leptos/examples/sso_auth_axum/README.md

# Leptos SSO Authenticated Email Display App with Axum

## Overview
This project demonstrates various methods of implementing Single Sign-On (SSO) authorization using OAuth, specifically with the OAuth2 library. The primary focus is on the Authorization Code Grant flow.

### Process Flow
1. **Initiating Sign-In:** When a user clicks the 'Sign In With {THIRD PARTY SERVICE}' button, the request is sent to a server function. This function retrieves an authorization URL from the third-party service.

2. **CSRF Token Handling:** During the URL fetch, a CSRF_TOKEN is generated and confirmed by the service to mitigate Cross-Site Request Forgery attacks. Learn more about CSRF [here](https://en.wikipedia.org/wiki/Cross-site_request_forgery). This token is stored on our server.

3. **User Redirection:** Post-login, users are redirected to our server with a URL formatted as follows:  
`http://your-redirect-uri.com/callback?code=AUTHORIZATION_CODE&state=CSRF_TOKEN`
Note: Additional parameters like Scope and Client_ID may be included by the service.

4. **Token Acquisition:** The 'code' parameter in the URL is not the actual service token. Instead, it's used to fetch the token. We verify the CSRF_TOKEN in the URL against our server's stored token for security.

5. **Access Token Usage:** With a valid CSRF_TOKEN, we use the AUTHORIZATION_CODE in an HTTP Request to the third-party service. The response typically includes:
- An `access token`
- An `expires_in` value (time in seconds until token expiration)
- A `refresh token` (used to renew the access token)

6. **Email Retrieval and Display:** The access token allows us to retrieve the user's email. This email is then displayed in our Email Display App.

7. **Session Management:** The `expires_in` value is sent to the client. The client uses this to set a timeout, ensuring that if the session is still active (the window hasn't been closed), it automatically triggers a token refresh when required.



## Client Side Rendering
This example cannot be built as a trunk standalone CSR-only app. Only the server may directly connect to the database.

## Server Side Rendering with cargo-leptos
cargo-leptos is now the easiest and most featureful way to build server side rendered apps with hydration. It provides automatic recompilation of client and server code, wasm optimisation, CSS minification, and more! Check out more about it [here](https://github.com/akesson/cargo-leptos)

## Env Vars
Commands that run the program, cargo leptos watch, cargo leptos serve, cargo run etc... All need the following Environment variables
G_AUTH_CLIENT_ID : This is the client ID given to you by google.
G_AUTH_SECRET : This is the secret given to you by google.
NGROK : this is the ngrok endpoint you get when you run ngrok http 3000

## Ngrok Google Set Up
After running your app, run
```bash
ngrok http 3000
```
Then use google api's and services, go to credentials, create credentials, add your app name, and use the ngrok url as the origin
and use the ngrok url with /g_auth as the redirect url. That will look like this `https://362b-24-34-20-189.ngrok-free.app/g_auth`
Save you client ID and secret given to you by google. Use them as Envars when you run the program as below
```bash
REDIRECT_URL={ngrok_redirect_url} G_AUTH_CLIENT_ID={google_credential_client_id} G_AUTH_SECRET={google_credential_secret} {your command here...}
```

1. Install cargo-leptos
```bash
cargo install --locked cargo-leptos
``` 
2. Build the site in watch mode, recompiling on file changes
```bash
cargo leptos watch
```

Open browser on [http://localhost:3000/](http://localhost:3000/)

3. When ready to deploy, run
```bash
cargo leptos build --release
```

## Server Side Rendering without cargo-leptos
To run it as a server side app with hydration, you'll need to have wasm-pack installed.

0. Edit the `[package.metadata.leptos]` section and set `site-root` to `"."`. You'll also want to change the path of the `<StyleSheet / >` component in the root component to point towards the CSS file in the root. This tells leptos that the WASM/JS files generated by wasm-pack are available at `./pkg` and that the CSS files are no longer processed by cargo-leptos. Building to alternative folders is not supported at this time. You'll also want to edit the call to `get_configuration()` to pass in `Some(Cargo.toml)`, so that Leptos will read the settings instead of cargo-leptos. If you do so, your file/folder names cannot include dashes.
1. Install wasm-pack
```bash
cargo install wasm-pack
```
2. Build the Webassembly used to hydrate the HTML from the server
```bash
wasm-pack build --target=web --debug --no-default-features --features=hydrate
```
3. Run the server to serve the Webassembly, JS, and HTML 
```bash
cargo run --no-default-features --features=ssr
```