Exclude Pulp 2 API calls from being handled by Pulp 3

fixes: #7481
https://pulp.plan.io/issues/7481

CHANGES/7481.bugfix

@@ -0,0 +1 @@
+Fixed Apache config bug that prevented Pulp 2 API from being accessible.

docs/index.md

@@ -21,6 +21,10 @@ must be one of these currently supported operating systems:
 * Debian Buster (needs `allow_world_readable_tmpfiles = True` in ansible.cfg)
 * Fedora 30 or later
 
+The managed node cannot provide any other service on the same hostname as Pulp's API. The only
+exception is Pulp 2. The RESP APIs for Pulp 2 and Pulp 3 can be served on the same hostname as
+long as the `apache` webserver is deployed for both.
+
 Ansibles Python interpreter must have the package installed:
 * psycopg2
 * firewall (if firewalld should be configured; you can disable that with `pulp_configure_firewall=false`)

roles/pulp_webserver/templates/pulp-vhost.conf.j2

@@ -14,8 +14,8 @@ Define pulp-api {{ pulp_api_bind }}
   ProxyRequests Off
   ProxyPreserveHost Off
 
-  ProxyPass /pulp/api http://${pulp-api}/pulp/api
-  ProxyPassReverse /pulp/api http://${pulp-api}/pulp/api
+  ProxyPass /pulp/api/v3 http://${pulp-api}/pulp/api/v3
+  ProxyPassReverse /pulp/api/3 http://${pulp-api}/pulp/api/v3
 
   ProxyPass /auth/login/ http://${pulp-api}/auth/login/
   ProxyPassReverse /auth/login/ http://${pulp-api}/auth/login/
@@ -26,6 +26,8 @@ Define pulp-api {{ pulp_api_bind }}
   IncludeOptional pulp/*.conf
 
   # static files are served through whitenoise - http://whitenoise.evans.io/en/stable/
+  # exclude all pulp v2 api calls
+  ProxyPassMatch ^/pulp/api/v2 !
   ProxyPass / http://${pulp-api}/
   ProxyPassReverse / http://${pulp-api}/
 
@@ -65,8 +67,8 @@ Define pulp-api {{ pulp_api_bind }}
   ProxyRequests Off
   ProxyPreserveHost Off
 
-  ProxyPass /pulp/api http://${pulp-api}/pulp/api
-  ProxyPassReverse /pulp/api http://${pulp-api}/pulp/api
+  ProxyPass /pulp/api/v3 http://${pulp-api}/pulp/api/v3
+  ProxyPassReverse /pulp/api/v3 http://${pulp-api}/pulp/api/v3
 
   ProxyPass /auth/login/ http://${pulp-api}/auth/login/
   ProxyPassReverse /auth/login/ http://${pulp-api}/auth/login/
@@ -78,6 +80,8 @@ Define pulp-api {{ pulp_api_bind }}
 
   # most pulp static files are served through whitenoise
   # http://whitenoise.evans.io/en/stable/
+  # exclude all pulp v2 api calls
+  ProxyPassMatch ^/pulp/api/v2 !
   ProxyPass / http://${pulp-api}/
   ProxyPassReverse / http://${pulp-api}/