Files
coredns/plugin/secondary
Miek Gieben 5f41d8eb1f reverse zone: fix Normalize (#4621)
Make normalize return multiple "hosts" (= reverse zones) when a
non-octet boundary cidr is given.

Added pkg/cidr package that holds the cidr calculation routines; felt
they didn't really fit dnsutil.

This change means the IPNet return parameter isn't needed, the hosts are
all correct. The tests that tests this is also removed: TestSplitHostPortReverse
The fallout was that zoneAddr _also_ doesn't need the IPNet member, that
in turn make it visible that zoneAddr in address.go duplicated a bunch
of stuff from register.go; removed/refactored that too.

Created a plugin.OriginsFromArgsOrServerBlock to help plugins do the
right things, by consuming ZONE arguments; this now expands reverse
zones correctly. This is mostly mechanical.

Remove the reverse test in plugin/kubernetes which is a copy-paste from
a core test (which has since been fixed).

Remove MustNormalize as it has no plugin users.

This change is not backwards compatible to plugins that have a ZONE
argument that they parse in the setup util.

All in-tree plugins have been updated.

Signed-off-by: Miek Gieben <miek@miek.nl>
2021-05-17 13:19:54 -07:00
..
2018-07-19 16:23:06 +01:00
2021-04-05 09:34:25 -04:00
2021-05-17 13:19:54 -07:00

secondary

Name

secondary - enables serving a zone retrieved from a primary server.

Description

With secondary you can transfer (via AXFR) a zone from another server. The retrieved zone is not committed to disk (a violation of the RFC). This means restarting CoreDNS will cause it to retrieve all secondary zones.

Syntax

secondary [ZONES...]
  • ZONES zones it should be authoritative for. If empty, the zones from the configuration block are used. Note that without a remote address to get the zone from, the above is not that useful.

A working syntax would be:

secondary [zones...] {
    transfer from ADDRESS [ADDRESS...]
}
  • transfer from specifies from which ADDRESS to fetch the zone. It can be specified multiple times; if one does not work, another will be tried. Transferring this zone outwards again can be done by enabling the transfer plugin.

When a zone is due to be refreshed (refresh timer fires) a random jitter of 5 seconds is applied, before fetching. In the case of retry this will be 2 seconds. If there are any errors during the transfer in, the transfer fails; this will be logged.

Examples

Transfer example.org from 10.0.1.1, and if that fails try 10.1.2.1.

example.org {
    secondary {
        transfer from 10.0.1.1 10.1.2.1
    }
}

Or re-export the retrieved zone to other secondaries.

example.net {
    secondary {
        transfer from 10.1.2.1
    }
    transfer {
        to *
    }
}

Bugs

Only AXFR is supported and the retrieved zone is not committed to disk.

See Also

See the transfer plugin to enable zone transfers to other servers.