corefile.5.md

Name

corefile - configuration file for CoreDNS

Description

A corefile specifies the (internal) servers CoreDNS should run and what plugins each of these should chain. The syntax is as follows:

[SCHEME://]ZONE [[SCHEME://]ZONE]...[:PORT] {
    [PLUGIN]...
}

The ZONE defines for which name this server should be called, multiple zones are allowed and should be white space separated. You can use a "reverse" syntax to specify a reverse zone (i.e. ip6.arpa and in-addr.arpa), by using an IP address in the CIDR notation.

The optional SCHEME defaults to dns://, but can also be tls:// (DNS over TLS), grpc:// (DNS over gRPC) or https:// (DNS over HTTP/2).

The optional PORT controls on which port the server will bind, this default to 53. If you use a port number here, you can't override it with -dns.port (coredns(1)).

Specifying a ZONE and PORT combination multiple times for different servers will lead to an error on startup.

When a query comes in, it is matched again all zones for all servers, the server with the longest match on the query name will receive the query.

PLUGIN defines the plugin(s) we want to load into this server. This is optional as well, but as server with no plugins will just return SERVFAIL for all queries. Each plugin can have a number of properties than can have arguments, see the documentation for each plugin.

Comments are allowed and begin with an unquoted hash # and continue to the end of the line. Comments may be started anywhere on a line.

Environment variables are supported and either the Unix or Windows form may be used: {$ENV_VAR_1} or {%ENV_VAR_2%}.

You can use the import "plugin" to include parts of other files.

If CoreDNS can’t find a Corefile to load it loads the following builtin one:

. {
    whoami
}

Import

You can use the import "plugin" to include parts of other files, see https://coredns.io/plugins/import.

Snippets

If you want to reuse a snippet you can define one with and then use it with import.

(mysnippet) {
    log
    whoami
}

. {
    import mysnippet
}

Examples

The ZONE is root zone ., the PLUGIN is chaos. The chaos plugin takes an argument: CoreDNS-001. This text is returned on a CH class query: dig CH txt version.bind @localhost.

. {
   chaos CoreDNS-001
}

When defining a new zone, you either create a new server, or add it to an existing one. Here we define one server that handles two zones; that potentially chain different plugins:

example.org {
    whoami
}
org {
    whoami
}

Is identical to:

example.org org {
    whoami
}

Reverse zones can be specified as domain names:

0.0.10.in-addr.arpa {
    whoami
}

or by just using the CIDR notation:

10.0.0.0/24 {
    whoami
}

This also works on a non octet boundary:

10.0.0.0/27 {
    whoami
}

Authors

CoreDNS Authors.

Copyright

Apache License 2.0

See Also

The manual page for CoreDNS: coredns(1) and more documentation on https://coredns.io. Also see the import's documentation.