Serverless TODO

This is a simple TODO application using AWS Lambda and Serverless framework.

Functionality of the application

This application allows creating/removing/updating/fetching TODO items. Each TODO item can optionally have an attachment image. Each user only has access to TODO items that he/she has created.

TODO items

The application stores TODO items, and each TODO item contains the following fields:

• todoId (string) - a unique id for an item
• createdAt (string) - date and time when an item was created
• name (string) - name of a TODO item (e.g. "Change a light bulb")
• dueDate (string) - date and time by which an item should be completed
• done (boolean) - true if an item was completed, false otherwise
• attachmentUrl (string) (optional) - a URL pointing to an image attached to a TODO item

Functions implemented

To implement this project, you need to implement the following functions and configure them in the serverless.yml file:

• Auth - this function implements a custom authorizer for API Gateway that is also used by all other functions.

• GetTodos - returns all TODOs for a current user. A user id can be extracted from a JWT token that is sent by the frontend

It returns data that looks like this:

{
  "items": [
    {
      "todoId": "123",
      "createdAt": "2019-07-27T20:01:45.424Z",
      "name": "Buy milk",
      "dueDate": "2019-07-29T20:01:45.424Z",
      "done": false,
      "attachmentUrl": "http://example.com/image.png"
    },
    {
      "todoId": "456",
      "createdAt": "2019-07-27T20:01:45.424Z",
      "name": "Send a letter",
      "dueDate": "2019-07-29T20:01:45.424Z",
      "done": true,
      "attachmentUrl": "http://example.com/image.png"
    },
  ]
}

• CreateTodo - creates a new TODO for a current user. A shape of data send by a client application to this function can be found in the CreateTodoRequest.ts file

It receives a new TODO item that's created in JSON format and looks like this:

{
  "createdAt": "2019-07-27T20:01:45.424Z",
  "name": "Buy milk",
  "dueDate": "2019-07-29T20:01:45.424Z",
  "done": false,
  "attachmentUrl": "http://example.com/image.png"
}

It should return a new TODO item that looks like this:

{
  "item": {
    "todoId": "123",
    "createdAt": "2019-07-27T20:01:45.424Z",
    "name": "Buy milk",
    "dueDate": "2019-07-29T20:01:45.424Z",
    "done": false,
    "attachmentUrl": "http://example.com/image.png"
  }
}

• UpdateTodo - updates a TODO item created by a current user. A shape of data sent by a client application to this function can be found in the UpdateTodoRequest.ts file

It receives an object that contains three fields that can be updated in a TODO item:

{
  "name": "Buy bread",
  "dueDate": "2019-07-29T20:01:45.424Z",
  "done": true
}

The id of an item that should be updated is passed as a URL parameter.

It returns an empty body.

• DeleteTodo - deletes a TODO item created by a current user. Expects an id of a TODO item to remove.

It returns an empty body.

• GenerateUploadUrl - returns a pre-signed URL that can be used to upload an attachment file for a TODO item.

It returns a JSON object that looks like this:

{
  "uploadUrl": "https://s3-bucket-name.s3.eu-west-2.amazonaws.com/image.png"
}

All functions are connected to appropriate events from API Gateway.

An id of a user can be extracted from a JWT token passed by a client.

Frontend

The client folder contains a web application that can use the API that should be developed in the project.

The only file that you need to edit is the config.ts file in the client folder. This file configures your client application just as it was done in the course and contains an API endpoint and Auth0 configuration:

const apiId = '...' API Gateway id
export const apiEndpoint = `https://${apiId}.execute-api.us-east-1.amazonaws.com/dev`

export const authConfig = {
  domain: '...',    // Domain from Auth0
  clientId: '...',  // Client id from an Auth0 application
  callbackUrl: 'http://localhost:3000/callback'
}

Authentication

To implement authentication in your application, you would have to create an Auth0 application and copy "domain" and "client id" to the config.ts file in the client folder. We recommend using asymmetrically encrypted JWT tokens.

Logging

The app is configured Winston with a logger that creates JSON formatted log statements. It writes log messages like this:

import { createLogger } from '../../utils/logger'
const logger = createLogger('auth')

// You can provide additional information with every log statement
// This information can then be used to search for log statements in a log storage system
logger.info('User was authorized', {
  // Additional information stored with a log statement
  key: 'value'
})

How to run the application

Backend

To deploy an application run the following commands:

cd backend
npm install
sls deploy -v

Frontend

To run a client application first edit the client/src/config.ts file to set correct parameters. And then run the following commands:

cd client
npm install
npm run start

This should start a development server with the React application that will interact with the serverless TODO application.