add support for HTTP response object. Closes #245

README.md

@@ -253,7 +253,7 @@ All data that passes through the Event Gateway is formatted as an Event, based o
 - `event` - `string` - the event name
 - `id` - `string` - the event's instance universally unique ID (provided by the event gateway)
 - `receivedAt` - `number` - the time (milliseconds) when the Event was received by the Event Gateway (provided by the event gateway)
-- `data` - type depends on `encoding` - the event payload
+- `data` - type depends on `dataType` - the event payload
 - `dataType` - `string` - the mime type of `data` payload
 
 Example:
@@ -268,25 +268,25 @@ Example:
 }
 ```
 
-### Event Data Types
+#### Event Data Type
 
-The MIME type of the data block can be specified using the Content-Type header. This allows the event gateway to understand how to deserialize the data block if it needs to. If not specified `application/octet-stream` type is assumed and no deserialization happens. In case of `application/json` encoding the event gateway passes deserialized JSON payload to target functions.
+The MIME type of the data block can be specified using the `Content-Type` header (by default it's `application/octet-stream`). This allows the event gateway to understand how to deserialize the data block if it needs to. In case of `application/json` type the event gateway passes JSON payload to the target functions. In any other case the data block is Base64 encoded.
 
 ### Emit a Custom Event (Async Function Invocation)
 
-`POST /` with `Event` header set to event name. Optionally `Content-Type: <MIME type>` header can be set to specify payload encoding.
+`POST /` with `Event` header set to an event name. Optionally `Content-Type: <MIME type>` header can be set to specify payload encoding.
 
 Request: arbitrary payload, subscribed function receives an event in above schema, where request payload is passed as `data` field
 
 Response: `202 Accepted` in case of success
 
-### Emit a HTTP Event
+### Emit an HTTP Event
 
-Creating HTTP subscription requires `method` and `path` properties. Those properties are used to emit HTTP event.
+Creating HTTP subscription requires `method` and `path` properties. Those properties are used to listen for HTTP events.
 
 `<method> /<path>`
 
-Request: arbitrary payload, subscribed function receives an event in above schema. `data` field has following fields:
+Request: arbitrary payload, subscribed function receives an event in above schema. `data` field has the following fields:
 
 ```
 {
@@ -304,6 +304,16 @@ Request: arbitrary payload, subscribed function receives an event in above schem
 
 Response: function response
 
+### Respond to an HTTP Event
+
+To respond to an HTTP event a function needs to return object with following fields:
+
+- `statusCode` - `int` - response status code, default: 200
+- `headers` - `object` - response headers
+- `body` - `string` - response body
+
+Currently, the event gateway supports only string responses.
+
 ### Invoking a Registered Function (Sync Function Invocation)
 
 `POST /` with `Event` header set to `invoke` and `Function-ID` set to function ID.

router/event.go

@@ -39,6 +39,13 @@ type HTTPEvent struct {
 	Method  string              `json:"method"`
 }
 
+// HTTPResponse is a response schema returned by subscribed function in case of HTTP event.
+type HTTPResponse struct {
+	StatusCode int               `json:"statusCode"`
+	Headers    map[string]string `json:"headers"`
+	Body       string            `json:"body"`
+}
+
 const (
 	mimeJSON       = "application/json"
 	mimeOctetStrem = "application/octet-stream"

router/integration_test.go

@@ -26,23 +26,22 @@ import (
 	"github.com/serverless/event-gateway/internal/metrics"
 	"github.com/serverless/event-gateway/internal/sync"
 	"github.com/serverless/event-gateway/subscriptions"
+	"github.com/stretchr/testify/assert"
 	"go.uber.org/zap"
 )
 
 func TestMain(t *testing.T) {
 	etcd.Register()
 }
 
-func TestIntegrationSubscription(t *testing.T) {
+func TestIntegration_Subscription(t *testing.T) {
 	logCfg := zap.NewDevelopmentConfig()
 	logCfg.DisableStacktrace = true
 	log, _ := logCfg.Build()
-
 	kv, shutdownGuard := newTestEtcd()
 
 	testAPIServer := newConfigAPIServer(kv, log)
 	defer testAPIServer.Close()
-
 	router, testRouterServer := newTestRouterServer(kv, log)
 	defer testRouterServer.Close()
 	router.StartWorkers()
@@ -100,23 +99,19 @@ func TestIntegrationSubscription(t *testing.T) {
 	shutdownGuard.ShutdownAndWait()
 }
 
-func TestIntegrationHTTPSubscription(t *testing.T) {
+func TestIntegration_HTTPSubscription(t *testing.T) {
 	logCfg := zap.NewDevelopmentConfig()
 	logCfg.DisableStacktrace = true
 	log, _ := logCfg.Build()
-
 	kv, shutdownGuard := newTestEtcd()
 
 	testAPIServer := newConfigAPIServer(kv, log)
 	defer testAPIServer.Close()
-
 	router, testRouterServer := newTestRouterServer(kv, log)
 	defer testRouterServer.Close()
 
-	expected := "😸"
-
 	testTargetServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		fmt.Fprintf(w, expected)
+		fmt.Fprintf(w, "😸")
 	}))
 	defer testTargetServer.Close()
 
@@ -132,22 +127,68 @@ func TestIntegrationHTTPSubscription(t *testing.T) {
 	post(testAPIServer.URL+"/v1/subscriptions", subscriptions.Subscription{
 		FunctionID: functions.FunctionID("supersmileyfunction"),
 		Event:      "http",
-		Method:     "POST",
+		Method:     "GET",
 		Path:       "/smilez",
 	})
 
 	select {
-	case <-router.WaitForEndpoint(subscriptions.NewEndpointID("POST", "/smilez")):
+	case <-router.WaitForEndpoint(subscriptions.NewEndpointID("GET", "/smilez")):
 	case <-time.After(10 * time.Second):
 		panic("timed out waiting for endpoint to be configured!")
 	}
 
-	res := get(testRouterServer.URL + "/smilez")
+	_, _, body := get(testRouterServer.URL + "/smilez")
+	assert.Equal(t, "😸", body)
+
+	router.Drain()
+	shutdownGuard.ShutdownAndWait()
+}
+
+func TestIntegration_HTTPResponse(t *testing.T) {
+	logCfg := zap.NewDevelopmentConfig()
+	logCfg.DisableStacktrace = true
+	log, _ := logCfg.Build()
+
+	kv, shutdownGuard := newTestEtcd()
+
+	testAPIServer := newConfigAPIServer(kv, log)
+	defer testAPIServer.Close()
+
+	router, testRouterServer := newTestRouterServer(kv, log)
+	defer testRouterServer.Close()
+
+	testTargetServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, `{"statusCode":201,"headers":{"content-type":"text/html"},"body":"<head></head>"}`)
+	}))
+	defer testTargetServer.Close()
 
-	if res != expected {
-		panic("returned value was not \"" + expected + "\", unexpected value: \"" + res + "\"")
+	post(testAPIServer.URL+"/v1/functions",
+		functions.Function{
+			ID: functions.FunctionID("httpresponse"),
+			Provider: &functions.Provider{
+				Type: functions.HTTPEndpoint,
+				URL:  testTargetServer.URL,
+			},
+		})
+
+	post(testAPIServer.URL+"/v1/subscriptions", subscriptions.Subscription{
+		FunctionID: functions.FunctionID("httpresponse"),
+		Event:      "http",
+		Method:     "GET",
+		Path:       "/httpresponse",
+	})
+
+	select {
+	case <-router.WaitForEndpoint(subscriptions.NewEndpointID("GET", "/httpresponse")):
+	case <-time.After(10 * time.Second):
+		panic("timed out waiting for endpoint to be configured!")
 	}
 
+	statusCode, headers, body := get(testRouterServer.URL + "/httpresponse")
+	assert.Equal(t, statusCode, 201)
+	assert.Equal(t, headers.Get("content-type"), "text/html")
+	assert.Equal(t, body, "<head></head>")
+
 	router.Drain()
 	shutdownGuard.ShutdownAndWait()
 }
@@ -174,9 +215,9 @@ func emit(url, topic string, body []byte) {
 	defer resp.Body.Close()
 }
 
-func post(url string, thing interface{}) ([]byte, error) {
+func post(url string, payload interface{}) ([]byte, error) {
 	reqBytes := &bytes.Buffer{}
-	json.NewEncoder(reqBytes).Encode(thing)
+	json.NewEncoder(reqBytes).Encode(payload)
 
 	resp, err := http.Post(url, "application/json", reqBytes)
 	if err != nil {
@@ -187,8 +228,8 @@ func post(url string, thing interface{}) ([]byte, error) {
 	return ioutil.ReadAll(resp.Body)
 }
 
-func get(url string) string {
-	res, err := http.Post(url, "application/json", nil)
+func get(url string) (int, http.Header, string) {
+	res, err := http.Get(url)
 	if err != nil {
 		panic(err)
 	}
@@ -198,7 +239,7 @@ func get(url string) string {
 		panic(err)
 	}
 
-	return string(body)
+	return res.StatusCode, res.Header, string(body)
 }
 
 func newTestRouterServer(kvstore store.Store, log *zap.Logger) (*Router, *httptest.Server) {

router/router.go

@@ -55,10 +55,17 @@ func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	payload, err := json.Marshal(event)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
 	if event.Event == eventHTTP || event.Event == eventInvoke {
-		router.handleSyncEvent(event, w, r)
+		router.handleSyncEvent(event.Event, payload, w, r)
 	} else if r.Method == http.MethodPost && r.URL.Path == "/" {
-		router.handleAsyncEvent(event, w, r)
+		router.enqueueWork(subscriptions.TopicID(event.Event), payload)
+		w.WriteHeader(http.StatusAccepted)
 	}
 }
 
@@ -159,20 +166,15 @@ var (
 	errUnableToLookUpRegisteredFunction = errors.New("unable to look up registered function")
 )
 
-func (router *Router) handleSyncEvent(event *Event, w http.ResponseWriter, r *http.Request) {
-	payload, err := json.Marshal(event)
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
+func (router *Router) handleSyncEvent(name string, payload []byte, w http.ResponseWriter, r *http.Request) {
 	router.log.Debug("Event received.", zap.String("event", string(payload)))
 
 	var resp []byte
 	var functionID functions.FunctionID
-	if event.Event == eventInvoke {
+
+	if name == eventInvoke {
 		functionID = functions.FunctionID(r.Header.Get(headerFunctionID))
-	} else if event.Event == eventHTTP {
+	} else if name == eventHTTP {
 		endpointID := subscriptions.NewEndpointID(strings.ToUpper(r.Method), r.URL.EscapedPath())
 		backingFunction := router.targetCache.BackingFunction(endpointID)
 		if backingFunction == nil {
@@ -183,10 +185,9 @@ func (router *Router) handleSyncEvent(event *Event, w http.ResponseWriter, r *ht
 		functionID = *backingFunction
 	}
 
-	router.log.Debug("Function triggered.",
-		zap.String("functionId", string(functionID)), zap.String("event", string(payload)))
+	router.log.Debug("Function triggered.", zap.String("functionId", string(functionID)), zap.String("event", string(payload)))
 
-	resp, err = router.callFunction(functionID, payload)
+	resp, err := router.callFunction(functionID, payload)
 	if err != nil {
 		router.log.Warn("Function invocation failed.",
 			zap.String("functionId", string(functionID)), zap.String("event", string(payload)), zap.Error(err))
@@ -195,16 +196,8 @@ func (router *Router) handleSyncEvent(event *Event, w http.ResponseWriter, r *ht
 			http.Error(w, err.Error(), http.StatusNotFound)
 		} else {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
-		}
 
-		if _, ok := err.(*functions.ErrFunctionCallFailedProviderError); ok {
-			internal := NewEvent(internalFunctionProviderError, mimeJSON, struct {
-				FunctionID string `json:"functionId"`
-			}{string(functionID)})
-			payload, err = json.Marshal(internal)
-			if err == nil {
-				router.enqueueWork(subscriptions.TopicID(internal.Event), payload)
-			}
+			router.emitFunctionProviderErrorEvent(functionID, payload, err)
 		}
 
 		return
@@ -214,22 +207,39 @@ func (router *Router) handleSyncEvent(event *Event, w http.ResponseWriter, r *ht
 		zap.String("functionId", string(functionID)), zap.String("event", string(payload)),
 		zap.String("response", string(resp)))
 
+	if name == eventHTTP {
+		httpResponse := &HTTPResponse{StatusCode: http.StatusOK}
+		err = json.Unmarshal(resp, httpResponse)
+		if err == nil {
+			for key, value := range httpResponse.Headers {
+				w.Header().Set(key, value)
+			}
+
+			w.WriteHeader(httpResponse.StatusCode)
+
+			resp = []byte(httpResponse.Body)
+		}
+	}
+
 	_, err = w.Write(resp)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 }
 
-func (router *Router) handleAsyncEvent(instance *Event, w http.ResponseWriter, r *http.Request) {
-	payload, err := json.Marshal(instance)
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
+func (router *Router) enqueueWork(topic subscriptions.TopicID, payload []byte) {
+	router.log.Debug("Event received.", zap.String("event", string(payload)))
 
-	router.enqueueWork(subscriptions.TopicID(instance.Event), payload)
-	w.WriteHeader(http.StatusAccepted)
+	select {
+	case router.work <- event{
+		topic:   topic,
+		payload: payload,
+	}:
+	default:
+		// We could not submit any work, this is NOT good but we will sacrifice consistency for availability for now.
+		router.dropMetric.Inc()
+	}
 }
 
 // callFunction looks up a function and calls it.
@@ -325,17 +335,15 @@ func (router *Router) processEvent(e event) {
 	}
 }
 
-func (router *Router) enqueueWork(topic subscriptions.TopicID, payload []byte) {
-	router.log.Debug("Event received.", zap.String("event", string(payload)))
-
-	select {
-	case router.work <- event{
-		topic:   topic,
-		payload: payload,
-	}:
-	default:
-		// We could not submit any work, this is NOT good but we will sacrifice consistency for availability for now.
-		router.dropMetric.Inc()
+func (router *Router) emitFunctionProviderErrorEvent(functionID functions.FunctionID, payload []byte, err error) {
+	if _, ok := err.(*functions.ErrFunctionCallFailedProviderError); ok {
+		internal := NewEvent(internalFunctionProviderError, mimeJSON, struct {
+			FunctionID string `json:"functionId"`
+		}{string(functionID)})
+		payload, err = json.Marshal(internal)
+		if err == nil {
+			router.enqueueWork(subscriptions.TopicID(internal.Event), payload)
+		}
 	}
 }