Recursor - Coredns Io

+++ title = "recursor" description = "recursor resolves domains using defined IP addresses or resolving other mapped domains using defined resolvers" weight = 10 tags = [ "plugin" , "recursor" ] categories = [ "plugin", "external" ] date = "2023-01-30T16:15:00+02:00" repo = "https://github.com/kinjelom/coredns-recursor" home = "https://github.com/kinjelom/coredns-recursor/blob/main/README.md" +++

Description

The recursor resolves domains using defined IP addresses or resolving other mapped domains using defined resolvers.

Syntax

txt

recursor {   
    [external-yaml config-file-path]
    [external-json config-file-path]

    [verbose 0..2]
    zone: zone.name
    [resolver non-default {
        urls udp://ip-1:port udp://ip-n:port
        [timeout_ms 500]
    }]
    [alias alias-name | * {
        [hosts domain-1 domain-n]
        [ips ip-1 ip-n]
        [resolver_name non-default]
        [ttl custom-ttl]
    }]
}

The recursor definition:

zone - DNS zone for the recursor
verbose - stdout logs level:
- 0 - minimal
- 1 - middle
- 2 - talkative
resolvers - other DNS servers:
- map-key/id: name of resolver, default overrides system default resolver
- urls: list of URL addresses, example: udp://127.0.0.1:53 (system default is represented by ://default)
- timeout_ms: resolver connection timeout in millisecods
aliases - domain aliases:
- map-key/id: name of alias, subdomain or * if you want the recursor to be a DNS repeater
- ips: IP addresses to return as a part of answer
- hosts: domains to be resolved so that the IP addresses obtained in this way will be returned as a part of answer
- resolver_name: the defined resolver reference, default is... default of course :)
- ttl: DNS record Time To Live in seconds

Metrics

If monitoring is enabled (via the prometheus directive) the following metric is exported.

Health

This plugin implements dynamic health checking. It will always return healthy though.

Examples

Corefile

txt

recursor {   
    [external-yaml config-file-path]
    [external-json config-file-path]

    [verbose 0..2]
    zone: demo.svc
    resolver dns-c {
        urls udp://1.1.1.1:53 udp://1.0.0.1:53
        timeout_ms 500
    }
    resolver dns-g {
        urls udp://8.8.8.8:53 udp://8.8.4.4:53
    }  
    resolver demo {
        urls udp://10.0.0.1:53
    }  
    alias alias1 {
        hosts www.example.org www.example.com
        resolver_name dns-c
        ttl 11
    }
    alias alias2 {
        ips 10.0.0.1 10.0.0.2
        ttl 12
    }
    alias alias3 {
        ips 10.0.0.1 10.0.0.2
        hosts www.example.net
        resolver_name dns-g
        ttl 13
    }
    alias alias4 {
        hosts www.example.net
        ttl 14
    }  

    alias * {
        resolver_name demo
        ttl 15
    }  
}

External YAML

yaml

zone: demo.svc
resolvers:
  dns-c:
    urls: [ udp://1.1.1.1:53, udp://1.0.0.1:53 ]
    timeout_ms: 500
  dns-g:
    urls: [ udp://8.8.8.8:53, udp://8.8.4.4:53 ]
  demo:
    urls: [ udp://10.0.0.1:53 ]
aliases:
  alias1:
    hosts: [ www.example.org, www.example.com ]
    resolver_name: dns-c
    ttl: 11
  alias2:
    ips: [ 10.0.0.1, 10.0.0.2 ]
    ttl: 12
  alias3:
    ips: [ 10.0.0.1, 10.0.0.2 ]
    hosts: [ www.example.net ]
    resolver_name: dns-g
    ttl: 13
  alias4:
    hosts: [ www.example.net ]
    ttl: 14
  "*":
    resolver_name: demo
    ttl: 15

External JSON

json

{
  "zone": "demo.svc",
  "resolvers": {
    "dns-c": {
      "urls": [ "udp://1.1.1.1:53", "udp://1.0.0.1:53" ],
      "timeout_ms": 500
    },
    "dns-g": {
      "urls": [ "udp://8.8.8.8:53", "udp://8.8.4.4:53" ]
    },
    "demo": {
      "urls": [ "udp://10.0.0.1:53" ]
    }
  },
  "aliases": {
    "alias1": {
      "hosts": [ "www.example.org", "www.example.com" ],
      "resolver_name": "dns-c",
      "ttl": 11
    },
    "alias2": {
      "ips": [ "10.0.0.1", "10.0.0.2" ],
      "ttl": 12
    },
    "alias3": {
      "ips": [ "10.0.0.1", "10.0.0.2" ],
      "hosts": [ "www.example.net" ],
      "resolver_name": "dns-g",
      "ttl": 13
    },
    "alias4": {
      "hosts": [ "www.example.net" ],
      "ttl": 14
    },
    "*": {
      "resolver_name": "demo",
      "ttl": 15
    }
  }
}

Also See

See the manual.