Developers can easily secure a full-stack application using Auth0. 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 Spring WebFlux and Java. 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
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Open the Applications section of the Auth0 Dashboard.
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Click on the Create Application button and fill out the form with the following values:
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Name:
Hello World Client -
Application Type: Single Page Web Applications
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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:
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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
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Open the APIs section of the Auth0 Dashboard.
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Click on the Create API button and fill out the "New API" form with the following values:
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Name:
Hello World Server -
Identifier:
https://hello-world.example.com
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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 Spring WebFlux Project
Start by cloning the Spring WebFlux project:
git clone https://github.com/auth0-developer-hub/api_spring-webflux_java_hello-world.git
Make the project directory your current working directory:
cd api_spring-webflux_java_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 Spring WebFlux API:
git checkout basic-authorization
Install the Spring WebFlux project dependencies using Gradle:
./gradlew dependencies --write-locks
Now, create a .env file under the project directory and populate it as follows:
PORT=6060CLIENT_ORIGIN_URL=http://localhost:4040OKTA_OAUTH2_ISSUER=https://AUTH0-DOMAIN/OKTA_OAUTH2_AUDIENCE=AUTH0-AUDIENCE
Execute the following command to run the Spring WebFlux API server:
./gradlew bootRun
Optional: Enable hot swapping
Spring Boot supports hot swapping. The spring-boot-devtools module includes support for restarting your application automatically as your project code changes.
You have two options to use Spring Boot hot swapping:
Use Spring Tools
You can install Spring Tools in your project. Then, whenever you run the Spring server from your IDE, hot swapping will be enabled.
Spring Tools will handle watching project files, recompiling, and restarting the server as you make code changes in your project.
Using the Gradle Wrapper
You can run the Gradle Wrapper in a terminal application as follows:
- Open a terminal window to watch and compile the Spring Boot project:
./gradlew compileJava -t
- Open a second terminal window to start the server:
./gradlew bootRun
Running those Gradle tasks in parallel enables Spring Boot hot swapping. The server will automatically restart when you make code changes in your project.
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-DOMAINVITE_AUTH0_CLIENT_ID=AUTH0-CLIENT-IDVITE_AUTH0_CALLBACK_URL=http://localhost:4040/callbackVITE_API_SERVER_URL=http://localhost:6060VITE_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.