Provided by: gdnsd_2.3.0-1_amd64 bug

NAME

       gdnsd-plugin-metafo - gdnsd plugin for address meta-failover

SYNOPSIS

       Minimal example gdnsd config file using this plugin:

         plugins => {
           metafo => {
             resources => {
               prod_www => {
                 datacenters => [ dc-01, dc-02, dc-03 ]
                 dcmap => {
                   dc-01 => 192.0.2.1
                   dc-02 => { lb01 => 192.0.2.2, lb02 => 192.0.2.3 }
                   dc-03 => [ 192.0.2.4, 192.0.2.5, 192.0.2.6 ]
                 }
               },
               prod_foo => {
                 datacenters => [ dc-01, dc-02, dc-bk ]
                 dcmap => {
                   dc-01 => { lb01 => 192.0.1.1, lb02 => 192.0.1.2 }
                   dc-02 => [ 192.0.5.1, 192.0.5.2, 192.0.5.3 ]
                   dc-bk => fallback.static.cname.example.com.
                 }
               }
             }
           }
         }

       Example zonefile RRs:

         www      600 DYNA metafo!prod_www
         www-dc01 600 DYNA metafo!prod_www/dc-01
         foo      700 DYNC metafo!prod_foo

DESCRIPTION

       gdnsd-plugin-metafo is a meta-plugin.  It does static-ordered address failover between
       multiple "datacenters" (which may or may not correspond with real datacenters, it's just a
       convenient label).  Each datacenter is defined in terms of other plugins such as
       "multifo", "weighted", etc, as described below.

CONFIGURATION - TOP-LEVEL

       The top level of the metafo plugin's configuration (i.e. "plugins => { metafo => { ... }
       }") supports only one fixed, required key, "resources", whose value must be a hash.  The
       contents of "resources" is a key per named resource, with the value defining that
       resource.

       Any other keys present at the top level will be inherited down inside of each per-resource
       hash inside the "resources" stanza, acting as per-resource defaults for anything not
       defined explicitly there, as explained below.

CONFIGURATION - RESOURCES

       All keys within the resources stanza represent named resources, which can be referenced by
       "DYNA" RRs in zonefiles (e.g. "www DYNA metafo!resource_name").  Each resource's value
       must be a key-value hash configuring the resource itself.  Lightweight structural example:

         plugins => {
           metafo => {
             resources => { resA => { ... }, resB => { ... } }
           }
         }

       Within a resource, there are only two specifically meaningful keys:

       "datacenters = [ A, B, C, ... ]"
           Array of datacenter names, required.  This is the set of datacenter name labels used
           for this resource, in the order they will be checked for failover.

       "dcmap = { ... }"
           Hash, required.  The "dcmap" is a key-value hash where the keys must be exactly the
           list of datacenters defined in this resource's "datacenters" list, and the values
           defined the address configuration of each datacenter.  Another minimal structural
           example down to this level:

             plugins => {
               metafo => {
                 resources => {
                   resA => {
                     datacenters => [ dc01, dc02 ],
                     dcmap => {
                       dc01 => ???
                       dc02 => ???
                     }
                   }
                 }
               }
             }

           There are several forms the per-datacenter values ("???" above) can take, documented
           in the next section.

       Any keys other than "datacenters" and "dcmap" at the per-resource level serve as inherited
       defaults for each per-datacenter configuration inside of the "dcmap".

PER-DATACENTER RESOLUTION

       The value of the datacenters within the "dcmap" section of a resource can take several
       forms.  It is important to understand that for the most part, plugin_metafo does not deal
       with this level of results itself, but instead delegates the work at this scope to other
       plugins.  These sub-plugins, in turn, also notify metafo of complete failure at their
       level, which is the information metafo uses to know to fail over to the next datacenter in
       the list.

       The most direct and obvious way to do this is with a direct reference of the form
       "%plugin!resource", as shown here:

         plugins => {
           metafo => {
             resources => {
               resA => {
                 datacenters => [ dc1, dc2 ],
                 dcmap => {
                   dc1 => %multifo!res_mfo1
                   dc2 => %multifo!res_mfo2
                 }
               }
             }
           }
           multifo => {
             res_mfo1 => { lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
             res_mfo2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
           }
         }

       However, to make life simpler in the simple cases, plugin_metafo can synthesize the lower-
       level plugin's configuration from a hash, like so:

         plugins => {
           metafo => {
             resources => {
               resA => {
                 datacenters => [ dc1, dc2 ],
                 dcmap => {
                   dc1 => { plugin => multifo, lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
                   dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
                   # the above are effectively treated as:
                   # dc1 => %multifo!metafo_resA_dc1
                   # dc2 => %multifo!metafo_resA_dc2
                 }
               }
             }
           }
           # below does not exist in your configfile, but is what plugin_metafo
           #   synthesizes to support the above:
           #multifo => {
           #  metafo_resA_dc1 => { lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
           #  metafo_resA_dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
           #}
         }

       Within a hash like the above, the special key "plugin" will be stripped out internally and
       used to name the plugin we synthesize the config for.  "plugin" defaults to "multifo" if
       not specified.  Note that "plugin" could also be specified at the resource level (just
       inside of the "resA" stanza) to change the default for all "dcmap" entries in one
       resource, and could also be specified at the outer-most scope (just inside the "metafo"
       stanza) to change the default for all resources.

       The defaulted-down "plugin" is also the default for the direct-reference
       "%plugin!resource" form discussed earlier.  With the correct default plugin name, it can
       be shortened to just "!resource".

       The same sort of key-value inheritance scheme (top-level -> per-resource level -> per-
       datacenter level) can also be used for any other parameter in synthesized resource
       configurations specific to the per-datacenter plugin(s) you are using.  A common example
       would be the "service_types" parameter that most plugins which support monitored address
       results have.  Note that these other values (e.g. service_types) would only apply to
       synthesized resources, not to direct-references like "%multifo!foo", which must be
       configured entirely separately within that plugin's config.

       There are three other possible shortcut values for datacenters: a single direct address,
       an array of addresses, or a single CNAME hostname.  If a single IP address or an array of
       IP addresses are specified, plugin_metafo will synthesize a hash from them with the plugin
       forced to "multifo" (since it cannot know the syntax of hashes for all other plugins,
       which may differ), and give them address labels 1, 2, etc.

       If the value for a datacenter is a single CNAME hostname, no sub-plugin is used, and that
       CNAME result is returned directly.  Note that any resource with such an entry can only be
       used with "DYNC" RRs, and not "DYNA" RRs (as is the case if any subplugin's configuration
       is capable of returning CNAME data).

       A much more complete example, showing off most of the features above:

         plugins => {
           metafo => {
             plugin => multifo # change default for all resources
             service_types => [ bar ] # default service_types for synthesized below
             resources => {
               resA => {
                 plugin => multifo # change default for this resource
                 service_types => [foo, bar] # services types for synthesized below:
                 datacenters => [ dc1, dc2, dc3, dc4, dc5, dc6, dc7, dc8 ],
                 dcmap => {
                   dc1 => { plugin => multifo, lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
                   dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
                   dc3 => %simplefo!foo
                   dc4 => { plugin => simplefo, primary => 192.0.2.100, secondary => 192.0.2.101 }
                   dc5 => !bar
                   dc6 => 192.0.2.150
                   dc7 => [ 192.0.2.180, 192.0.2.181 ]
                   dc8 => last.resort.example.com.
                 }
               }
             }
           }
           # below, commented-out sections show configuration synthesized
           #   by plugin_metafo, whereas the rest are direct-references that
           #   had to be manually specified here:
           multifo => {
             # metafo_resA_dc1 => { lb01 => 192.0.2.1, lb02 => 192.0.2.3, service_types => [foo, bar] }
             # metafo_resA_dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113, service_types => [foo, bar] }
             bar => { asd => 192.0.2.77, xyz => 192.0.2.88 }
             # metafo_resA_dc6 => { 1 => 192.0.2.150, service_types => [foo, bar] }
             # metafo_resA_dc7 => { 1 => 192.0.2.180, 2 => 192.0.2.181, service_types => [foo, bar] }
           }
           simplefo => {
             foo => { primary => 192.0.2.80, secondary => 192.0.2.81 }
             # metafo_resA_dc4 => { primary => 192.0.2.100, secondary => 192.0.2.101, service_types => [foo, bar] }
           }
         }

       Note in the example above that "%multifo!bar" and "%simplefo!foo" would have had their
       default "service_types = up" rather than the one specified at the metafo level, because
       they were not synthesized.  It would be up to you to keep all of the service_types in sync
       when using direct references.

SYNTHETIC PER-DATACENTER RESOURCES

       This plugin will synthesize additional, per-datacenter resource names from your
       configuration.  They are named as "resname/dcname".  For example, if you define a metafo
       resource named "prodwww" with the datacenter list "[ pri, sec ]", the resource names
       "prodwww/pri" and "prodwww/sec" will be sythesized and can be used in zonefile records,
       e.g.:

         www-backup 300 DYNA metafo!prodwww/sec

       When used, these per-datacenter synthetic resource names cause a given lookup to skip the
       normal failover process and directly return results from that particular datacenter.

SEE ALSO

       gdnsd.config(5), gdnsd.zonefile(5), gdnsd(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/>.