mirror of https://github.com/coredns/coredns.git synced 2025-10-27 08:14:18 -04:00

Files

Miek Gieben 85457cf50d plugin/secondary: fix a bunch of things and tests (#1406 )

Fix the error handling. Log when we have an error during any of the
transfer state. And if there isn't an error transfer the zones.

Also fix the tests in test/ so we, at least, check the initial transfer.

Update the docs to show more about how errors are handled.

Ref #1400

2018-01-23 10:35:10 +00:00

README.md

plugin/secondary: fix a bunch of things and tests (#1406 )

2018-01-23 10:35:10 +00:00

secondary.go

Remove the word middleware (#1067 )

2017-09-14 09:36:06 +01:00

setup_test.go

Remove the word middleware (#1067 )

2017-09-14 09:36:06 +01:00

setup.go

Moving TransferParse from file to its own package (#1286 )

2017-12-13 11:18:08 -05:00

README.md

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.

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
    transfer to ADDRESS
    upstream 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.
transfer to can be enabled to allow this secondary zone to be transferred again.
upstream defines upstream resolvers to be used resolve external names found (think CNAMEs) pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for normal authoritative serving you don't need or want to use this. ADDRESS can be an IP address, and IP:port or a string pointing to a file that is structured as /etc/resolv.conf.

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 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
        transfer from 10.1.2.1
    }
}

Or re-export the retrieved zone to other secondaries.

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

Bugs

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