feat(authorizer): added authorization

authorizer.js

@@ -0,0 +1,46 @@
+const aws = require('aws-sdk');
+
+const dynamoDB = new aws.DynamoDB.DocumentClient();
+
+function generatePolicy(principalId, effect, resource) {
+  const policy = {
+    principalId,
+    policyDocument: {
+      Version: '2012-10-17',
+      Statement: [{
+        Action: 'execute-api:Invoke',
+        Effect: effect,
+        Resource: resource
+      }]
+    }
+  };
+  return policy;
+}
+
+async function validateToken(userToken) {
+  const token = userToken.split('Bearer ')[1];
+  const params = {
+    TableName: process.env.dynamodb_table_name,
+    IndexName: process.env.dynamodb_index_name,
+    KeyConditionExpression: '#token = :token',
+    ExpressionAttributeNames: {
+      '#token': 'bearer_token'
+    },
+    ExpressionAttributeValues: {
+      ':token': token
+    }
+  };
+  const data = await dynamoDB.query(params).promise();
+  return data.Items[0];
+}
+
+exports.handler = async (event) => { // eslint-disable-line no-unused-vars
+  const userToken = event.authorizationToken;
+  const arn = event.methodArn;
+  const user = await validateToken(userToken);
+  if (user) {
+    return generatePolicy('user', 'Allow', arn);
+  } else { // eslint-disable-line no-else-return
+    return generatePolicy('user', 'Deny', arn);
+  }
+};