Use the Init and Exit error signals provided by the Extension API (#145)

* Use Init and Exit error codes (incl. demo code)

* Remove APM example

* Increase the range of valid StatusCodes

Co-authored-by: Felix Barnsteiner <felixbarny@users.noreply.github.com>

* Remove demonstration code

* Quick fix : make changes compatible with logger

Co-authored-by: Felix Barnsteiner <felixbarny@users.noreply.github.com>

Author: jlvoiseux

apm-lambda-extension/extension/client.go

@@ -160,7 +160,7 @@ func (e *Client) InitError(ctx context.Context, errorType string) (*StatusRespon
 	}
 	defer httpRes.Body.Close()
 
-	if httpRes.StatusCode != 200 {
+	if httpRes.StatusCode > 299 {
 		return nil, fmt.Errorf("initialization error request failed with status %s", httpRes.Status)
 	}
 	res := StatusResponse{}
@@ -187,7 +187,7 @@ func (e *Client) ExitError(ctx context.Context, errorType string) (*StatusRespon
 	}
 	defer httpRes.Body.Close()
 
-	if httpRes.StatusCode != 200 {
+	if httpRes.StatusCode > 299 {
 		return nil, fmt.Errorf("exit error request failed with status %s", httpRes.Status)
 	}
 	res := StatusResponse{}

apm-lambda-extension/main.go

@@ -39,6 +39,7 @@ var (
 /* --- elastic vars  --- */
 
 func main() {
+
 	ctx, cancel := context.WithCancel(context.Background())
 
 	// Trigger ctx.Done() in all relevant goroutines when main ends
@@ -59,7 +60,14 @@ func main() {
 	// register extension with AWS Extension API
 	res, err := extensionClient.Register(ctx, extensionName)
 	if err != nil {
-		panic(err)
+		status, errRuntime := extensionClient.InitError(ctx, err.Error())
+		if errRuntime != nil {
+			panic(errRuntime)
+		}
+		extension.Log.Errorf("Error: %s", err)
+		extension.Log.Infof("Init error signal sent to runtime : %s", status)
+		extension.Log.Infof("Exiting")
+		return
 	}
 	extension.Log.Debugf("Register response: %v", extension.PrettyPrint(res))
 
@@ -105,7 +113,13 @@ func main() {
 			extension.Log.Infof("Waiting for next event...")
 			event, err := extensionClient.NextEvent(ctx)
 			if err != nil {
-				extension.Log.Errorf("Error: %v\n. Exiting.", err)
+				status, err := extensionClient.ExitError(ctx, err.Error())
+				if err != nil {
+					panic(err)
+				}
+				extension.Log.Errorf("Error: %s", err)
+				extension.Log.Infof("Exit signal sent to runtime : %s", status)
+				extension.Log.Infof("Exiting")
 				return
 			}
 			extension.Log.Debug("Received event.")