* middleware/proxy: Kill goroutines on stop

Ports caddy's https://github.com/mholt/caddy/commit/59bf71c2932c3b814a6a1211c492a1aa9f71d4a1

Excludes the proxy_test.go test part though.

Fixes #644

* Add tests

* Revert "middleware/proxy: Make Unhealthy a pointer (#615)"

This reverts commit acbf522c.

* middleware/proxy: add proper locking

This add the proper locking around `Unhealthy`.

* add listen addr option

* Add listen address option to pprof

* There is configuration

* code styling

This method parses the Host field in the service. It returns 1 or 3
things 1) it is a host 2) an IPv4 address or an 3) IPv6 address.
This simplifies some code a bit and allows for 1 way of parsing the Host
field.

This *only* parse the Host field, Mail and/or Text values should be
checked separately.

We reuse the dns.TypeXXX values for this as to not invent anything new.

Url was wrong

Print corresponding error message when TLS initialization fails.

Add a MAINTAINERS file. It's not generated and not as elaborate (i.e. no
focus areas) as the one prometheus uses. But it's a start.

Generated with `git shortlog -s -n`, everyone with more than 5 commits.

Docs are put in `Makefile.release`.

Fixes #566

* Add fallthrough support for Kubernetes

This enables registering other services in the same zone as
Kubernetes services. This also re-orders the middleware chain
so that Kubernetes comes before other types, in order to make
this work out-of-the-box.

* Remove extra line

* Implements tracing in the native gRPC server

* Undo some unnecessary changes

* Properly revert trace/setup.go this time

* Some very very basic tests

* Remove warning for non-Trace middleware

This adds a simple reload test for the UDP socket.

* middleware/erratic: allow TC bit to be set

Add `truncate` as an option.

Fixes #593

* middleware/erratic: add delying queries

* Dont println

Pointer updates are atomic so drop the sync.RWMutex as it is not needed
anymore. This also fixes the race introduced with dfc71df0 (although I
believe this is the first time we properly tested that code path).

Add test for checking the additional section after a SRV query. Though
this wasn't fixed, but it is.

Fixes #609

middleware/metrics: allow multiple listeners

There was no inherent reason *not* to allow multiple listeners for the
monitoring data. Actually enforcing only one listener lead to more code
then just allowing multiple. It's probably not what you want; but
CoreDNS is happy to oblige.

Add middleware by directly linking it from caddy, i.e. without any code
changes. To be fair: this does not added a ServeHTTP, but does give
some nice features in the Corefile.

* Fix race on backend health status update
* Ensure test case is compatible on Go 1.7

Allow HTTP health check to be performed against a regular DNS upstream server.

TODO: Add tests.

Also don't default to a default proxy; keep it empty.
Normalize the zones, so that is the server block ones are used, it will
actually work.

* add proxy tcp

* add truncated for tcp to udp response

* move truncation to scrubbing

* add test that executes upstream over tcp

* middleware/proxy: some tweaks

rename force-tcp to force_tcp to be inline with the rest and use
a dnsOptions struct to put the options in to allow it to be extended.
Add some parse tests as well.

* Fix test and rename dnsOptions Options

According to the code, the default health check interval is 30 seconds,
not 10 as stated in the documentation.  (The alternative would be to
adjust the interval in the code.)

* core: add listening for other protocols

Allow CoreDNS to listen for TLS request coming over port 853. This can
be enabled with `tls://` in the config file.

Implement listening for grps:// as well.

a Corefile like:

~~~
. tls://.:1853 {
    whoami
    tls
}
~~~

Means we listen on 1853 for tls requests, the `tls` config item allows
configuration for TLS parameters. We *might* be tempted to use Caddy's
Let's Encrypt implementation here.

* Refactor coredns/grpc into CoreDNS

This makes gRPC a first class citizen in CoreDNS. Add defines as being
just another server.

* some cleanups

* unexport the servers

* Move protobuf dir

* Hook up TLS properly

* Fix test

* listen for TLS as well. README updates

* disable test, fix package

* fix test

* Fix tests

* Fix remaining test

* Some tests

* Make the test work

* Add grpc test from #580

* fix crash

* Fix tests

* Close conn

* README cleanups

* README

* link RFC

The deps target needs to be dependent on the generated middleware code,
or you end up having to do make twice.

We don't need to use the muxer in Go DNS s we only have one entry point
per server - and mux ourselves in ServeDNS. Also make ServeDNS take a
context, and make that the canonical way to call all middleware.

* Add edns0 code rewrite

* check arg count

* change `new`; set EDNS0 if request doesn't have it set

* change set to replace_or_append

* change to append_or_replace

* return error in new

* update documents

* fixt UT

* return error

* go fmt

* Rework for more general EDNS0 use

Also changed how rules are created and validated. Implements
EDNS0 NSID in addition to local.

* go fmt

* README updates, NSID tests and fixes

* gofmt -s -w

* Fix tests for rewrite syntax change

* Add tests, fix error message

* Review nits

* Missed on nit

* More tests, integration test, fix edns0 parse issue

* Fix README, use RewriteIgnored

* go fmt

In both etcd and k8s don't error log NXDOMAIN as this log spams the logs
for no good reason.

Fixes #568

Better long term solution is log rate limiting for both *log* and
*error*.

Set of small cleanups.

This fix updates the Makefile to add the `go lint` check
for the build. This fix also fixes several go lint issues.

NOTE: This fix does not enforce `go lint` (suggestion only).
This fix also ignores the `go lint` error:
```
middleware/middleware.go:72:1: context.Context should be the first parameter of a function
```
as it requires too many changes in API.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add CNCF Code of Conduct
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

* Fix reference to CNCF

https://cncf.io