Gitea
Gitea supports OAuth2/OIDC for sign-in. This guide configures Casdoor as the identity provider.
Prerequisites: Gitea installed and an admin account. See install Gitea. The first registered user is admin if you did not create one during install.
1. Create a Casdoor application
Create an application in Casdoor. Note the Client ID and Client Secret. Do not set the callback URL yet; it depends on Gitea’s auth source name (step 3).

2. Add authentication source in Gitea
Log in as admin → Site Administration → Authentication Source.

Click Add Authentication Source. Set Authentication Type to OAuth2 and OAuth2 Provider to OpenID Connect. Set a name for this source and remember it (used for the callback URL). Enter the Client ID and Client Secret from step 1. Set the OpenID Connect Auto Discovery URL to https://<casdoor-endpoint>/.well-known/openid-configuration. Save.

3. Set the callback URL in Casdoor
In the Casdoor application, add this redirect URL:
<gitea-endpoint>/user/oauth2/<authentication-source-name>/callback
Replace <authentication-source-name> with the name you set in Gitea (e.g. casdoor).
4. Test
Sign out of Gitea. On the login page you should see:

Appuyez sur le bouton 'se connecter avec openid' et vous serez redirigé vers la page de connexion Casdoor.
Après la connexion, vous verrez ceci :
Suivez les instructions et liez le compte Casdoor avec un nouveau compte Gitea ou un compte existant.
Ensuite, tout devrait fonctionner correctement.