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middleware/proxy: absorb httpproxy (#481)

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* middleware/proxy: absorb httpproxy

Move the httproxy into proxy. This adds and Exchanger interface which
is used to exchange the messages with the upstream.

The https_google upstream will re-resolve itself and update the upstream
hosts used every 300s.

* Remove and add TODO
This commit is contained in:
Miek Gieben
2017-02-06 19:32:48 +00:00
committed by GitHub
parent 77f957d443
commit 123a76c91e
21 changed files with 466 additions and 827 deletions
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61
middleware/proxy/README.md
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@@ -13,8 +13,8 @@ In its most basic form, a simple reverse proxy uses this syntax:
proxy FROM TO
~~~
* **FROM** is the base domain to match for the request to be proxied
* **TO** is the destination endpoint to proxy to
* **FROM** is the base domain to match for the request to be proxied.
* **TO** is the destination endpoint to proxy to.
However, advanced features including load balancing can be utilized with an expanded syntax:
@@ -26,7 +26,7 @@ proxy FROM TO... {
health_check PATH:PORT [DURATION]
except IGNORED_NAMES...
spray
protocol [dns|https_google]
protocol [dns|https_google [bootstrap ADDRESS...]]
}
~~~
@@ -39,7 +39,8 @@ proxy FROM TO... {
* `ignored_names...` is a space-separated list of paths to exclude from proxying. Requests that match any of these paths will be passed through.
* `spray` when all backends are unhealthy, randomly pick one to send the traffic to. (This is a failsafe.)
* `protocol` specifies what protocol to use to speak to an upstream, `dns` (the default) is plain old DNS, and
`https_google` uses `https://dns.google.com` and speaks a JSON DNS dialect.
`https_google` uses `https://dns.google.com` and speaks a JSON DNS dialect. Note when using this
**TO** must be `dns.google.com`.
## Policies
@@ -53,17 +54,43 @@ available. This is to preeempt the case where the healthchecking (as a mechanism
## Upstream Protocols
Currently supported are `dns` (i.e., standard DNS over UDP) and `https_google`. Note that with
`https_google` the entire transport is encrypted. Only *you* and *Google* can see your DNS activity.
Currently `protocol` supports `dns` (i.e., standard DNS over UDP/TCP) and `https_google` (JSON
payload over HTTPS). Note that with `https_google` the entire transport is encrypted. Only *you* and
*Google* can see your DNS activity.
* `dns`: no options can be given at the moment.
* `https_google`: bootstrap **ADDRESS...** is used to (re-)resolve `dns.google.com` to an address to
connect to. This happens every 300s. If not specified the default is used: 8.8.8.8:53/8.8.4.4:53.
Note that **TO** is *ignored* when `https_google` is used, as its upstream is defined as
`dns.google.com`.
Debug queries are enabled by default and currently there is no way to turn them off. When CoreDNS
receives a debug query (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"
~~~
## Metrics
If monitoring is enabled (via the *prometheus* directive) then the following metric is exported:
* coredns_proxy_request_duration_milliseconds{zone}
* coredns_proxy_request_count_total{proto, from}
The metric shows the duration for a proxied request, the `zone` label is the **FROM** as specified
in the configuration.
Where `proto` is the protocol used (`dns`, or `https_google`) and `from` is **FROM** specified in
the config.
## Examples
@@ -111,3 +138,19 @@ proxy . /etc/resolv.conf {
except miek.nl example.org
}
~~~
Proxy all requests within example.org to Google's dns.google.com.
~~~
proxy example.org 1.2.3.4:53 {
protocol https_google
}
~~~
Proxy everything, and re-lookup `dns.google.com` every 300 seconds using 8.8.8.8:53.
~~~
proxy . 1.2.3.4:53 {
protocol https_google bootstrap 8.8.8.8:53
}
~~~