madhu-sv/tweets

Tweets API as AWS Lambda with API Gateway and DynamoDB

tweets

Tweets API as AWS Lambda with API Gateway and DynamoDB

Architecture

Tweets is driven by AWS API Gateway and AWS Lambdas. Backed by Dynamo DB as the backend for storing the Tweet data model.

AWS Lambda Route

I decided to go the AWs Lambda route purely for cost/time reasons. Other options include * ECS Fargate to replace all Lambdas except the Lambda Authorizer backed by NLB inside a private subnet. * Spring Cloud Native * Elastic bean with RDS

Security

All the lambdas are running inside VPC with each having it's won security groups. No internet access to any of them. All resources including Privatelinks, VPC Endpoints, Lambdas and Secrets (with KMS) are protected using IAM and Security groups and have limited access using the least privilege principle.

Tweet Data Model

Tweet data model is inspired from Twitter The actual json looks like

{
    "Tweet": {
        "id": "123460",
        "user": {
            "description": "user3",
            "followersCount": 1234,
            "userId": "user3",
            "userName": "user3",
            "verified": false
        },
        "entities": {},
        "favorite": true,
        "retweeted": false,
        "text": "New tweet alert for user3"
    }
}

where user is another Java POJO used as a DynamoDBDocument It looks like

@DynamoDBDocument
public class User {
	private String description;
	private Integer followersCount;
	private String userId;
	private String userName;
	private boolean verified;
    //Omitted for brevity...
}

and entities the same

@DynamoDBDocument
public class Entities {
	private List<String> hashTags;
	private List<String> URLs;
    //Omitted for brevity...
}

I have used DynamoDBMapper to avoid manually parsing JSON to POJO to perform the CRUD operations

Instructions for build This is a multi module maven project and all the AWS Lambdas are built using the maven shade plugin

build command

mvn clean package shade:shade

Testing Endpoints

Login

Curl command to test the login

curl -X POST -H "Content-Type: application/json"  -d '{"Id": "123459","user": {"userName": "user4","password":"<password_here>"}' \
https://0tg9vck032.execute-api.eu-west-2.amazonaws.com/test/login`

Example Respone

`{
  "token": eyJhbGciOiJIUzI1NiJ9.eyJuYW1lIjoidXNlcjMiLCJpc3MiOiJtYWRodXN1ZGhhbiIsImF1ZCI6InRlc3QgYXVkaWVuY2UiLCJleHAiOjE2NDI0MTM5NTR9.mEMnKaF2GUkA4zGhG7dVwACk_Tvc3HSDTjJJPxQoAKE"
 }

Create

Curl command to test the endpoint

curl -X PUT -H "Content-Type: application/json"  -H "Authorization: Bearer <token goes here>" -d '{"Id": "<new_id_here>","user": {"userName": "user4","verified": false,"userId": "user4","description": "user4","followersCount": 123},
    "text": "New tweet alert for user4", \
    "favorite": true, \
    "retweeted": false, \
    "entities": { \
        "hashtags": [ \
            "#tweettweet" \
        ], \
        "URLs": [ \
            "https://exampleurl.madhu" \
        ] \
    } \
}' \
https://0tg9vck032.execute-api.eu-west-2.amazonaws.com/test/tweets/create

Example Response

{
    "message": "New tweet created"
}

Get Tweets

GetAllTweets Curl command to test the endpoint

curl -X GET -H "Content-Type: application/json"  -H "Authorization: Bearer <token goes here>"  https://0tg9vck032.execute-api.eu-west-2.amazonaws.com/test/tweets

Example Response

{
    "tweetCount": 5,
    "tweets": "[{\"id\":\"123456\",\"user\":{\"description\":\"user1\",\"followersCount\":123,\"userId\":\"user1\",\"userName\":\"user1\",\"verified\":false},\"favorite\":false,\"retweeted\":false,\"text\":\"My first tweet!!!\"},{\"id\":\"123458\",\"user\":{\"description\":\"user1\",\"followersCount\":123,\"userId\":\"user1\",\"userName\":\"user1\",\"verified\":false},\"entities\":{},\"favorite\":true,\"retweeted\":true,\"text\":\"New tweet alert again\"},{\"id\":\"123459\",\"user\":{\"description\":\"user4\",\"followersCount\":123,\"userId\":\"user4\",\"userName\":\"user4\",\"verified\":false},\"entities\":{},\"favorite\":true,\"retweeted\":false,\"text\":\"New tweet alert for user4\"},{\"id\":\"123457\",\"user\":{\"description\":\"user1\",\"followersCount\":123,\"userId\":\"user1\",\"userName\":\"user1\",\"verified\":false},\"entities\":{},\"favorite\":false,\"retweeted\":false,\"text\":\"New tweet alert\"},{\"id\":\"123460\",\"user\":{\"description\":\"user3\",\"followersCount\":1234,\"userId\":\"user3\",\"userName\":\"user3\",\"verified\":false},\"entities\":{},\"favorite\":true,\"retweeted\":false,\"text\":\"New tweet alert for user3\"}]"
}

GetTweetsById Curl command to test the endpoint

curl -X GET -H "Content-Type: application/json"  -H "Authorization: Bearer <token goes here>"  https://0tg9vck032.execute-api.eu-west-2.amazonaws.com/test/tweets/{id}

Example Response

{
    "Tweet": {
        "id": "123460",
        "user": {
            "description": "user3",
            "followersCount": 1234,
            "userId": "user3",
            "userName": "user3",
            "verified": false
        },
        "entities": {},
        "favorite": true,
        "retweeted": false,
        "text": "New tweet alert for user3"
    }
}