HAProxy not recognizing host headers?

Question

I have been trying to configure HAProxy to send traffic to different backend servers based on hostnames. I tried using the directions found in How to divert traffic based on hostname using HAProxy? but unfortunately am not having luck.

I am trying to have it so that if a client goes to bk1.domain.com:80, traffic is sent to the "backend1" backend. Similarly, if someone goes to bk2.domain.com:80, traffic should be sent to the "backend2" backend. All other traffic should be sent to the "default" backend. For clarification, domain.com, bk1.domain.com, bk2.domain.com all resolve to the same IP address.

Unfortunately, when going to bk1.domain.com or bk2.domain.com, the "default" backend is used for all requests. It seems that HAProxy is not recognizing the host headers and as a result is unable to forward requests to the appropriate backend.

Below is the current haproxy.cfg. Any help is appreciated.

global
    log 127.0.0.1   local0
    maxconn 4096
    user haproxy
    group haproxy
    daemon

defaults
    log     global
    retries 3
    option redispatch
    maxconn 2000
    timeout http-request 5s 
    timeout connect      5s
    timeout client       30s
    timeout server       10s

frontend all_clients
    bind 0.0.0.0:80
    acl back1 hdr(host) -i bk1.domain.com
    acl back2 hdr(host) -i bk2.domian.com
    use_backend backend1 if back1
    use_backend backend2 if back2
    default_backend default

backend default
    balance roundrobin
    server  a1 192.168.0.1:8080
    server  a2 192.168.0.2:8080
    server  a3 192.168.0.3:8080

backend backend1
    balance roundrobin
    server  b1 10.0.0.1:8080
    server  b2 10.0.0.2:8080

backend backend2
    balance roundrobin
    server  c1 172.16.0.1:8080
    server  c2 172.16.0.2:8080

Answer 1

Old question, but the answer is simple: The string bk1.example.com:80 is not identical to the string bk1.example.com. Most - but not all - modern clients strip the port number from their host header before sending it, if it's the default port for the protocol.

If a client does send the port number explicitly in its host header, you need an additional ACL for that case unless you want to go the less secure route of using hdr_beg(Host).

In other words the correct syntax to catch both headers exactly might look something like this:

frontend all_clients
    bind 0.0.0.0:80
    acl back1 hdr(Host) -i bk1.domain.com
    acl back1 hdr(Host) -i bk1.domain.com:80
    acl back2 hdr(Host) -i bk2.domian.com
    acl back2 hdr(Host) -i bk2.domian.com:80
    use_backend backend1 if back1
    use_backend backend2 if back2
    default_backend default

Answer 2

snipped your code, and edited. what you need to do is define an acl, then route based on the acl:

frontend all_clients
    bind 0.0.0.0:80
    default_backend default
    acl back1 if hdr_beg(host) -i bk1.
    acl back2 if hdr_beg(host) -i bk2.
    use_backend bk1 if back1
    use_backend bk2 if back2