NAME

       gdnsd-plugin-simplefo - gdnsd plugin for simple primary->secondary address failover

SYNOPSIS

       Example gdnsd config fragment using this plugin:

         plugins => {
           simplefo => {
             service_types => [ www ],
             pubwww => {
               primary => 192.0.2.1
               secondary => 192.0.2.100
             }
             www6 => {
               primary => 2001:DB8::1
               secondary => 2001:DB8::100
             }
             mixed => {
               service_types => [ www, xmpp ]
               addrs_v4 => {
                 primary => 192.0.2.1
                 secondary => 192.0.2.100
               }
               addrs_v6 => {
                 service_types => up
                 primary => 2001:DB8::1
                 secondary => 2001:DB8::100
               }
             }
           }
         }

       Example zonefile RRs:

         www 180 DYNA simplefo!pubwww
         www6 180 DYNA simplefo!www6
         mix 180 DYNA simplefo!mixed

DESCRIPTION

       gdnsd-plugin-simplefo is designed to do simple active/passive failover between one primary
       address and one secondary address.  The status of the addresses are checked with standard
       gdnsd "service_types" monitoring.  If you need more than a simple two-address failover
       list, the "metafo" plugin is more appropriate.

TOP-LEVEL PLUGIN CONFIG

       At the top level of the plugin's configuration stanza, the special parameter
       "service_types" is supported. These sets the default per-resource "service_types" for all
       resources.  The default default "service_types" is "[ default ]", which does basic
       HTTP/1.0 polling for 200 OK status from "http://IPADDR:80/".

       The rest of the hash entries at the top level are the names of the resources you define.
       Each resource gets a configuration hash of its own for containing resource-specific
       address info.

RESOURCE CONFIG

       Within a resource, "service_types" is again supported, to set the monitored service
       type(s) for this specific resource.

       If "addrs_v4" is defined, it must be a hash containing two keys: "primary" and
       "secondary", each of which has an IPv4 string address value.

       Similarly, if "addrs_v6" is defined, it must be a hash containing two keys: "primary" and
       "secondary", each of which has an IPv6 string address value.

       If neither of those two sub-stanzas is defined, you must define a single pair of "primary"
       and "secondary" addresses for the whole resource.  These can be of either address family,
       so long as they are both the same family.

       When "addrs_v4" and/or "addrs_v6" are used, "service_types" can also be overridden within
       each, for different behavior per-address-family (e.g.  force one protocol always up/down).

OPERATIONAL MECHANICS

       For each address family for which you have supplied data, the following logic is applied
       independently:

       •   First, the worst monitored state of all "service_types" checks for the primary address
           is obtained.  If this state is "UP" or "DANGER", the primary address is used.

       •   If the primary address was "DOWN", the secondary address is checked: If the secondary
           is "UP" or "DANGER", it will be used.  If the secondary is also "DOWN", then the
           primary is used.

       •   In any case other than the primary being exactly "UP", the response RR-set TTL from
           the zonefile will be cut in half for both address families.

       If both "primary" and "secondary" were "DOWN" for either address family, this plugin will
       signal total resource failure to any upstream module (geoip or metafo).  The cutting of
       the TTL only happens once for all address RRs, even if both families had a non-"UP"
       primary.

SEE ALSO

       gdnsd.config(5), gdnsd.zonefile(5), gdnsd(8), gdnsd-plugin-multifo(8)

       The gdnsd manual.

COPYRIGHT AND LICENSE

       Copyright (c) 2012 Brandon L Black <blblack@gmail.com>

       This file is part of gdnsd.

       gdnsd is free software: you can redistribute it and/or modify it under the terms of the
       GNU General Public License as published by the Free Software Foundation, either version 3
       of the License, or (at your option) any later version.

       gdnsd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
       even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
       GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with gdnsd.  If
       not, see <http://www.gnu.org/licenses/>.