controller: add content type option to send in the headers when invoking a function

Signed-off-by: Carlos Panato <[email protected]>

Author: cpanato

README.md

@@ -73,6 +73,16 @@ Set the following in `ControllerConfig`:
 	}
 ```
 
+If you need to use the `Content-Type` header to validate or to check when it invoke the function you can set the `Content-Type`
+in `ControllerConfig`:
+
+```go
+	config := &types.ControllerConfig{
+        ...
+		ContentType: "application/json",
+	}
+```
+
 View the code: [cmd/tester/main.go](cmd/tester/main.go)
 
 ## License

types/controller.go

@@ -38,6 +38,10 @@ type ControllerConfig struct {
 
 	// PrintSync indicates whether the sync should be logged.
 	PrintSync bool
+
+	// ContentType defines which content type will be set in the header to inkoke the function. i.e "application/json".
+	// Optional, if not set the Content-Type header will not be set.
+	ContentType string
 }
 
 // Controller is used to invoke functions on a per-topic basis and to subscribe to responses returned by said functions.
@@ -79,6 +83,7 @@ func NewController(credentials *auth.BasicAuthCredentials, config *ControllerCon
 
 	invoker := NewInvoker(gatewayFunctionPath,
 		MakeClient(config.UpstreamTimeout),
+		config.ContentType,
 		config.PrintResponse)
 
 	subs := []ResponseSubscriber{}

types/invoker.go

@@ -21,6 +21,7 @@ type Invoker struct {
 	PrintResponse bool
 	Client        *http.Client
 	GatewayURL    string
+	ContentType   string
 	Responses     chan InvokerResponse
 }
 
@@ -37,11 +38,12 @@ type InvokerResponse struct {
 }
 
 // NewInvoker constructs an Invoker instance
-func NewInvoker(gatewayURL string, client *http.Client, printResponse bool) *Invoker {
+func NewInvoker(gatewayURL string, client *http.Client, contentType string, printResponse bool) *Invoker {
 	return &Invoker{
 		PrintResponse: printResponse,
 		Client:        client,
 		GatewayURL:    gatewayURL,
+		ContentType:   contentType,
 		Responses:     make(chan InvokerResponse),
 	}
 }
@@ -67,7 +69,7 @@ func (i *Invoker) InvokeWithContext(ctx context.Context, topicMap *TopicMap, top
 		gwURL := fmt.Sprintf("%s/%s", i.GatewayURL, matchedFunction)
 		reader := bytes.NewReader(*message)
 
-		body, statusCode, header, doErr := invokefunction(ctx, i.Client, gwURL, reader)
+		body, statusCode, header, doErr := invokefunction(ctx, i.Client, gwURL, i.ContentType, reader)
 
 		if doErr != nil {
 			i.Responses <- InvokerResponse{
@@ -88,7 +90,7 @@ func (i *Invoker) InvokeWithContext(ctx context.Context, topicMap *TopicMap, top
 	}
 }
 
-func invokefunction(ctx context.Context, c *http.Client, gwURL string, reader io.Reader) (*[]byte, int, *http.Header, error) {
+func invokefunction(ctx context.Context, c *http.Client, gwURL, contentType string, reader io.Reader) (*[]byte, int, *http.Header, error) {
 
 	httpReq, err := http.NewRequest(http.MethodPost, gwURL, reader)
 	if err != nil {
@@ -100,6 +102,10 @@ func invokefunction(ctx context.Context, c *http.Client, gwURL string, reader io
 		defer httpReq.Body.Close()
 	}
 
+	if contentType != "" {
+		httpReq.Header.Set("Content-Type", contentType)
+	}
+
 	var body *[]byte
 
 	res, doErr := c.Do(httpReq)