rgw-loadbalancer: Update haproxy.cfg.j2

haproxy gets an AVC when configured to connect to port 8081

This commit adds a snippet regarding haproxy in a selinux environment

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1923890

Signed-off-by: Kaleb S KEITHLEY <kkeithle@redhat.com>
(cherry picked from commit 9e7f22a071)

roles/ceph-rgw-loadbalancer/templates/haproxy.cfg.j2

@@ -40,6 +40,18 @@ frontend rgw-frontend
 {% endif %}
     default_backend rgw-backend
 
+# when running in an selinux environment, selinux restricts the ports that haproxy can
+# connect to to:
+#  * 80, 81, 443, 488, 8008, 8009, 8443, 9000 (http_port_t) and,
+#  * 8080, 8118, 8123, 10001-10010 (http_cache_port_t)
+#
+# Practically speaking, it would be preferable (and perhaps easier) to configure the
+# rgw daemons to listen on ports 10001-10010 and configure haproxy here to match.
+#
+# Alternatively you can add other unused ports to http_port_t or http_cache_port_t
+# with, e.g.: `semanage port -a -t http_cache_port_t -p tcp 8085`
+# (Note that ports 8081-8084 are already taken and can't be used for haproxy.)
+#
 backend rgw-backend
     option forwardfor
     balance static-rr