Make 'URLPathTransformer' interface and implementation to do the function prefix trimming instead of baking it in. Also add a configuration option, 'pass_url_path_to_functions' to control whether the full path is passed to the functions or not.

Signed-off-by: Thomas E Lackey <telackey@bozemanpass.com>

gateway/handlers/forwarding_proxy.go

@@ -29,12 +29,17 @@ type BaseURLResolver interface {
 	Resolve(r *http.Request) string
 }
 
+// RequestURLPathTransformer Transform the incoming URL path for upstream requests
+type URLPathTransformer interface {
+	Transform(r *http.Request) string
+}
+
 // MakeForwardingProxyHandler create a handler which forwards HTTP requests
-func MakeForwardingProxyHandler(proxy *types.HTTPClientReverseProxy, notifiers []HTTPNotifier, baseURLResolver BaseURLResolver) http.HandlerFunc {
+func MakeForwardingProxyHandler(proxy *types.HTTPClientReverseProxy, notifiers []HTTPNotifier, baseURLResolver BaseURLResolver, urlPathTransformer URLPathTransformer) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		baseURL := baseURLResolver.Resolve(r)
 
-		requestURL := r.URL.Path
+		requestURL := urlPathTransformer.Transform(r)
 
 		start := time.Now()
 
@@ -51,23 +56,7 @@ func MakeForwardingProxyHandler(proxy *types.HTTPClientReverseProxy, notifiers [
 }
 
 func buildUpstreamRequest(r *http.Request, baseURL string, requestURL string) *http.Request {
-	url := baseURL
-
-	if requestURL != "" {
-		// When forwarding to a function, since the `/function/xyz` portion
-		// of a path like `/function/xyz/rest/of/path` is only used or needed
-		// by the Gateway, we want to trim it down to `/rest/of/path` for the
-		// upstream request.  In the following regex, in the case of a match
-		// the requestURL will be at `0`, the function name at `1` and the
-		// rest of the path (the part we are interested in) at `2`.
-		matcher := functionMatcher.Copy()
-		parts := matcher.FindStringSubmatch(requestURL)
-		if 3 == len(parts) {
-			url += parts[2]
-		} else {
-			url += requestURL
-		}
-	}
+	url := baseURL + requestURL
 
 	if len(r.URL.RawQuery) > 0 {
 		url = fmt.Sprintf("%s?%s", url, r.URL.RawQuery)
@@ -211,3 +200,46 @@ func (f FunctionAsHostBaseURLResolver) Resolve(r *http.Request) string {
 
 	return fmt.Sprintf("http://%s%s:%d", svcName, suffix, watchdogPort)
 }
+
+// TransparentURLPathTransformer passes the requested URL path through untouched.
+type TransparentURLPathTransformer struct {
+}
+
+// Transform returns the URL path unchanged.
+func (f TransparentURLPathTransformer) Transform(r *http.Request) string {
+	return r.URL.Path
+}
+
+// PathTruncatingURLPathTransformer always truncated the path to "/".
+type PathTruncatingURLPathTransformer struct {
+}
+
+// Transform always return a path of "/".
+func (f PathTruncatingURLPathTransformer) Transform(r *http.Request) string {
+	return "/"
+}
+
+// FunctionPrefixTrimmingURLPathTransformer removes the "/function/servicename/" prefix from the URL path.
+type FunctionPrefixTrimmingURLPathTransformer struct {
+}
+
+// Transform removes the "/function/servicename/" prefix from the URL path.
+func (f FunctionPrefixTrimmingURLPathTransformer) Transform(r *http.Request) string {
+	ret := r.URL.Path
+
+	if ret != "" {
+		// When forwarding to a function, since the `/function/xyz` portion
+		// of a path like `/function/xyz/rest/of/path` is only used or needed
+		// by the Gateway, we want to trim it down to `/rest/of/path` for the
+		// upstream request.  In the following regex, in the case of a match
+		// the r.URL.Path will be at `0`, the function name at `1` and the
+		// rest of the path (the part we are interested in) at `2`.
+		matcher := functionMatcher.Copy()
+		parts := matcher.FindStringSubmatch(ret)
+		if 3 == len(parts) {
+			ret = parts[2]
+		}
+	}
+
+	return ret
+}

gateway/handlers/forwarding_proxy_test.go

@@ -164,7 +164,10 @@ func Test_buildUpstreamRequest_Body_Method_Query_Path(t *testing.T) {
 		t.Fail()
 	}
 
-	upstream := buildUpstreamRequest(request, "http://xyz:8080", request.URL.Path)
+	transformer := FunctionPrefixTrimmingURLPathTransformer{}
+	transformedPath := transformer.Transform(request)
+
+	upstream := buildUpstreamRequest(request, "http://xyz:8080", transformedPath)
 
 	if request.Method != upstream.Method {
 		t.Errorf("Method - want: %s, got: %s", request.Method, upstream.Method)

gateway/handlers/queueproxy.go

@@ -15,7 +15,7 @@ import (
 )
 
 // MakeQueuedProxy accepts work onto a queue
-func MakeQueuedProxy(metrics metrics.MetricOptions, wildcard bool, canQueueRequests queue.CanQueueRequests) http.HandlerFunc {
+func MakeQueuedProxy(metrics metrics.MetricOptions, wildcard bool, canQueueRequests queue.CanQueueRequests, pathTransformer URLPathTransformer) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 
@@ -49,6 +49,7 @@ func MakeQueuedProxy(metrics metrics.MetricOptions, wildcard bool, canQueueReque
 			Body:        body,
 			Method:      r.Method,
 			QueryString: r.URL.RawQuery,
+			Path:        pathTransformer.Transform(r),
 			Header:      r.Header,
 			Host:        r.Host,
 			CallbackURL: callbackURL,

gateway/queue/types.go

@@ -12,6 +12,7 @@ type Request struct {
 	Host        string
 	Body        []byte
 	Method      string
+	Path        string
 	QueryString string
 	Function    string
 	CallbackURL *url.URL `json:"CallbackUrl"`

gateway/server.go

@@ -74,14 +74,23 @@ func main() {
 		functionURLResolver = urlResolver
 	}
 
-	faasHandlers.Proxy = handlers.MakeForwardingProxyHandler(reverseProxy, functionNotifiers, functionURLResolver)
+	urlTransformer := handlers.PathTruncatingURLPathTransformer{}
+	var functionURLTransformer handlers.URLPathTransformer
 
-	faasHandlers.RoutelessProxy = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
-	faasHandlers.ListFunctions = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
-	faasHandlers.DeployFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
-	faasHandlers.DeleteFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
-	faasHandlers.UpdateFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
-	queryFunction := handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
+	if config.PassURLPathsToFunctions {
+		functionURLTransformer = handlers.FunctionPrefixTrimmingURLPathTransformer{}
+	} else {
+		functionURLTransformer = urlTransformer
+	}
+
+	faasHandlers.Proxy = handlers.MakeForwardingProxyHandler(reverseProxy, functionNotifiers, functionURLResolver, functionURLTransformer)
+
+	faasHandlers.RoutelessProxy = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
+	faasHandlers.ListFunctions = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
+	faasHandlers.DeployFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
+	faasHandlers.DeleteFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
+	faasHandlers.UpdateFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
+	queryFunction := handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
 
 	alertHandler := plugin.NewExternalServiceQuery(*config.FunctionsProviderURL)
 	faasHandlers.Alert = handlers.MakeAlertHandler(alertHandler)
@@ -93,7 +102,7 @@ func main() {
 			log.Fatalln(queueErr)
 		}
 
-		faasHandlers.QueuedProxy = handlers.MakeCallIDMiddleware(handlers.MakeQueuedProxy(metricsOptions, true, natsQueue))
+		faasHandlers.QueuedProxy = handlers.MakeCallIDMiddleware(handlers.MakeQueuedProxy(metricsOptions, true, natsQueue, functionURLTransformer))
 		faasHandlers.AsyncReport = handlers.MakeAsyncReport(metricsOptions)
 	}
 
@@ -101,7 +110,7 @@ func main() {
 	faasHandlers.ListFunctions = metrics.AddMetricsHandler(faasHandlers.ListFunctions, prometheusQuery)
 	faasHandlers.Proxy = handlers.MakeCallIDMiddleware(faasHandlers.Proxy)
 
-	faasHandlers.ScaleFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)
+	faasHandlers.ScaleFunction = handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)
 
 	if credentials != nil {
 		faasHandlers.UpdateFunction =
@@ -135,10 +144,10 @@ func main() {
 	// r.StrictSlash(false)	// This didn't work, so register routes twice.
 	r.HandleFunc("/function/{name:[-a-zA-Z_0-9]+}", functionProxy)
 	r.HandleFunc("/function/{name:[-a-zA-Z_0-9]+}/", functionProxy)
-	r.HandleFunc("/function/{name:[-a-zA-Z_0-9]+}/{params:.*}", faasHandlers.Proxy)
+	r.HandleFunc("/function/{name:[-a-zA-Z_0-9]+}/{params:.*}", functionProxy)
 
 	r.HandleFunc("/system/info", handlers.MakeInfoHandler(handlers.MakeForwardingProxyHandler(
-		reverseProxy, forwardingNotifiers, urlResolver))).Methods(http.MethodGet)
+		reverseProxy, forwardingNotifiers, urlResolver, urlTransformer))).Methods(http.MethodGet)
 
 	r.HandleFunc("/system/alert", faasHandlers.Alert)
 
@@ -172,7 +181,7 @@ func main() {
 
 	metricsHandler := metrics.PrometheusHandler()
 	r.Handle("/metrics", metricsHandler)
-	r.HandleFunc("/healthz", handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver)).Methods(http.MethodGet)
+	r.HandleFunc("/healthz", handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, urlTransformer)).Methods(http.MethodGet)
 
 	r.Handle("/", http.RedirectHandler("/ui/", http.StatusMovedPermanently)).Methods(http.MethodGet)
 

gateway/types/readconfig.go

@@ -105,6 +105,8 @@ func (ReadConfig) Read(hasEnv HasEnv) GatewayConfig {
 	cfg.DirectFunctions = parseBoolValue(hasEnv.Getenv("direct_functions"))
 	cfg.DirectFunctionsSuffix = hasEnv.Getenv("direct_functions_suffix")
 
+	cfg.PassURLPathsToFunctions = parseBoolValue(hasEnv.Getenv("pass_url_path_to_functions"))
+
 	cfg.UseBasicAuth = parseBoolValue(hasEnv.Getenv("basic_auth"))
 
 	secretPath := hasEnv.Getenv("secret_mount_path")
@@ -150,6 +152,10 @@ type GatewayConfig struct {
 	// If set this will be used to resolve functions directly
 	DirectFunctionsSuffix string
 
+	// If set to true, the requested path will be passed along to the function, minus the "/function/xyz"
+	// prefix, else the path will be truncated to "/" regardless of what the client sends.
+	PassURLPathsToFunctions bool
+
 	// If set, reads secrets from file-system for enabling basic auth.
 	UseBasicAuth bool