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 "[ up ]", which simply sets them all
"UP" statically.
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", the
primary address is used.
- •
- If the primary address was "DOWN", the secondary address is
checked: If the secondary is "UP", 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/>.