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Serverless TODO

In this project I develop and deploy a simple “TODO” application using AWS Lambda and Serverless framework. This application will allow users to create/remove/update/get TODO items. 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 should implement a custom authorizer for API Gateway that should be added to all other functions.
  • GetTodos – should return all TODOs for a current user.
  • CreateTodo – should 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
  • UpdateTodo – should update 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
  • DeleteTodo – should delete a TODO item created by a current user. Expects an id of a TODO item to remove.
  • GenerateUploadUrl – returns a presigned url that can be used to upload an attachment file for a TODO item.

All functions are already connected to appriate events from API gateway

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

You also need to add any necessary resources to the resources section of the serverless.yml file such as DynamoDB table and and S3 bucket.

Deploy Backend

                cd backend

              npm update --save

              npm audit fix


              npm install --save-dev serverless-iam-roles-per-function@next 

              serverless deploy --verbose



Lambda Functions

  • Auth: serverless-dev-Auth
  • GetTodos: serverless-dev-GetTodos
  • CreateTodo: serverless-dev-CreateTodo
  • UpdateTodo: serverless-dev-UpdateTodo
  • DeleteTodo: serverless-dev-DeleteTodo
  • GenerateUploadUrl: serverless-dev-GenerateUploadUrl


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AWS Cloud Formation

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

To use it please edit the config.ts file in the client folder:

const apiId = '...' API Gateway id
export const apiEndpoint = `https://${apiId}`

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


To store TODO items you might want to use a DynamoDB table with local secondary index(es). A create a local secondary index you need to a create a DynamoDB resource like this:

  Type: AWS::DynamoDB::Table
      - AttributeName: partitionKey
        AttributeType: S
      - AttributeName: sortKey
        AttributeType: S
      - AttributeName: indexKey
        AttributeType: S
      - AttributeName: partitionKey
        KeyType: HASH
      - AttributeName: sortKey
        KeyType: RANGE
    BillingMode: PAY_PER_REQUEST
    TableName: ${self:provider.environment.TODOS_TABLE}
      - IndexName: ${self:provider.environment.INDEX_NAME}
          - AttributeName: partitionKey
            KeyType: HASH
          - AttributeName: indexKey
            KeyType: RANGE
          ProjectionType: ALL # What attributes will be copied to an index

To query an index you need to use the query() method like:

await this.dynamoDBClient
    TableName: 'table-name',
    IndexName: 'index-name',
    KeyConditionExpression: 'paritionKey = :paritionKey',
    ExpressionAttributeValues: {
      ':paritionKey': partitionKeyValue

Deploy 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

Working Todo


Blank Todo


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


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