Default to second map when no hit in first one

Help!
1

The Goal

Im trying to filter access to certain services to my internal IPs only. I use an acl to determine if traffic is coming from an authorized subnet:

frontend front
    mode http
    acl is_intern src [my IP subnets]
    use_backend %[req.hdr(host),lower,map(/etc/haproxy/maps/hosts_intern.map)] if is_intern
    use_backend %[req.hdr(host),lower,map(/etc/haproxy/maps/hosts_extern.map)]

    default_backend default
  • If traffic is from an internal IP the hosts_intern.map is used.
  • If traffic is from an external IP the hosts_extern.map is used.

The problem:

Traffic for a service in hosts_extern.map coming from an internal IP will go straight to the default_backend.

I could also make entries for those services in hosts_intern.map but I’d like to rather not have redundant entries between both files.

Is there a method for telling HAProxy to look in a second map file if the first one returns no match?

I found this article which under “Map Converters” explains you can pass a second argument to the converter with the backend to use when there is no match in the map. (use_backend %[req.hdr(host),lower,map(/etc/hapee-1.8/maps/hosts.map,be_static)], be_static being the backend in their example).

I tried to substitute that with the hosts_extern.map:

use_backend %[req.hdr(host),lower,map(/etc/haproxy/maps/hosts_intern.map,%[req.hdr(host),lower,map(/etc/haproxy/maps/hosts_extern.map)])] if is_intern

Unfortunately, all it did was break the line entirely.

The default_backend is needed as a catch all, therefore I can not use it for the hosts_extern.map.