HAProxy error detected while parsing switching rule : no such ACL : '{hdr(host)'

Working on configuring HAProxy with SSL for our lower environment. Currently, the LB is working for non-ssl but we are converting to use SSL. We have multiple sites in QA and for non-ssl I am using ACL's and its working fine.

For some reason when I restart the service I receive the following error:

Dec 9 10:56:11 haproxy haproxy: [ALERT] 343/105611 (52875) : parsing [/etc/haproxy/haproxy.cfg:27] : error detected while parsing switching rule : no such ACL : '{hdr(host)'.

Here is my current SSL Config:

global
   log /dev/log local0
   log /dev/log local1 notice
   chroot /var/lib/haproxy
   stats timeout 30s
   user haproxy
   group haproxy
   daemon

defaults
   log global
   mode http
   option httplog
   option dontlognull
   option dontlognull
   option forwardfor
   option http-server-close
   stats enable
   timeout connect 5000
   timeout client 50000
   timeout server 50000


frontend qa_b2b_https_front
   mode http
   bind *:443 ssl crt /etc/haproxy/certs.d/
   use_backend qa_b2b_http_back if {hdr(host) -i qawebsecure.oursite.com}

backend qa_b2b_http_back
   server qab2b 10.5.140.176:80 check

Solution

To define anonymous ACLs, you have to add a space before and after the opening and closing brace.

To quote the documentation on this topic:

It is also possible to form rules using "anonymous ACLs". Those are unnamed ACL expressions that are built on the fly without needing to be declared. They must be enclosed between braces, with a space before and after each brace (because the braces must be seen as independent words).

As such, your use_backend rule should look like this instead:

use_backend qa_b2b_http_back if { hdr(host) -i qawebsecure.oursite.com }