Return the client error if there was one instead of the generic
"no healthy upstream or error"

This registers the Collectors iff the metrics plugin has been loaded.
Safes a bunch of code in each and every plugin's setup code.

* plugin/metrics: set server address in context

Allow cross server block metrics to co-exist; for this we should label
each metric with the server label. Put this information in the context
and provide a helper function to get it out.

Abstracting with entirely away with difficult as the release client_go
(0.8.0) doesn't have the CurryWith functions yet. So current use is like
so:

define metric, with server label:

	RcodeCount = prometheus.NewCounterVec(prometheus.CounterOpts{
		Namespace: plugin.Namespace,
		Subsystem: "forward",
		Name:      "response_rcode_count_total",
		Help:      "Counter of requests made per upstream.",
	}, []string{"server", "rcode", "to"})

And report ith with the helper function metrics.WithServer:

	RcodeCount.WithLabelValues(metrics.WithServer(ctx), rc, p.addr).Add(1)

Drop the doTrue and doFalse and use a pointer to a bool to do a proper
tri-bool.

Check for trunacted in the lookup function as well and use the Match
function here as well.

My routers acts funny when it sees it non RD query; make this HC as
boring as possible

* plugin/{cache,forward,proxy}: don't allow responses that are bogus

Responses that are not matching what we've been querying for should be
dropped. They are converted into FormErrs by forward and proxy; as a 2nd
backstop cache will also not cache these.

* plug

* add explicit test

* request.Scrub: test for rl==size case

Make a test case for the new break statement in Scrub and also
account for the OPT record that may get re-added in SizeAndDo() -
otherwise we may break clients that expect this.

* Fix comment

Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Underscore these names.

Recent bind refactoring missed this:

    grpc://example.com.:1055
    example.com.:1053 on 127.0.0.1

now becomes

    grpc://example.com.:1055 on 127.0.0.1
    example.com.:1053 on 127.0.0.1

If you're using *bind* directive.

Remove startup and shutdown completely

This fix adds PTR record support for Route53 plugin

This fix fixes 1595
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

This PR documents the trick exposed in coredns/coredns#1357 about using wildcards to get all POD IPs from a service with ClusterIP (as used in 'endpoints')

While looking into route53 plugin I notice the test case
was incorrect and does not really test the reply. This
fix fixes the issue in the test.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

These log print don't have any verbs, so just use plain Print

Jump through all the hoops to make this work.

* dockerfile: remove MAINTAINER

is a group effort and the field is deprecated anyways.
Fix comment to ref standard instead of impl. detail.

* link

Also add Also See Section.

Mechanical change; ran the above command.

* plugin/health: make reload work

Remove the once.Do from the startup, so we can re-bind the HTTP
listener. Also clarify the usage of health in multiple server blocks
(this is not the best approach - but there isn't a generic solution at
this point).

Manual tested as we lack testing infra, i.e kill -SIGUSR1 and some
CURLing of the health endpoint.

* Readme test fix

* update

* dont need this

* plugin/metrics: still need nil check for shutdown

the second prometheus statement will trigger: (on control-C)

[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x94f45a]

goroutine 25 [running]:
github.com/coredns/coredns/plugin/metrics.(*Metrics).OnShutdown(0xc420252000, 0x0, 0x0)
	/home/miek/g/src/github.com/coredns/coredns/plugin/metrics/metrics.go:107 +0x2a
github.com/coredns/coredns/plugin/metrics.(*Metrics).OnShutdown-fm(0x0, 0x0)
	/home/miek/g/src/github.com/coredns/coredns/plugin/metrics/setup.go:39 +0x2a
github.com/mholt/caddy.(*Instance).ShutdownCallbacks(0xc4202c81e0, 0x0, 0x0, 0x0)
	/home/miek/g/src/github.com/mholt/caddy/caddy.go:164 +0xb3
github.com/mholt/caddy.allShutdownCallbacks(0x1743935, 0x8, 0x14a1b40)
	/home/miek/g/src/github.com/mholt/caddy/sigtrap.go:95 +0x10d
github.com/mholt/caddy.executeShutdownCallbacks.func1()
	/home/miek/g/src/github.com/mholt/caddy/sigtrap.go:75 +0x8f
sync.(*Once).Do(0x2256b80, 0xc42036df88)
	/home/miek/upstream/go/src/sync/once.go:44 +0xbe
github.com/mholt/caddy.executeShutdownCallbacks(0x174033f, 0x6, 0x0)
	/home/miek/g/src/github.com/mholt/caddy/sigtrap.go:71 +0x73
github.com/mholt/caddy.trapSignalsCrossPlatform.func1.1()
	/home/miek/g/src/github.com/mholt/caddy/sigtrap.go:61 +0x36
created by github.com/mholt/caddy.trapSignalsCrossPlatform.func1
	/home/miek

* comments on why

Couldn't revert the original commit, just manually perform the needed
tweaks.

* wip

* plugin/metrics: fix reload behavior

Fixes #1472

Fixes #1564

* server: drop logging

Drop this log line; you have no control over it; it doesn't add that
much and can be used to easily ddos you.

* compile