Become an AWS pro by getting hands-on with API Gateway. Developed by AWS Solution Certified Architects, you’ll build secure apps, integrate services, and create a chat app. No setup, no cleanup, no hassle.

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API Gateway is an important component of the AWS serverless stack and has great potential to enable low latency, low-cost, and secure applications. This course takes you through all aspects of the AWS API Gateway and contains ready-to-use code snippets to implement different patterns of serverless API development in AWS. 

You’ll learn core concepts and get hands-on experience with core API Gateway capabilities. You’ll also dive deep into data mapping and WebSocket APIs and build a fully functional multi-user chat application with WebSocket API. You’ll learn about various services that can integrate with the API Gateway. Throughout the course, you’ll use IaC to provision resources, coupled with an introduction to CloudFormation. You’ll conclude the course by building a fully functional chat application with a bot that listens to the conversation and sends random jokes when asked.

Through detailed lessons covering theoretical and practical knowledge, this course helps you master the AWS API Gateway service.

AWS API Gateway: The Unsung Warrior

# API gateway - "hello world"
It’s fair to ask why we need the API Gateway when we can develop the full API using Lambda function alone. It’s because API Gateway offers us a lot more than this. It has several features that help us scale the API beyond this.

The power and versatility of the Lambda functions are impressive. But, in the process, many of us miss out on the features available in the other supporting services. If we master them, our applications can scale significantly, improving cost, latency, and security.

Let’s use an API Gateway to extend the Hello World API from the previous lesson.

The code below extends the IaC we developed in the previous lesson to invoke the Lambda function using an API Gateway.

Again, don’t worry if you don’t fully understand the syntax of this code. For now, click and see the deployment.


/**
 * This code is deployed as the Lambda function in AWS. 
 * It just returns the simple string Hello World.
 */

exports.handler = async(event, context) => {
  return "Hello World";
};


#!/bin/sh -v

# -----------------------------------------------------------------
# Configure the AWS CLI to let it communicate with your account
# -----------------------------------------------------------------
aws configure set aws_access_key_id $aws_access_key_id
aws configure set aws_secret_access_key $aws_secret_access_key
aws configure set region us-east-1

# -----------------------------------------------------------------
# Delete any old deployments
# -----------------------------------------------------------------
# 1. Trigger CloudFormation stack delete
# 2. Wait for the stack to be deleted 
aws cloudformation delete-stack --stack-name  EducativeCourseApiGateway
aws cloudformation wait stack-delete-complete --stack-name EducativeCourseApiGateway


# -----------------------------------------------------------------
# Deploying a Lambda Function requires two steps.
# -----------------------------------------------------------------
# 1. Create a deployment ZIP file and upload it to S3
# 2. Deploy the CloudFormation template that picks this ZIP file and makes a Lambda function
#
# The below code will do both

# -----------------------------------------------------------------
# Cleanup anything that is left over from the last deployment.
# -----------------------------------------------------------------
rm -f *.zip 

# -----------------------------------------------------------------
# Create a unique S3 Bucket. The name of S3 bucket is derived from the access key. So it has to be unique
# -----------------------------------------------------------------
bucket=`echo $aws_access_key_id | tr '[:upper:]' '[:lower:]'`
aws s3 mb s3://educative.${bucket} --region us-east-1

# -----------------------------------------------------------------
# It is important that this zip file has a new name everytime we deploy. Else, the new code is not picked.
# We start by creating a random string. This is an important part of CloudFormation deployments.
# -----------------------------------------------------------------
RAND=$(dd if=/dev/random bs=8 count=1 2>/dev/null | od -An -tx1 | tr -d ' \t\n')

# -----------------------------------------------------------------
# Build the zip file that we want to deploy. At this point, we include the index.js in our 
# -----------------------------------------------------------------
zip -r ${RAND}.zip index.js

# -----------------------------------------------------------------
# Upload the lambda zip file to the S3 bucket. 
# -----------------------------------------------------------------
aws s3 cp ${RAND}.zip s3://educative.${bucket}

# -----------------------------------------------------------------
# With everything ready, we initiate the CloudFormation deployment.
# -----------------------------------------------------------------
aws cloudformation deploy \
    --template-file template.yml \
    --stack-name EducativeCourseApiGateway \
    --capabilities CAPABILITY_NAMED_IAM \
    --parameter-overrides DeployId="$RAND" SourceCodeBucket="educative.${bucket}" \
    --region us-east-1

# -----------------------------------------------------------------
# Get the API ID of the Rest API we just created.
# -----------------------------------------------------------------
apiId=`aws cloudformation list-stack-resources --stack-name EducativeCourseApiGateway | jq -r ".StackResourceSummaries[3].PhysicalResourceId"`
echo "API ID: $apiId"

# -----------------------------------------------------------------
# This is the URL for the API we just created
# -----------------------------------------------------------------
url="https://${apiId}.execute-api.us-east-1.amazonaws.com/v1/hello"
echo $url

# -----------------------------------------------------------------
# Invoke the URL to test the response
# -----------------------------------------------------------------
curl $url


AWSTemplateFormatVersion: "2010-09-09"
Parameters:
  DeployId:
    Type: String
    Default: afsf34sfdg
  SourceCodeBucket:
    Type: String
    Default: afsf34sfdg
Resources:
  HelloWorldLambda:
    Type: AWS::Lambda::Function
    Properties:
      Handler: index.handler
      Role: !GetAtt LambdaExecutionRole.Arn
      FunctionName: EducativeHelloWorld
      Code:
        S3Bucket:
          Ref: SourceCodeBucket
        S3Key: !Sub "${DeployId}.zip"
      Runtime: nodejs16.x
      Timeout: 3
      MemorySize: 128
  RestAPI:
    Type: AWS::ApiGateway::RestApi
    Properties:
      EndpointConfiguration:
        Types:
          - REGIONAL
      Body:
        openapi: "3.0.1"
        info:
          title: "EducativeRestAPI"
          description: "Rest API for Educative API Gateway Course"
          version: "2022-06-06T10:08:49Z"
        paths:
          /hello:
            x-amazon-apigateway-any-method:
              responses:
                "200":
                  description: "200 response"
                  content:
                    application/json:
                      schema:
                        $ref: "#/components/schemas/Empty"
              x-amazon-apigateway-integration:
                httpMethod: "POST"
                uri: "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/arn:aws:lambda:${AWS::Region}:${AWS::AccountId}:function:EducativeHelloWorld/invocations"
                responses:
                  default:
                    statusCode: "200"
                passthroughBehavior: "when_no_match"
                contentHandling: "CONVERT_TO_TEXT"
                type: "aws"
                credentials: "arn:aws:iam::${AWS::AccountId}:role/EducativeLambdaRole"
        components:
          schemas:
            Empty:
              title: "Empty Schema"
              type: "object"
      Name: EducativeRestAPI
      Description: "Rest API for Educative API Gateway Course"
      Mode: overwrite
  LambdaExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: EducativeLambdaRole
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
                - apigateway.amazonaws.com
            Action:
              - sts:AssumeRole
      Path: "/"
      ManagedPolicyArns:
        - !Join 
            - ''
            - - 'arn:aws:iam::'
              - !Ref 'AWS::AccountId'
              - ':policy/APIGatewayCustomPolicy'
  APIDeployment:
    Type: AWS::ApiGateway::Deployment
    Properties:
      RestApiId:
        Ref: RestAPI
      StageName: v1


Introduction to API Gateway

API Gateway: High Level View

Getting Started with AWS API Gateway

API Gateway: Basic Configurations

Data Mapping Deep Dive

Leveraging AWS API Gateway for Public API Integration

Websocket Deep Dive

AWS Service Integration Deep Dive

Integrating AWS Services with API Gateway

Appendix

API Gateway Evaluation

Chat Application with Jokes Bot

Building a Chat Application Using Lambda Function and API Gateway

What's API Gateway?

API gateway - “hello world”