Serverless TODO

This project is part of the Cloud Developer Nanodegree. The goal of this project to implement a simple TODO application using AWS Lambda and Serverless framework.

Functionality of the application

This application allows to create/remove/update/fetch 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
• userId (string) - the user id that created this todo 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, the following functions have been configured:

• Auth - this function implements a custom authorizer for API Gateway that is attached to all other functions.

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

It returns data that looks like this:

{
  "items": [
    {
      "todoId": "123",
      "userId": "abc123",
      "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",
      "userId": "def456",
      "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"
    },
  ]
}

The todo items are sorted by the createdAt attribute in descending order.

• CreateTodo - create 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 to be created in JSON format that looks like this:

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

It returns a new TODO item that looks like this:

{
  "item": {
    "todoId": "123",
    "userId": "abc123",
    "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 send 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 has to 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"
}

• SortTodosByDueDate - returns all TODOs for the current user sorted by the dueDate in the ascending order.

All functions are already connected to appropriate events from API Gateway.

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

The serverless.yml file includes all of these functions as well as a DynamoDB table and a S3 bucket in the resources.

Authentication

This app is using Auth0 to implement authentication. The configuration of the "domain" and "client id" are available on the client/src/config.ts file.

How to run the application

Prerequisite

1. Install serverless npm install -g serverless

2. Set up a new user in IAM named "serverless" with Programmatic access and with AdministratorAccess policy attached and save the access key and secret key.

3. Configure serverless to use the AWS credentials you just set up: sls config credentials --provider aws --key YOUR_ACCESS_KEY --secret YOUR_SECRET_KEY --profile serverless

Backend

To deploy this application, use the following commands: sls deploy -v

Frontend

To have the application running on your local machine, run the following commands:

cd client
npm install
npm run start

Screenshots

Resource Creation

• DynamoDB to store TODO item with userId, todoId, done, dueDate, attachmentUrl, createdAt attributes

• s3 Bucket to store file attached to TODO item

Lambda Functions

Observability

• CloudWatch to monitors logs

• X-Ray to record metrics