resolvers section lists DNS nameservers that HAProxy Enterprise will query when it needs to resolve a hostname to an IP address. Each
resolvers keyword is followed by a label, such as mynameservers, to differentiate it from others.
resolvers mynameservers nameserver ns1 192.168.2.10:53 nameserver ns2 192.168.3.10:53
nameserver line indicates the IP address and port of a DNS nameserver. HAProxy Enterprise queries all of the nameservers and uses the first, valid response that it receives.
Resolvers configuration examples
The most common way to use this feature is to configure backend server hostnames instead of IP addresses. When defining a list of servers in a
listen section, you can use DNS names.
In the following configuration sample the servers defined in backend webservers are using the
resolvers field on each
server line to reference the
resolvers section that will be used to resolve the server's name.
resolvers mynameservers nameserver ns1 192.168.2.10:53 nameserver ns2 192.168.3.10:53 backend webservers server s1 hostname1.example.com:80 check resolvers mynameservers server s2 hostname2.example.com:8080 check resolvers mynameservers server s3 hostname3.example.com:8080 check resolvers mynameservers
Adjusting DNS settings
You can adjust how HAProxy Enterprise queries nameservers and caches the responses. The following sample configuration contains a resolvers section with all available options configured.
resolvers mynameservers nameserver ns1 192.168.2.10:53 nameserver ns2 192.168.3.10:53 # Maximum size of a DNS answer allowed, in bytes accepted_payload_size 512 # How long to cache answers depending on the name resolution status hold valid 10s hold other 30s hold refused 30s hold nx 30s hold timeout 30s hold obsolete 30s # How many times to retry a query resolve_retries 3 # How long to wait between retries when no valid response has been received timeout retry 1s # How long to wait for a successful resolution timeout resolve 1s