Document OAuth2 Client behind proxy and redirect_uri

[bedla]

Hi,

it would be nice to have mentioned in documentation that forward headers has to be used when app is behind proxy servers to correctly handle OAuth redirections.

• See invalid_redirect_uri_parameter exception while running microservices on separate machines #5270 for details

• See https://docs.spring.io/spring-boot/docs/current/reference/html/howto-embedded-web-servers.html#howto-use-tomcat-behind-a-proxy-server for Spring Boot documentation

• Good place could be around default URL template section https://docs.spring.io/spring-security/site/docs/5.2.0.M4/reference/htmlsingle/#oauth2login-sample-redirect-uri

I could create PR, but I dont know if there is some rules for documentation hyperlinking.

Thx

Ivos

[jgrandja]

Thanks for the report @bedla. I agree, we could improve the documentation by referencing existing documentation related to Forwarded Headers (ForwardedHeaderFilter).

Would you be interested in submitting a PR?

[bedla]

I will, no problem :)

[bedla]

PR here #7325