	backendMock := apitest.NewMock().Get("http://localhost:3001/test-ui/users/info").
+		RespondWith().
+		Status(http.StatusOK).
+		Header("test-header", "test-value-1").
+		Body(`{"product_id": "test-value-1"}`).
+		End()
+
+	newApiTest(config(), "http://test-backend", false).
+		Mocks(backendMock).
+		Get("/test-ui/users/info").
+		Expect(t).
+		Status(http.StatusOK).
+		Header("test-header", "test-value-2").
+		Body(`{"product_id": "test-value-2"}`).
+		End()
+}
+
 func TestProxy_Rewrite(t *testing.T) {
 	tests := map[string]struct {
 		pattern string
@@ -335,6 +353,9 @@ func config() domain.Config {
 				ProxyResponseHeaders: map[string]string{
 					"Cache-Control": "no-cache",
 				},
+				ProxyResponseReplacements: map[string]string{
+					"test-value-1": "test-value-2",
+				},
 			},
 			{
 				Type:        "proxy",