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Amazon Cognito Authentication

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What you’ll learn

  • Programmatically authenticate with Amazon Cognito via a custom Cypress command
  • Adapting your Amazon Cognito application for programmatic authentication during testing
Why authenticate programmatically?

Typically, logging in a user within your app by authenticating via a third-party provider requires visiting login pages hosted on a different domain. Since each Cypress test is limited to visiting domains of the same origin, we can subvert visiting and testing third-party login pages by programmatically interacting with the third-party authentication API to login a user.

What is Amazon Cognito?

Amazon Cognito is an authentication provider apart of Amazon Web Services (AWS).

It “lets you add user sign-up, sign-in, and access control to your web and mobile apps quickly and easily” and “scales to millions of users and supports sign-in with social identity providers, such as Facebook, Google, and Amazon, and enterprise identity providers via SAML 2.0.”

Programmatic Authentication with Amazon Cognito

The documentation for Amazon Cognito recommends using the AWS Amplify Framework Authentication Library from the AWS Amplify Framework to interact with a deployed Amazon Cognito instance.

Using the AWS Amplify Framework Authentication Library, we are able to programmatically drive the creation and authentication of users against a fully deployed back end.

This illustrates the limited code from the AWS Amplify Framework needed to programmatically log an existing a user into an application.

// Add 'aws-amplify' library into your application

// Configure Auth category with your Amazon Cognito credentials
Amplify.configure({
  Auth: {
    identityPoolId: 'XX-XXXX-X:XXXXXXXX-XXXX', // Amazon Cognito Identity Pool ID
    region: 'XX-XXXX-X', // Amazon Cognito Region
  }
})

// Call Auth.signIn with user credentials
Auth.signIn(username, password)
  .then((user) => console.log(user))
  .catch((err) => console.log(err))

Amazon Cognito Setup

If not already setup, you will need to create an account with Amazon Web Services (AWS).

An Amazon Cognito integration is available in the Cypress Real World App.

Clone the Cypress Real World App and install the AWS Amazon Amplify CLI as follows:

npm install -g @aws-amplify/cli

The Cypress Real World App is configured with an optional
Amazon Cognito instance via the AWS Amplify Framework Authentication Library.

The AWS Amazon Amplify CLI is used to provision the Amazon Web Services (AWS) infrastructure needed to configure your environment and cloud resources.

First, run the amplify init command to initialize the Cypress Real World App. This will provision the project with your AWS credentials.

amplify init

Next, run the amplify push command to create the Amazon Cognito resources in the cloud:

amplify push
Note

Use the yarn dev:cogntio command when starting the Cypress Real World App.

Setting Amazon Cognito app credentials in Cypress

First, we need to configure Cypress to use the AWS Cognito environment variables set in .env inside of the cypress/plugins/index.js file. In addition, we are using the aws-exports.js supplied during the AWS Amplify CLI build process.

// cypress/plugins/index.js
// initial imports ...

const awsConfig = require(path.join(__dirname, '../../aws-exports-es5.js'))

dotenv.config()

export default (on, config) => {
  // ...
  config.env.cognito_username = process.env.AWS_COGNITO_USERNAME
  config.env.cognito_password = process.env.AWS_COGNITO_PASSWORD
  config.env.awsConfig = awsConfig.default

  // plugins code ...

  return config
}

Custom Command for Amazon Cognito Authentication

Next, we’ll write a command to perform a programmatic login into Amazon Cognito and set items in localStorage with the authenticated users details, which we will use in our application code to verify we are authenticated under test.

In this loginByCognitoApi command, we call Auth.signIn, then use that response to set the items inside of localStorage for the UI to know that our user is logged into the application.

// cypress/support/auth-provider-commands/cognito.ts

import Amplify, { Auth } from 'aws-amplify'

Amplify.configure(Cypress.env('awsConfig'))

// Amazon Cognito
Cypress.Commands.add('loginByCognitoApi', (username, password) => {
  const log = Cypress.log({
    displayName: 'COGNITO LOGIN',
    message: [`🔐 Authenticating | ${username}`],
    // @ts-ignore
    autoEnd: false,
  })

  log.snapshot('before')

  const signIn = Auth.signIn({ username, password })

  cy.wrap(signIn, { log: false }).then((cognitoResponse) => {
    const keyPrefixWithUsername = `${cognitoResponse.keyPrefix}.${cognitoResponse.username}`

    window.localStorage.setItem(
      `${keyPrefixWithUsername}.idToken`,
      cognitoResponse.signInUserSession.idToken.jwtToken
    )

    window.localStorage.setItem(
      `${keyPrefixWithUsername}.accessToken`,
      cognitoResponse.signInUserSession.accessToken.jwtToken
    )

    window.localStorage.setItem(
      `${keyPrefixWithUsername}.refreshToken`,
      cognitoResponse.signInUserSession.refreshToken.token
    )

    window.localStorage.setItem(
      `${keyPrefixWithUsername}.clockDrift`,
      cognitoResponse.signInUserSession.clockDrift
    )

    window.localStorage.setItem(
      `${cognitoResponse.keyPrefix}.LastAuthUser`,
      cognitoResponse.username
    )

    window.localStorage.setItem('amplify-authenticator-authState', 'signedIn')
    log.snapshot('after')
    log.end()
  })

  cy.visit('/')
})

Finally, we can use our loginByCognitoApi command in at test. Below is our test to login as a user via Amazon Cognito, complete the onboarding process and logout.

The runnable version of this test is in the Cypress Real World App.

describe('Cognito', function () {
  beforeEach(function () {
    cy.task('db:seed')
    cy.loginByOktaApi(Cypress.env('cognito_username'), Cypress.env('cognito_password'))
  })

  it('shows onboarding', function () {
    cy.contains('Get Started').should('be.visible')
  })
})

Adapting an Amazon Cognito App for Testing

The Cypress Real World App is used and provides configuration and runnable code for both the React SPA and the Express back end.

The front end uses the AWS Amplify Framework Authentication Library. The back end uses the express-jwt to validate JWTs from Amazon Cognito.

Adapting the back end

In order to validate API requests from the frontend, we install express-jwt and jwks-rsa and configure validation for JWT’s from Amazon Cognito.

// backend/helpers.ts
// ... initial imports
import jwt from 'express-jwt'
import jwksRsa from 'jwks-rsa'

// ...

const awsCognitoJwtConfig = {
  secret: jwksRsa.expressJwtSecret({
    jwksUri: `https://cognito-idp.${awsConfig.aws_cognito_region}.amazonaws.com/${awsConfig.aws_user_pools_id}/.well-known/jwks.json`,
  }),

  issuer: `https://cognito-idp.${awsConfig.aws_cognito_region}.amazonaws.com/${awsConfig.aws_user_pools_id}`,
  algorithms: ['RS256'],
}

export const checkCognitoJwt = jwt(awsCognitoJwtConfig).unless({ path: ['/testData/*'] })

Once this helper is defined, we can use globally to apply to all routes:

// backend/app.ts
// initial imports ...
import { checkCognitoJwt } from './helpers'

// ...

if (process.env.REACT_APP_AWS_COGNITO) {
  app.use(checkCognitoJwt)
}

// routes ...

Adapting the front end

We need to update our front end React app to allow for authentication with Amazon Cognito using the AWS Amplify Framework Authentication Library.

First, we create a AppCognito.tsx container, based off of the App.tsx component.

A useEffect hook is added to get the access token for the authenticated user and send an COGNITO event with the user and token objects to work with the existing authentication layer (authMachine.ts). We use the AmplifyAuthenticator component to provide the login form from Amazon Cognito.

// src/containers/AppOkta.tsx
// initial imports ...
import Amplify from "aws-amplify";
import { AmplifyAuthenticator, AmplifySignUp, AmplifySignIn } from "@aws-amplify/ui-react";
import { AuthState, onAuthUIStateChange } from "@aws-amplify/ui-components";

import awsConfig from "../aws-exports";

Amplify.configure(awsConfig);

// ...

const AppCognito: React.FC = () => {

  // ...

  useEffect(() => {
    return onAuthUIStateChange((nextAuthState, authData) => {
      if (nextAuthState === AuthState.SignedIn) {
        authService.send("COGNITO", { user: authData });
      }
    });
  }, []);

  // ...

  return isLoggedIn ? (
    // ...
  ) : (
    <Container component="main" maxWidth="xs">
      <CssBaseline />
      <AmplifyAuthenticator usernameAlias="email">
        <AmplifySignUp slot="sign-up" usernameAlias="email" />
        <AmplifySignIn slot="sign-in" usernameAlias="email" />
      </AmplifyAuthenticator>
    </Container>
  );
};

export default AppCognito;
Try it out

The complete AppCognito.tsx component is in the Cypress Real World App.

Next, we update our entry point (index.tsx) to use our AppCognito.tsx component.

// src/index.tsx
// ... initial imports
import AppCognito from "./containers/AppCognito"

// ...

if (process.env.REACT_APP_AWS_COGNITO) {
  ReactDOM.render(
    <Router history={history}>
      <ThemeProvider theme={theme}>
        <AppCognito />
      </ThemeProvider>
    </Router>,
    document.getElementById("root")
  );
}