standardize errors returned by both Events and Config API (#359)

Always return JSON object with `errors` field.

.gitignore

@@ -1,3 +1,4 @@
+.idea
 /event-gateway
 vendor
 *.swp

functions/httpapi.go

@@ -34,7 +34,7 @@ func (h HTTPAPI) getFunction(w http.ResponseWriter, r *http.Request, params http
 			w.WriteHeader(http.StatusInternalServerError)
 		}
 
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 	} else {
 		encoder.Encode(fn)
 	}
@@ -47,7 +47,7 @@ func (h HTTPAPI) getFunctions(w http.ResponseWriter, r *http.Request, params htt
 	fns, err := h.Functions.GetAllFunctions()
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 	} else {
 		encoder.Encode(&functions{fns})
 	}
@@ -80,7 +80,7 @@ func (h HTTPAPI) registerFunction(w http.ResponseWriter, r *http.Request, params
 			w.WriteHeader(http.StatusInternalServerError)
 		}
 
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 		return
 	}
 
@@ -111,7 +111,7 @@ func (h HTTPAPI) updateFunction(w http.ResponseWriter, r *http.Request, params h
 			w.WriteHeader(http.StatusInternalServerError)
 		}
 
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 		return
 	}
 
@@ -130,7 +130,7 @@ func (h HTTPAPI) deleteFunction(w http.ResponseWriter, r *http.Request, params h
 			w.WriteHeader(http.StatusInternalServerError)
 		}
 
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 	} else {
 		w.WriteHeader(http.StatusNoContent)
 	}

internal/httpapi/error.go

@@ -2,9 +2,13 @@ package httpapi
 
 import "fmt"
 
+type Response struct {
+	Errors []Error `json:"errors"`
+}
+
 // Error represents generic HTTP error returned by Configuration API.
 type Error struct {
-	Error string `json:"error"`
+	Message string `json:"message"`
 }
 
 // ErrMalformedJSON occurring when it's impossible to decode JSON payload.

router/router.go

@@ -3,7 +3,6 @@ package router
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"io/ioutil"
 	"net/http"
 	"regexp"
@@ -17,6 +16,7 @@ import (
 	eventpkg "github.com/serverless/event-gateway/event"
 	"github.com/serverless/event-gateway/functions"
 	"github.com/serverless/event-gateway/plugin"
+	"github.com/serverless/event-gateway/internal/httpapi"
 )
 
 // Router calls a target function when an endpoint is hit, and handles pubsub message delivery.
@@ -47,9 +47,12 @@ func New(workersNumber uint, backlogLength uint, targetCache Targeter, plugins *
 }
 
 func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	encoder := json.NewEncoder(w)
 	// if we're draining requests, spit back a 503
 	if router.isDraining() {
-		http.Error(w, http.StatusText(http.StatusServiceUnavailable), http.StatusServiceUnavailable)
+		w.WriteHeader(http.StatusServiceUnavailable)
+		w.Header().Set("content-type", "application/json")
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: http.StatusText(http.StatusServiceUnavailable) }}})
 		return
 	}
 
@@ -60,7 +63,9 @@ func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		event, _, err := router.eventFromRequest(r)
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusBadRequest)
+			w.WriteHeader(http.StatusBadRequest)
+			w.Header().Set("content-type", "application/json")
+			encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 			return
 		}
 
@@ -69,13 +74,16 @@ func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		cors.AllowAll().ServeHTTP(w, r, func(w http.ResponseWriter, r *http.Request) {
 			if r.Method != http.MethodPost {
 				w.WriteHeader(http.StatusBadRequest)
-				fmt.Fprintln(w, "custom event can be emitted only with POST method")
+				w.Header().Set("content-type", "application/json")
+				encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: "custom event can be emitted only with POST method" }}})
 				return
 			}
 
 			event, path, err := router.eventFromRequest(r)
 			if err != nil {
-				http.Error(w, err.Error(), http.StatusBadRequest)
+				w.WriteHeader(http.StatusBadRequest)
+				w.Header().Set("content-type", "application/json")
+				encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 				return
 			}
 
@@ -242,6 +250,7 @@ func (router *Router) eventFromRequest(r *http.Request) (*eventpkg.Event, string
 	return event, path, nil
 }
 func (router *Router) handleHTTPEvent(event *eventpkg.Event, w http.ResponseWriter, r *http.Request) {
+	encoder := json.NewEncoder(w)
 	reqMethod := r.Method
 
 	// check if CORS pre-flight request
@@ -253,7 +262,9 @@ func (router *Router) handleHTTPEvent(event *eventpkg.Event, w http.ResponseWrit
 	)
 	if backingFunction == nil {
 		router.log.Debug("Function not found for HTTP event.", zap.Object("event", event))
-		http.Error(w, "resource not found", http.StatusNotFound)
+		w.WriteHeader(http.StatusNotFound)
+		w.Header().Set("content-type", "application/json")
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: "resource not found" }}})
 		return
 	}
 
@@ -263,15 +274,19 @@ func (router *Router) handleHTTPEvent(event *eventpkg.Event, w http.ResponseWrit
 		event.Data = httpdata
 		resp, err := router.callFunction(*backingFunction, *event)
 		if err != nil {
-			http.Error(w, "function call failed", http.StatusInternalServerError)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Header().Set("content-type", "application/json")
+			encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: "function call failed" }}})
 			return
 		}
 
 		httpResponse := &HTTPResponse{StatusCode: http.StatusOK}
 		err = json.Unmarshal(resp, httpResponse)
 		if err != nil {
 			router.log.Info("HTTP response object malformed.", zap.String("response", string(resp)))
-			http.Error(w, "HTTP response object malformed", http.StatusInternalServerError)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Header().Set("content-type", "application/json")
+			encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: "HTTP response object malformed" }}})
 			return
 		}
 
@@ -283,7 +298,9 @@ func (router *Router) handleHTTPEvent(event *eventpkg.Event, w http.ResponseWrit
 
 		_, err = w.Write(resp)
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Header().Set("content-type", "application/json")
+			encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 			return
 		}
 
@@ -306,23 +323,30 @@ func (router *Router) handleHTTPEvent(event *eventpkg.Event, w http.ResponseWrit
 }
 
 func (router *Router) handleInvokeEvent(path string, event *eventpkg.Event, w http.ResponseWriter, r *http.Request) {
+	encoder := json.NewEncoder(w)
 	routerEventsSyncReceived.Inc()
 
 	functionID := functions.FunctionID(r.Header.Get(headerFunctionID))
 	if !router.targetCache.InvokableFunction(path, functionID) {
-		http.Error(w, "function or subscription not found", http.StatusNotFound)
+		w.WriteHeader(http.StatusNotFound)
+		w.Header().Set("content-type", "application/json")
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: "function or subscription not found" }}})
 		return
 	}
 
 	resp, err := router.callFunction(functionID, *event)
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Header().Set("content-type", "application/json")
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 		return
 	}
 
 	_, err = w.Write(resp)
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Header().Set("content-type", "application/json")
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 		return
 	}
 

subscriptions/httpapi.go

@@ -48,7 +48,7 @@ func (h HTTPAPI) createSubscription(w http.ResponseWriter, r *http.Request, para
 			w.WriteHeader(http.StatusInternalServerError)
 		}
 
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 		return
 	}
 
@@ -70,7 +70,7 @@ func (h HTTPAPI) deleteSubscription(w http.ResponseWriter, r *http.Request, para
 		} else {
 			w.WriteHeader(http.StatusInternalServerError)
 		}
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 	} else {
 		w.WriteHeader(http.StatusNoContent)
 	}
@@ -83,7 +83,7 @@ func (h HTTPAPI) getSubscriptions(w http.ResponseWriter, r *http.Request, params
 	subs, err := h.Subscriptions.GetAllSubscriptions()
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
-		encoder.Encode(&httpapi.Error{Error: err.Error()})
+		encoder.Encode(&httpapi.Response{Errors: []httpapi.Error{{ Message: err.Error() }}})
 	} else {
 		encoder.Encode(&subscriptions{subs})
 	}