coredns/middleware/auto

auto

auto enables serving zone data from an RFC 1035-style master file which is automatically picked up from disk.

The auto middleware is used for an "old-style" DNS server. It serves from a preloaded file that exists on disk. If the zone file contains signatures (i.e. is signed, i.e. DNSSEC) correct DNSSEC answers are returned. Only NSEC is supported! If you use this setup you are responsible for resigning the zonefile. New zones or changed zone are automatically picked up from disk.

Syntax

auto [ZONES...] {
    directory DIR [REGEXP ORIGIN_TEMPLATE [TIMEOUT]]
    no_reload
    upstream ADDRESS...
}

ZONES zones it should be authoritative for. If empty, the zones from the configuration block are used.

• directory loads zones from the speficied DIR. If a file name matches REGEXP it will be used to extract the origin. ORIGIN_TEMPLATE will be used as a template for the origin. Strings like {<number>} are replaced with the respective matches in the file name, i.e. {1} is the first match, {2} is the second, etc.. The default is: db\.(.*) {1} e.g. from a file with the name db.example.com, the extracted origin will be example.com. TIMEOUT specifies how often CoreDNS should scan the directory, the default is every 60 seconds. This value is in seconds. The minimum value is 1 second.
• no_reload by default CoreDNS will reload a zone from disk whenever it detects a change to the file. This option disables that behavior.
• upstream defines upstream resolvers to be used resolve external names found (think CNAMEs) pointing to external names.

All directives from the file middleware are supported. Note that auto will load all zones found, even though the directive might only receive queries for a specific zone. I.e:

auto example.org {
    directory /etc/coredns/zones
}

Will happily pick up a zone for example.COM, except it will never be queried, because the auto directive only is authoritative for example.ORG.

Examples

Load org domains from /etc/coredns/zones/org and allow transfers to the internet, but send notifies to 10.240.1.1

auto org {
    directory /etc/coredns/zones/org
    transfer to *
    transfer to 10.240.1.1
}

Load org domains from /etc/coredns/zones/org and looks for file names as www.db.example.org, where example.org is the origin. Scan every 45 seconds.

auto org {
    directory /etc/coredns/zones/org www\.db\.(.*) {1} 45
}