coredns/middleware/httpproxy/README.md
Miek Gieben 4cfd19c7c9 middleware/httpproxy: add debug queries (#446)
* middleware/httproxy: implement debug queries

Not too useful at the moment, but o-o.debug queries are supported
and return the Comment from dns.google.com.

Note that this is not always set.

* improve documentation

* Testing cleanups
2016-11-29 09:54:57 +00:00

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# httpproxy
*httpproxy* proxies DNS request to a proxy using HTTPS (or HTTP/2 - not implemented). Usually this
involves sending a JSON payload over this transport and translating the response back to DNS. The
current supported backend is Google, using the URL: https://dns.google.com .
## Syntax
In its most basic form, a simple http proxy uses this syntax:
~~~
httpproxy FROM TO
~~~
* **FROM** is the base domain to match for the request to be proxied.
* **TO** is the destination endpoint to proxy to, accepted values here are `dns.google.com`.
For changing the defaults you can use the expanded syntax:
~~~
proxy FROM TO {
upstream ADDRESS...
}
~~~
* `upstream` defines upstream resolvers to be used (re-)resolve `dns.google.com` (or other names in the
future) every 30 seconds. When not specified the combo 8.8.8.8, 8.8.4.4 is used.
## Metrics
If monitoring is enabled (via the *prometheus* directive) then the following metric is exported:
* coredns_httpproxy_request_count_total{zone, proto, family}
## Examples
Proxy all requests within example.org to Google's dns.google.com.
~~~
proxy example.org dns.google.com
~~~
Proxy everything, and re-lookup `dns.google.com` every 30 seconds using the resolvers specified
in /etc/resolv.conf.
~~~
proxy . dns.google.com {
upstream /etc/resolv.conf
}
~~~
## Debug queries
Debug queries are enabled by default and currently there is no way to turn them off. When CoreDNS
receives a debug queries (i.e. the name is prefixed with `o-o.debug.` a TXT record with Comment from
`dns.google.com` is added. Note this is not always set, but sometimes you'll see:
`dig @localhost -p 1053 mx o-o.debug.example.org`:
~~~ txt
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;o-o.debug.example.org. IN MX
;; AUTHORITY SECTION:
example.org. 1799 IN SOA sns.dns.icann.org. noc.dns.icann.org. 2016110711 7200 3600 1209600 3600
;; ADDITIONAL SECTION:
. 0 CH TXT "Response from 199.43.133.53"
~~~