I've placed my keycloak server behind apache proxy:
ProxyRequests On
ProxyVia On
ProxyPreserveHost On
SSLProxyEngine On
SSLProxyCheckPeerCN on
SSLProxyCheckPeerExpire on
<LocationMatch "/auth/">
    ProxyPass http://keycloak:8090/auth/ Keepalive=On
</LocationMatch>
ProxyPassReverse "/auth/" "http://keycloak:8090/auth/"
I've succesfully told my keycloak on javascript side to use /auth for authentication:
{
  "realm" : "local",
  "auth-server-url" : "/auth",
  "ssl-required" : "external",
  "resource" : "client-local",
  "public-client" : true
}
I've managed to log in, but after making server request, the filter (org.keycloak.jaxrs.JaxrsBearerTokenFilterImpl from keycloak-jaxrs-oath-client-4.0.0.FINAL) is throwing exception: 
WWW-Authenticate: Bearer realm="local", error="invalid_token", error_description="Invalid token issuer. Expected 'http://keycloak:8090/auth/realms/local', but was 'http://localhost/auth/realms/local'"
What I'm missing here? I've expected, that the reverse proxy would be transparent for the keycloak... I can't find the option to add localhost to valid issuers in keycloak administration panel either...
How can I bring that setup to work?