HTTP Handler for functions

The function handler will be the handler for each http trigger.  It
will look up the function service map to find a service for the
function (and call the pool manager to create a new service if one
doesn't already exist, though this isn't implemented yet).  It'll then
proxy the request to the service.

src/router/functionHandler.go

@@ -0,0 +1,70 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package router
+
+import (
+	"log"
+	"net/http"
+	"net/http/httputil"
+	"errors"
+	"net/url"
+)
+
+type functionHandler struct {
+	fmap *functionServiceMap
+	function
+}
+
+func getService(f *function) (*url.URL, error) {
+	return nil, errors.New("not implemented")
+}
+
+func (fh *functionHandler) handler(responseWriter http.ResponseWriter, request *http.Request) {
+	serviceUrl, err := fh.fmap.lookup(&fh.function)
+	if (err != nil) {
+		// Cache miss: request the Pool Manager to make a new service.
+		serviceUrl, poolErr := getService(&fh.function)
+		if (poolErr != nil) {
+			// now we're really screwed
+			log.Printf("Failed to get service for function (%v,%v): %v",
+				fh.function.name, fh.function.uid, poolErr);
+			responseWriter.WriteHeader(500) // TODO: make this smarter based on the actual error
+			return
+		}
+
+		// add it to the map
+		fh.fmap.assign(&fh.function, serviceUrl)
+	}
+
+	// Proxy off our request to the serviceUrl, and send the response back.
+	// TODO: As an optimization we may want to cache proxies too -- this would get us
+	// connection reuse and possibly better performance
+	director := func(req *http.Request) {	
+		// send this request to serviceurl
+		req.URL.Scheme = serviceUrl.Scheme
+		req.URL.Host = serviceUrl.Host
+		req.URL.Path = serviceUrl.Path
+		// leave the query string intact (req.URL.RawQuery)
+
+		if _, ok := req.Header["User-Agent"]; !ok {
+			// explicitly disable User-Agent so it's not set to default value
+			req.Header.Set("User-Agent", "")
+		}
+	}
+	proxy := &httputil.ReverseProxy{Director: director}
+	proxy.ServeHTTP(responseWriter, request)
+}

src/router/functionHandler_test.go

@@ -0,0 +1,61 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package router
+
+import (
+	"log"
+	"testing"
+	"net/http"
+//	"net/http/httputil"
+	"net/http/httptest"
+	"net/url"
+)
+
+
+func createBackendService(testResponseString string) *url.URL {
+	backendServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(testResponseString))
+	}))
+
+	backendURL, err := url.Parse(backendServer.URL)
+	if err != nil {
+		panic("error parsing url")
+	}
+	return backendURL
+}
+
+/*
+    1. Create a service at some URL
+    2. Add it to the function service map
+    3. Create a http server with some trigger url pointed at function handler
+    4. Send a request to that server, ensure it reaches the first service.
+*/
+func TestFunctionProxying(t *testing.T) {
+	testResponseString := "hi"
+	backendURL := createBackendService(testResponseString)
+	log.Printf("Created backend svc at %v", backendURL)
+
+	fn := &function{name: "foo", uid: "xxx"}	
+	fmap := makeFunctionServiceMap()
+	fmap.assign(fn, backendURL)
+	
+	fh := &functionHandler{fmap: fmap, function: *fn}
+	functionHandlerServer := httptest.NewServer(http.HandlerFunc(fh.handler))
+	fhURL := functionHandlerServer.URL
+	
+	testRequest(fhURL, testResponseString)
+}

src/router/router.go

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+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/*
+
+This is the Fission Router package.
+
+Its job is to:
+
+  1. Keep track of HTTP triggers and their mappings to functions
+
+     Use the controller API to get and watch this state.
+  
+  2. Given a function, get a reference to a routable function run service
+
+     Use the ContainerPoolManager API to get a service backed by one
+     or more function run containers.  The container(s) backing the
+     service may be newly created, or they might be reused.  The only
+     requirement is that one or more containers backs the service.
+
+  3. Forward the request to the service, and send the response back.
+
+     Plain ol HTTP.
+
+*/
+
+
+package router
+
+import (
+//	"fmt"
+//	"net/http"
+)
+
+type (
+	function struct {
+		name string
+		uid string
+	}
+	
+	httptrigger struct {
+		urlPattern string
+		function
+	}
+
+	options struct {
+		port int
+		poolManagerUrl string
+		//...
+	}
+	
+)
+
+// request url ---[trigger]---> function(name,uid) ----[pool mgr]----> k8s service url
+
+// request url ---[trigger]---> function(name, deployment) ----[deployment]----> function(name, uid) ----[pool mgr]---> k8s service url
+