Adding redirectParam to add custom callback url

[lokesh-lingarajan]

Issue:
apache#11437

Context:
https://www.pac4j.org/blog/understanding-the-callback-endpoint.html

While using Zeppelin + Knox, knox provides a parameter to add custom callback url
https://medium.com/data-collective/apache-zeppelin-oauth-integration-using-apache-knox-dea2362e3dda
"knoxJwtRealm.redirectParam = originalUrl"

I have used the same name for this new config and overrided the compute method in NoParameterCallbackUrlResolver class.

Works fine in local setup, next step is to test in lab.

[xvrl]

@lokesh-lingarajan can you explain how someone would use this parameters? My understanding based on the examples you gave is that the redirectParam is something that specifies how to extract the redirect URL from the request, and pac4j already has QueryParameterCallbackUrlResolver and PathParameterCallbackUrlResolver that implement the functionality you described above for knox+zeppelin. What you implement here seems to work a little differently, can you clarify?

[lokesh-lingarajan]

@lokesh-lingarajan can you explain how someone would use this parameters? My understanding based on the examples you gave is that the redirectParam is something that specifies how to extract the redirect URL from the request, and pac4j already has QueryParameterCallbackUrlResolver and PathParameterCallbackUrlResolver that implement the functionality you described above for knox+zeppelin. What you implement here seems to work a little differently, can you clarify?

I dont see this as a way to extract url from request rather specify the whole url in cases of setups like we have in our prod, where SSL is terminating at ELB and internal communication is HTTP. So we would use this as follows in our prod

"druid.auth.pac4j.redirectParam=https://localhost:8888/druid-ext/druid-pac4j/callback"

Where although our webserver is running on http, we are overriding the url to https, it also gives users more flexibility is redirecting the url to any custom service to do additional data gathering before hitting the service.

[xvrl]

LGTM, but can we add a test to Pac4jCommonConfigTest to cover this?

[xvrl]

I guess we can close this PR since we no longer need this change?

[lokesh-lingarajan]

Not required anymore, we need to use "druid.server.http.enableForwardedRequestCustomizer" to support druid behind a proxy.