First things first, let's get the Supabase CLI installed. You can do this with npm:

npm install -g supabase

Next up, we need to initialize your Supabase project. Navigate to the directory where you want your project and run:

supabase init

Now, let's get that Supabase database up and running. Just type:

supabase start

Make sure you've got Docker installed and running, as this step needs it.

To integrate OpenID Connect, you'll need to get the OIDC credentials from your identity provider. This usually means a client ID and client secret.

Head over to the Supabase dashboard and go to the Authentication section.

• Click on External Auth providers.
• Pick OpenID Connect.
• Fill in the details:
• Client ID: The client ID you got in Step 4.
• Client Secret: The client secret from Step 4.
• Discovery URL: Usually for finding the provider's configuration.
• Authorize URL: The URL endpoint for authorization.
• Token URL: The URL endpoint for token exchange.
• Redirect URL: Set this to follow Supabase's predefined redirect URL.

Store those important credentials in environment variables to avoid hardcoding them. You can set these in a .env file:

SUPABASE_CLIENT_ID=your_oidc_client_id
SUPABASE_CLIENT_SECRET=your_oidc_client_secret

Make sure these variables are loaded into the environment where your Supabase app runs.

Update the Supabase configuration file, usually found as supabase/config/auth.json or something similar, with the OIDC settings:

{
  "site_url": "your_site_url",
  "external": {
    "oidc": {
      "client_id": "your_oidc_client_id",
      "client_secret": "your_oidc_client_secret",
      "discovery_url": "provider_discovery_url",
      "authorize_url": "provider_authorize_url",
      "token_url": "provider_token_url",
      "redirect_url": "your_supabase_redirect_url"
    }
  }
}

After making those changes, restart Supabase to apply them:

supabase stop
supabase start

Time to test the OpenID Connect integration. Try logging in through the OIDC provider from your app's authentication flow.

Go to your app and start the login process. Make sure it redirects to the OIDC provider, lets you sign in, and then redirects back, logging you into Supabase.

If you run into any issues, check the Supabase logs and make sure all configurations are correct. Keep an eye on user login attempts to ensure everything's working smoothly and handle any errors from the logs effectively.