Módulo 3 | Implementando a solicitação via IAM, AWS Lambda e DynamoDB…

… #01

js/lambda.js

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+const randomBytes = require("crypto").randomBytes;
+const AWS = require("aws-sdk");
+const ddb = new AWS.DynamoDB.DocumentClient();
+
+const fleet = [
+  {
+    Name: "Angel",
+    Color: "White",
+    Gender: "Female",
+  },
+  {
+    Name: "Gil",
+    Color: "White",
+    Gender: "Male",
+  },
+  {
+    Name: "Rocinante",
+    Color: "Yellow",
+    Gender: "Female",
+  },
+];
+
+exports.handler = (event, context, callback) => {
+  if (!event.requestContext.authorizer) {
+    errorResponse(
+      "Authorization not configured",
+      context.awsRequestId,
+      callback
+    );
+    return;
+  }
+
+  const rideId = toUrlString(randomBytes(16));
+  console.log("Received event (", rideId, "): ", event);
+
+  // Because we're using a Cognito User Pools authorizer, all of the claims
+  // included in the authentication token are provided in the request context.
+  // This includes the username as well as other attributes.
+  const username = event.requestContext.authorizer.claims["cognito:username"];
+
+  // The body field of the event in a proxy integration is a raw string.
+  // In order to extract meaningful values, we need to first parse this string
+  // into an object. A more robust implementation might inspect the Content-Type
+  // header first and use a different parsing strategy based on that value.
+  const requestBody = JSON.parse(event.body);
+
+  const pickupLocation = requestBody.PickupLocation;
+
+  const unicorn = findUnicorn(pickupLocation);
+
+  recordRide(rideId, username, unicorn)
+    .then(() => {
+      // You can use the callback function to provide a return value from your Node.js
+      // Lambda functions. The first parameter is used for failed invocations. The
+      // second parameter specifies the result data of the invocation.
+
+      // Because this Lambda function is called by an API Gateway proxy integration
+      // the result object must use the following structure.
+      callback(null, {
+        statusCode: 201,
+        body: JSON.stringify({
+          RideId: rideId,
+          Unicorn: unicorn,
+          Eta: "30 seconds",
+          Rider: username,
+        }),
+        headers: {
+          "Access-Control-Allow-Origin": "*",
+        },
+      });
+    })
+    .catch((err) => {
+      console.error(err);
+
+      // If there is an error during processing, catch it and return
+      // from the Lambda function successfully. Specify a 500 HTTP status
+      // code and provide an error message in the body. This will provide a
+      // more meaningful error response to the end client.
+      errorResponse(err.message, context.awsRequestId, callback);
+    });
+};
+
+// This is where you would implement logic to find the optimal unicorn for
+// this ride (possibly invoking another Lambda function as a microservice.)
+// For simplicity, we'll just pick a unicorn at random.
+function findUnicorn(pickupLocation) {
+  console.log(
+    "Finding unicorn for ",
+    pickupLocation.Latitude,
+    ", ",
+    pickupLocation.Longitude
+  );
+  return fleet[Math.floor(Math.random() * fleet.length)];
+}
+
+function recordRide(rideId, username, unicorn) {
+  return ddb
+    .put({
+      TableName: "Rides",
+      Item: {
+        RideId: rideId,
+        User: username,
+        Unicorn: unicorn,
+        RequestTime: new Date().toISOString(),
+      },
+    })
+    .promise();
+}
+
+function toUrlString(buffer) {
+  return buffer
+    .toString("base64")
+    .replace(/\+/g, "-")
+    .replace(/\//g, "_")
+    .replace(/=/g, "");
+}
+
+function errorResponse(errorMessage, awsRequestId, callback) {
+  callback(null, {
+    statusCode: 500,
+    body: JSON.stringify({
+      Error: errorMessage,
+      Reference: awsRequestId,
+    }),
+    headers: {
+      "Access-Control-Allow-Origin": "*",
+    },
+  });
+}

js/validacao_lambda.json

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+{
+  "path": "/ride",
+  "httpMethod": "POST",
+  "headers": {
+    "Accept": "*/*",
+    "Authorization": "eyJraWQiOiJLTzRVMWZs",
+    "content-type": "application/json; charset=UTF-8"
+  },
+  "queryStringParameters": null,
+  "pathParameters": null,
+  "requestContext": {
+    "authorizer": {
+      "claims": {
+        "cognito:username": "the_username"
+      }
+    }
+  },
+  "body": "{\"PickupLocation\":{\"Latitude\":47.6174755835663,\"Longitude\":-122.28837066650185}}"
+}