Merge pull request #1 from JSainsburyPLC/feature/rewrite-rules

Support nginx style URL rewrites

Author: steinfletcher

.gitignore

@@ -1,2 +1,3 @@
 ui-dev-proxy
 dist/
+.sequence/

README.md

@@ -43,7 +43,10 @@ See `examples/config.json`
 {
   "type": "proxy", // Required
   "path_pattern": "^/test-ui/.*", // regex to match request path. Required
-  "backend": "http://localhost:3000" // backend scheme and host to proxy to. Required
+  "backend": "http://localhost:3000", // backend scheme and host to proxy to. Required
+  "rewrite": { // optional rewrite rules
+    "/test-ui/(.*)": "/$1"
+  }
 }
 ```
 

commands/start.go

@@ -2,7 +2,7 @@ package commands
 
 import (
 	"github.com/JSainsburyPLC/ui-dev-proxy/domain"
-	"github.com/JSainsburyPLC/ui-dev-proxy/proxy"
+	"github.com/JSainsburyPLC/ui-dev-proxy/http/proxy"
 	"github.com/urfave/cli"
 	"log"
 	"net/url"

domain/config.go

@@ -16,10 +16,11 @@ type Config struct {
 }
 
 type Route struct {
-	Type        string       `json:"type"`
-	PathPattern *PathPattern `json:"path_pattern"`
-	Backend     *Backend     `json:"backend"`
-	Mock        *Mock        `json:"mock"`
+	Type        string            `json:"type"`
+	PathPattern *PathPattern      `json:"path_pattern"`
+	Backend     *Backend          `json:"backend"`
+	Mock        *Mock             `json:"mock"`
+	Rewrite     map[string]string `json:"rewrite"`
 }
 
 type PathPattern struct {

go.mod

@@ -1,11 +1,9 @@
 module github.com/JSainsburyPLC/ui-dev-proxy
 
-go 1.12
+go 1.13
 
 require (
-	github.com/steinfletcher/apitest v1.3.8
-	github.com/stretchr/objx v0.2.0 // indirect
+	github.com/steinfletcher/apitest v1.3.13
 	github.com/stretchr/testify v1.4.0
 	github.com/urfave/cli v1.22.1
-	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 )

go.sum

@@ -3,24 +3,20 @@ github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSY
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday/v2 v2.0.1 h1:lPqVAte+HuHNfhJ/0LC98ESWRz8afy9tM/0RK8m9o+Q=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
-github.com/steinfletcher/apitest v1.3.8 h1:Q5CrFWbXSo9ocx9pb0IgPw38FKPKfkfEF+3+V35n4M8=
-github.com/steinfletcher/apitest v1.3.8/go.mod h1:LOVbGzWvWCiiVE4PZByfhRnA5L00l5uZQEx403xQ4K8=
+github.com/steinfletcher/apitest v1.3.13 h1:E0BAXde9dke8jEjK1hqTGvmI20vyyfC+xSdE9nmTc84=
+github.com/steinfletcher/apitest v1.3.13/go.mod h1:pCHKMM2TcH1pezw/xbmilaCdK9/dGsoCZBafwaqJ2sY=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/objx v0.2.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoHMkEqE=
-github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/urfave/cli v1.22.1 h1:+mkCCcOFKPnCmVYVcURKps1Xe+3zP90gSYGNfRkjoIY=
 github.com/urfave/cli v1.22.1/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

proxy/proxy.go renamed to http/proxy/proxy.go

@@ -6,6 +6,8 @@ import (
 	"errors"
 	"fmt"
 	"github.com/JSainsburyPLC/ui-dev-proxy/domain"
+	"github.com/JSainsburyPLC/ui-dev-proxy/http/rewrite"
+
 	"log"
 	"net/http"
 	"net/http/httputil"
@@ -30,7 +32,7 @@ func NewProxy(
 	logger *log.Logger,
 ) *Proxy {
 	reverseProxy := &httputil.ReverseProxy{
-		Director:     director(defaultBackend),
+		Director:     director(defaultBackend, logger),
 		ErrorHandler: errorHandler(logger),
 	}
 	return &Proxy{
@@ -56,7 +58,7 @@ func (p *Proxy) Start() {
 	}
 }
 
-func director(defaultBackend *url.URL) func(req *http.Request) {
+func director(defaultBackend *url.URL, logger *log.Logger) func(req *http.Request) {
 	return func(req *http.Request) {
 		route, ok := req.Context().Value(routeCtxKey).(*domain.Route)
 		if !ok {
@@ -70,6 +72,26 @@ func director(defaultBackend *url.URL) func(req *http.Request) {
 		req.URL.Scheme = route.Backend.Scheme
 		req.URL.Host = route.Backend.Host
 		req.Host = route.Backend.Host
+
+		// apply any defined rewrite rules
+		for pattern, to := range route.Rewrite {
+			rule, err := rewrite.NewRule(pattern, to)
+			if err != nil {
+				logger.Println(fmt.Sprintf("error creating rewrite rule. %v", err))
+				continue
+			}
+
+			matched, err := rule.Rewrite(req)
+			if err != nil {
+				logger.Println(fmt.Sprintf("failed to rewrite request. %v", err))
+				continue
+			}
+
+			// recursive rewrites are not supported, exit on first rewrite
+			if matched {
+				break
+			}
+		}
 	}
 }
 

proxy/proxy_test.go renamed to http/proxy/proxy_test.go

@@ -61,6 +61,23 @@ func TestProxy_ProxyBackend_UserProxy_Success(t *testing.T) {
 		End()
 }
 
+func TestProxy_ProxyBackend_RewriteURL(t *testing.T) {
+	newApiTest(configWithRewrite(map[string]string{
+		"/test-ui/(.*)": "/rewrite-ui/$1",
+	}), "http://test-backend", false).
+		Mocks(apitest.NewMock().
+			Get("http://localhost:3001/rewrite-ui/users/info").
+			RespondWith().
+			Status(http.StatusOK).
+			Body(`{"user_id": "123"}`).
+			End()).
+		Get("/test-ui/users/info").
+		Expect(t).
+		Status(http.StatusOK).
+		Body(`{"user_id": "123"}`).
+		End()
+}
+
 func TestProxy_MockBackend_Failure(t *testing.T) {
 	newApiTest(config(), "http://test-backend", false).
 		Mocks(
@@ -194,6 +211,12 @@ func config() domain.Config {
 	}
 }
 
+func configWithRewrite(rewrite map[string]string) domain.Config {
+	conf := config()
+	conf.Routes[0].Rewrite = rewrite
+	return conf
+}
+
 func invalidTypeConfig() domain.Config {
 	mockProxyUrlUserUi, err := url.Parse("http://localhost:3001")
 	if err != nil {

http/rewrite/rewrite.go

@@ -0,0 +1,58 @@
+package rewrite
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"regexp"
+)
+
+type Rule struct {
+	pattern string
+	to      string
+	regexp  *regexp.Regexp
+}
+
+func NewRule(pattern, to string) (Rule, error) {
+	reg, err := regexp.Compile(pattern)
+	if err != nil {
+		return Rule{}, err
+	}
+
+	return Rule{
+		pattern: pattern,
+		to:      to,
+		regexp:  reg,
+	}, nil
+}
+
+func (r *Rule) Rewrite(req *http.Request) (bool, error) {
+	oriPath := req.URL.Path
+
+	if !r.regexp.MatchString(oriPath) {
+		return false, nil
+	}
+
+	to := path.Clean(r.Replace(req.URL))
+	u, e := url.Parse(to)
+	if e != nil {
+		return false, fmt.Errorf("rewritten URL is not valid. %w", e)
+	}
+
+	req.URL.Path = u.Path
+	req.URL.RawPath = u.RawPath
+	if u.RawQuery != "" {
+		req.URL.RawQuery = u.RawQuery
+	}
+
+	return true, nil
+}
+
+func (r *Rule) Replace(u *url.URL) string {
+	uri := u.RequestURI()
+	patternRegexp := regexp.MustCompile(r.pattern)
+	match := patternRegexp.FindStringSubmatchIndex(uri)
+	result := patternRegexp.ExpandString([]byte(""), r.to, uri, match)
+	return string(result[:])
+}

http/rewrite/rewrite_test.go

@@ -0,0 +1,73 @@
+package rewrite_test
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/JSainsburyPLC/ui-dev-proxy/http/rewrite"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRewrite(t *testing.T) {
+	tests := map[string]struct {
+		pattern string
+		to      string
+		before  string
+		after   string
+		matched bool
+	}{
+		"constant": {
+			pattern: "/a",
+			to:      "/b",
+			before:  "/a",
+			after:   "/b",
+			matched: true,
+		},
+		"preserves original URL if no match": {
+			pattern: "/a",
+			to:      "/b",
+			before:  "/c",
+			after:   "/c",
+			matched: false,
+		},
+		"match group": {
+			pattern: "/api/(.*)",
+			to:      "/$1",
+			before:  "/api/my-endpoint",
+			after:   "/my-endpoint",
+			matched: true,
+		},
+		"multiple match groups": {
+			pattern: "/a/(.*)/b/(.*)",
+			to:      "/x/y/$1/z/$2",
+			before:  "/a/oo/b/qq",
+			after:   "/x/y/oo/z/qq",
+			matched: true,
+		},
+		"encoded characters": {
+			pattern: "/a/(.*)",
+			to:      "/b/$1",
+			before:  "/a/x-1%2F",
+			after:   "/b/x-1%2F",
+			matched: true,
+		},
+	}
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			req, err := http.NewRequest("GET", test.before, nil)
+			if err != nil {
+				t.Fatalf("failed to create request %v %v", test, err)
+			}
+			rule, err := rewrite.NewRule(test.pattern, test.to)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			matched, err := rule.Rewrite(req)
+
+			assert.NoError(t, err)
+			assert.Equal(t, test.after, req.URL.EscapedPath())
+			assert.Equal(t, test.matched, matched)
+		})
+	}
+}