Simple Chatting API Coding By Using Serverless Stack

It is a slack clone application made using aws serverless stack.
This repository contains only the backend technology.
The Authentication part is not implemented.

Stack

• Python3
• Serverless Framework
• AWS Lambda, AWS ApiGateway(websocket, httpapi)
• AWS Cognito User Pool
• AWS DynamoDB

Prerequisites

1. Need to create an aws account
2. Install Serverless Framework

   npm install -g serverless

3. Install AWS Cli and Configure your CLI user
   • Install AWS CLI
   • Configure the AWS CLI
4. Setting AWS Cognito User Pool
   • in this application case we set Post confirmation Lambda trigger
   • this lambda code is in Here
   • you need to manually set the content for this code

Deploy

you can simply deploy enter this command

serverless deploy

The expected result should be similar to:

Running "serverless" from node_modules

Deploying slack-backend to stage dev (ap-northeast-2)

✔ Service deployed to stack slack-backend (125s)

endpoints:
  POST - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/user
  POST - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/workspace
  DELETE - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/workspace/{workspace_id}
  GET - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/workspace/{workspace_id}
  GET - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/workspaces/{user_email}
  PATCH - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/workspace
  PATCH - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/workspace/out
  POST - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/channel
  DELETE - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/channel/{workspace_id}/{channel_id}
  GET - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/channel/{workspace_id}/{channel_id}
  GET - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/channels/{workspace_id}/{user_email}
  PATCH - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/channel
  PATCH - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/channel/out
  GET - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/messages/{workspace_id}/{channel_id}
  GET - https://xxxxxxx.execute-api.ap-northeast-2.amazonaws.com/dm/{sender}/{receiver}
  wss://xxxxxx.execute-api.ap-northeast-2.amazonaws.com/{stage}
functions:
  addUser: slack-backend-addUser (138 kB)
  addWorkspace: slack-backend-addWorkspace (138 kB)
  deleteWorkspace: slack-backend-deleteWorkspace (138 kB)
  getWorkspace: slack-backend-getWorkspace (138 kB)
  getWorkspaces: slack-backend-getWorkspaces (138 kB)
  inviteToWorkspace: slack-backend-inviteToWorkspace (138 kB)
  outWorkspace: slack-backend-outWorkspace (138 kB)
  defaultHandler: slack-backend-defaultHandler (138 kB)
layers:
  pyjwt: arn:aws:lambda:ap-northeast-2:xxxxxxxxx:layer:pyjwt:22

If you want to remove application

serverless remove

HttpApi Specification

Workspace

Create a Workspace

curl -X POST https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/workspace -d '{"workspace_id": "7ea53ab4-7786-4ea5-9e88-79aba53d16f4","channel_name": "test channel","user_email": "test@test.com"}' -H "Content-Type: application/json"

Example output:

{
    "message": "channel created successfully",
    "workspace_name": "testing workspace",
    "workspace_id": "7ea53ab4-7786-4ea5-9e88-79aba53d16f4",
    "channel_id": "ca4028cb-0714-4c52-a45d-cf72f484afe5",
    "type": "channel",
    "users": [
        "test@test.com"
    ],
    "messages": [],
    "createdAt": "1691337253.0484533",
    "updatedAt": "1691337253.0484533"
}

Delete a Workspace

curl -X DELETE https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/workspace/{workspace_id}

Example output:

{"message": {workspace_id} + " delete complete"}

Get Workspace Info

curl https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/workspace/{workspace_id}

Example Result:

{
    "createdAt": "1691426371.0651886",
    "channels": [],
    "SK": "workspace#0e204a25-e8f6-4777-8e81-b1796b50ad9b",
    "admin": "tt13@tesst.com",
    "PK": "workspace#0e204a25-e8f6-4777-8e81-b1796b50ad9b",
    "type": "workspace",
    "workspace_name": "testing1",
    "users": [
        "tt13@tesst.com"
    ],
    "updatedAt": "1691426371.0651886",
    "workspace_id": "0e204a25-e8f6-4777-8e81-b1796b50ad9b"
}

Get Workspaces information to which the User belongs

curl -X GET https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/workspaces/{user_email}"

Example Result:

[
	{
		"id": "bef16dd1-9e67-4ac2-954d-fa55bfd87329", 
		"name": "Test",
		"cnt": 1
	}, 
  {
		"id": "c62b5944-2362-4336-83c0-6a7886eee496", 
		"name": "2", 
		"cnt": 1
	}
]

Invite to Workspace

curl -X PATCH https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/workspace -d '{"workspace_id" : "testing", "user_email": "test123@test.com"}'

Example Result:

[
    "test@gmail.com",
    "test2@naver.com"
]

Out Workspace

curl -X PATCH https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/workspace/out -d '{"workspace_id": "testing","user_email": "test123@test.com"}'

Example Result:

{"message": "workspace out complete"}

Channel

Make a Channel

curl -X POST https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/channel -d '{"workspace_id": "7ea53ab4-7786-4ea5-9e88-79aba53d16f4","channel_name": "test channel","user_email": "test@test.com"}'

Example Result:

{
    "message": "channel created successfully",
    "workspace_name": "testing workspace",
    "workspace_id": "7ea53ab4-7786-4ea5-9e88-79aba53d16f4",
    "channel_id": "ca4028cb-0714-4c52-a45d-cf72f484afe5",
    "type": "channel",
    "users": [
        "test@test.com"
    ],
    "messages": [],
    "createdAt": "1691337253.0484533",
    "updatedAt": "1691337253.0484533"
}

Delete a Channel

curl -X DELETE https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/channel/{workspace_id}/{channel_id} 

Example Result:

{
    "message": {channel_id} + " delete complete"
}

Get a Channel

curl -X GET https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/channel/{workspace_id}/{channel_id} 

Example Result:

{
    "channel_name": "test channel1",
    "workspace_id": "689b2153-19b4-482e-9391-a42f8c1157ce",
    "createdAt": "1691476292.5418136",
    "SK": "channel#5ea91590-ff16-4a95-98c6-2a03b8f5bad1",
    "messages": [],
    "PK": "workspace#689b2153-19b4-482e-9391-a42f8c1157ce",
    "type": "channel",
    "workspace_name": "testing3",
    "users": [
        "tt13@tesst.com"
    ],
    "updatedAt": "1691476292.5418136",
    "channel_id": "5ea91590-ff16-4a95-98c6-2a03b8f5bad1"
}

Get Channels

curl -X DELETE https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/channels/{workspace_id}/{user_email}

Example Result:

[channel1, channel2, channel3]

Invite To Channel

curl -X PATCH https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/channel -d '{"workspace_id": "19e7dda1-2f82-43d7-9edf-ed69ae21ddff","channel_id": "dc619060-294a-4dea-9d18-a606aa95ef15","user_email": "test2@naver.com"}'

Example Result:

["test@gmail.com","test2@naver.com"]

Out Channel

curl -X PATCH https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/channel/out -d '{"workspace_id": "testing","channel_id": "tesing_channel","user_email": "test123@test.com"'

Example Result:

{"message": "channel out complete"}

Message

Get Channel Messages

curl -X GET https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/messages/{workspace_id}/{channel_id}

Example Result:

[
   {
      "message":"hi hi",
      "sender":"jooin2000@naver.com",
      "createdAt":"1692724276.0693274"
   },
   {
      "message":"haa",
      "sender":"jooin2000@naver.com",
      "createdAt":"1692724417.0381713"
   },
   {
      "message":"hi hi",
      "sender":"jooin2000@naver.com",
      "createdAt":"1692724562.023181"
   },
   {
      "message":"hi hi",
      "sender":"jooin2000@naver.com",
      "createdAt":"1692725001.527151"
   }
]

Get Dm Messages

curl -X PATCH https://XXXXXXX.execute-api.ap-northeast-2.amazonaws.com/dm/{sender}/{receiver}

Example Result:

[{"createdAt": 1692441630571, "receiver": "test@gmail.com", "message": "hello !!", "sender": "test2@naver.com"}

WebSocket Specification

Connect

wscat -c wss://xxxxxx.execute-api.ap-northeast-2.amazonaws.com/{stage} -H Authorization:{access_token}

Disconnect

DM Chatting

{
"action": "dm_chat",
"sender": "user1",
"receiver": "user2",
"message": "Hello!!",
"createdAt": "1692441630571"
}

Channel Chatting

{
   "action":"channelChat",
   "message":"hi hi",
   "sender":"jooin2000@naver.com",
   "channel_id":"0f582c82-1bbb-4867-811a-b9d4d1f7b1ef",
   "workspace_id":"a3686811-2fe1-4dc1-b935-11892e3e04f3"
}

Scaling

AWS Lambda

By default, AWS Lambda limits the total concurrent executions across all functions within a given region to 1000. The default limit is a safety limit that protects you from costs due to potential runaway or recursive functions during initial development and testing. To increase this limit above the default, follow the steps in To request a limit increase for concurrent executions.

DynamoDB

When you create a table, you specify how much provisioned throughput capacity you want to reserve for reads and writes. DynamoDB will reserve the necessary resources to meet your throughput needs while ensuring consistent, low-latency performance. You can change the provisioned throughput and increasing or decreasing capacity as needed.

This is can be done via settings in the serverless.yml.

ProvisionedThroughput:
ReadCapacityUnits: 1
WriteCapacityUnits: 1

In case you expect a lot of traffic fluctuation we recommend to checkout this guide on how to auto scale DynamoDB https://aws.amazon.com/blogs/aws/auto-scale-dynamodb-with-dynamic-dynamodb/