Hello World Full-Stack Security: Svelte/JavaScript + Phoenix/Elixir

Published on January 20, 2022

Developers can easily secure a full-stack application using Auth0 by Okta. This code sample demonstrates how to implement authentication in a client application built with Svelte and JavaScript, as well as how to implement authorization in an API server built with Phoenix and Elixir. You'll connect the client and server applications to see the full security flow in action!

Let's get started!

Quick Auth0 Set Up

To get started, create an Auth0 account to connect your application with the Auth0 Identity Platform. You can also use any of your existing Auth0 accounts.

Get the Auth0 domain and client ID

• Open the Applications section of the Auth0 Dashboard.

• Click on the Create Application button and fill out the form with the following values:

  • Name: Hello World Client

  • Application Type: Single Page Web Applications

• Click on the Create button.

An Auth0 Application page loads up.

As such, click on the "Settings" tab of your Auth0 Application page, locate the "Application URIs " section, and fill in the following values:

• Allowed Callback URLs: http://localhost:4040/callback

• Allowed Logout URLs: http://localhost:4040

• Allowed Web Origins: http://localhost:4040

Scroll down and click the "Save Changes" button.

Next, locate the "Basic Information" section.

When you enter a value in the input fields present on this page, any code snippet that uses such value updates to reflect it. Using the input fields makes it easy to copy and paste code as you follow along.

As such, enter the "Domain" and "Client ID" values in the following fields to set up your single-page application in the next section:

Get the Auth0 audience

• Open the APIs section of the Auth0 Dashboard.

• Click on the Create API button and fill out the "New API" form with the following values:

  • Name: Hello World Server

  • Identifier: https://hello-world.example.com

• Click on the Create button.

When setting up APIs, we also refer to the API identifier as the Audience value. Store that value in the following field to set up your API server in the next section:

Set Up and Run the Phoenix Project

Ensure that you have Elixir v1.12.3 or higher installed.

Start by cloning the Phoenix project:

git clone https://github.com/auth0-developer-hub/api_phoenix_elixir_hello-world.git

Make the project directory your current working directory:

cd api_phoenix_elixir_hello-world

Then, check out the basic-authorization branch, which holds all the code related to implementing token-based authorization to protect resources in a Phoenix API:

git checkout basic-authorization

Install the hex package manager if you don't have it already in your machine:

mix local.hex

Next, install the Phoenix project dependencies:

mix deps.get

Run the following command to generate a random secret key for Phoenix:

mix phx.gen.secret

Store the output from the command above in the following field:

Now, create a .env file under the project directory and populate it as follows:

PORT=6060
CLIENT_ORIGIN_URL=http://localhost:4040
AUTH0_DOMAIN=AUTH0-DOMAIN
AUTH0_AUDIENCE=AUTH0-AUDIENCE
SECRET_KEY_BASE=KEY-VALUE

Execute the following command to run the Phoenix API server:

mix phx.server

Alternatively, you can also run the server inside the Elixir interactive shell (IEx) by running the following command instead:

iex -S mix phx.server

Set Up and Run the Svelte Project

Start by cloning the project into your local machine:

git clone https://github.com/auth0-developer-hub/spa_svelte_javascript_hello-world.git

Make the project directory your current working directory:

cd spa_svelte_javascript_hello-world

Then, check out the basic-authentication-with-api-integration branch, which holds all the Svelte code related to implementing user login with Auth0 and requesting protected resources from an API:

git checkout basic-authentication-with-api-integration

Next, install the Svelte project dependencies:

npm install

Once you have access to the Svelte project, create a .env file under the project directory and populate it as follows:

VITE_AUTH0_DOMAIN=AUTH0-DOMAIN
VITE_AUTH0_CLIENT_ID=AUTH0-CLIENT-ID
VITE_AUTH0_CALLBACK_URL=http://localhost:4040/callback
VITE_API_SERVER_URL=http://localhost:6060
VITE_AUTH0_AUDIENCE=AUTH0-AUDIENCE

Run the Svelte application by issuing the following command:

npm run dev

You can now visit http://localhost:4040/ to access the application.

There's something missing in this Svelte code sample. There's no login or sign-up forms!

When you use Auth0, you don't need to build any login or sign-up forms! Your users can log in to your application through a page hosted by Auth0, which provides a secure, standards-based login experience. You can customize the Auth0 login page with your branding and enable different authentication methods, such as logging in with a username/password combination or a social provider like Facebook or Google.

Once you log in, visit the protected "Profile" page (http://localhost:4040/profile) to see all the user profile information that Auth0 securely shares with your application using ID tokens.

Then, visit the "Protected" page (http://localhost:4040/protected) or the "Admin" page (http://localhost:4040/admin) to practice requesting protected resources from an external API server using access tokens.