oauth2-proxy seems to sanitize / unescape parts of the proxied url and send a redirect when the backend expects the url exactly as specified. This breaks some backends that use url encoded parameters.
Our current example is a rabbitmq-server admin frontend. RabbitMQ by default has a virtual host called "/" and generates some urls in the form of:
/api/vhosts/%2F/permissions

oauth2-proxy will then send me a HTTP 301 to /api/vhosts/permissions for this url which the backend then not recognizes.

Expected Behavior

No redirect / rewriting of urls from oauth2-proxy

Current Behavior

Calling /api/vhosts/%2F/permissions results in a HTTP 301 to /api/vhosts/permissions from oauth2-proxy

Possible Solution

Oauth2-proxy should not touch / rewrite / redirect the specified url when passing to the backend proxy in any way or at least have such behaviour configurable.

Steps to Reproduce (for bugs)

Issue a request to an url like:
/FOO/%2F/BAR/
and no matter what's behine the proxy you will receive a HTTP 301 to
/FOO/BAR/

• Version used: 6.1.1