API Gateway Support (#4)

* Added commented out support for API Gateway to Serverless config
* Added a normalize response helper to support API Gateway
* Tweaked API GW support for POST instead of GET
Will now return the "Event type not supported" error if the httpMethod is a GET request, as body on GET is not standard practice.

serverless.yml

@@ -20,6 +20,9 @@ provider:
   timeout: 30
   tracing:
     lambda: true
+  # See the API Gateway event below for additional details on api keys
+  # apiKeys:
+  #   - key1
 
 functions:
   captureScreenshot:
@@ -51,12 +54,19 @@ functions:
       IS_MOBILE: "false"
       IS_LANDSCAPE: "false"
     events:
+      # SNS Event
       - sns:
           arn: !Ref chromdaTopic
           topicName: ${self:custom.snsTopic}
+      # API Gateway Events
+      # - http:
+      #     path: capture
+      #     method: post
+      # Uncomment the provider api key section above as well as the line
+      # below to enable private endpoint support
+      #     private: true
       # TODO: add SQS event
       # TODO: add Scheduled event
-      # TODO: add API Gateway event
 
 layers:
   chromda:

src/captureScreenshot.js

@@ -4,6 +4,7 @@ const { URL } = require("url");
 const chromeLambda = require("chrome-aws-lambda");
 const MrPuppetshot = require("mrpuppetshot");
 const normalizeEvent = require("./helpers/normalizeEvent");
+const normalizeResponse = require("./helpers/normalizeResponse");
 const S3Bucket = require("./helpers/s3bucket");
 
 // Defaults
@@ -131,5 +132,5 @@ exports.handler = async (event, callback) => {
 
   const response = await S3Bucket.upload(buffer, imageType, options.s3key);
 
-  return response;
+  return normalizeResponse(event, response);
 };

src/helpers/normalizeEvent.js

@@ -18,7 +18,7 @@ const normalizedEvent = event => {
       );
     }
     return JSON.parse(event.Records[0].body);
-  } else if ("httpMethod" in event) {
+  } else if ("httpMethod" in event && event.httpMethod === "POST") {
     return JSON.parse(event.body);
   } else if ("time" in event) {
     return event.detail;

src/helpers/normalizeResponse.js

@@ -0,0 +1,26 @@
+/**
+ * @typedef {import('aws-lambda').APIGatewayEvent} APIGatewayEvent
+ * @typedef {import('aws-lambda').ScheduledEvent} ScheduledEvent
+ * @typedef {import('aws-lambda').SNSEvent} SNSEvent
+ * @typedef {import('aws-lambda').SQSEvent} SQSEvent
+ */
+
+/**
+ * @param {APIGatewayEvent|ScheduledEvent|SNSEvent|SQSEvent} event
+ * @param response
+ */
+
+const normalizedResponse = (event, response) => {
+  if ("httpMethod" in event) {
+    return {
+      "statusCode": 200,
+      "body": JSON.stringify(response),
+      "isBase64Encoded": false
+    };
+  }
+  else {
+    return response;
+  }
+};
+
+module.exports = normalizedResponse;