* Add a template plugin

The template plugin matches the incoming query by class, type and regex
and templates a response with go templates.

* Fix go style errors

* Fix template README example

* Fix corefile example in plugin/template

* Clarify plugin/template/README.md

Add more details and external links where needed.

* Fix code issues in plugin/template

* Add template metrics

* Add section and template to template plugin metrics

* Fix style / remove extra newline on go imports

* Fix typo in plugin/template/README.md

* Update README.md

I've change the format a bit in a PR that I merged yesterday.

* Add authority section to plugin/template

* Fix naming of incoming query name in plugin/template/README.md

* Fix doc syntax in plugin/template/README.md

* Add authority section to plugin/template/README.md config overview

* Add metric labels to plugin/template/README.md metrics section

* Use request.Request to pass state to the template matcher

* Simplify plugin/pkg/fall

* Remove unused import

* Fix fall_test

* Get fall coverage to 100% just because

* gofmt. sigh.

* Add pkg/fall for Fallthrough

Move this into it's own package to facilitate tests. Important bug
was fixed: make the names fully qualified.

Add fall package to hosts, reverse, etcd, and fix kubernetes and any
tests. The k8s tests are still as-is, might need a future cleanup.

* Add zone filtering to fallthrough

* Doh. gofmt

* Update documentation

Fixes #1331

We already do the right thing here, but add a test none-the-less.

This is probably the first in a series to fix "crazy" pod queries.
If the namespace doesn't exist return NXDOMAIN.

It might be worth extending this 1:1 to findServices as well.

* Add manual pages

Generate manual pages from the README and extend README with Name and
Description sections.

The generation requires 'ronn' which may not be available. Just check in
all generated manual pages.

We passed 2M docker pulls from DockerHub. Adds `docker pulls` badge
to README.md
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

It looks like our code coverage is above 50% now. Let's
make it a requirement to prevent it from regress.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* plugin/dnssec: implement shotgun from CloudFlare

Put a whole bunch of types in the NSEC bitmap and remove the one that's
being asked for.

Add more records for queries to the apex, SOA, DNSKEY, MX.

* Update k8s client-go to v6.0.0

This fix updates k8s client-go to v6.0.0 as CoreDNS is supported
in 1.9 and v6.0.0 is the recommended version.

There are quite some massive changes that need to be made:
1. k8s.io/client-go/pkg/api/v1 has been changed to k8s.io/api/v1 (repo changed from `client-go` to `api`)
2. kubernetes.Clientset adds one extra layer, so that `kubernetes.Clientset.Services()` and like has been changed to `kubernetes.Clientset.CoreV1().Services()`

Also, we have to stick with specific commits of `k8s.io/apimachinery` and the newly introduced `k8s.io/api`
because go dep still could not figure out the right version to fetch.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Update vendor with `dep ensure --update` and `dep prune`
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

After initial startup, see if prometheus is loaded and if so, register
our metrics with it.
Stop doing the init() func and just use the sync.Once so we don't double
registrer our metrics.

* Stop vendoring prometheus

* Fix make

This leave most of the code intact, but we need to stop vendoring
prometheus, because, again, plugins what want to use it. Not vendoring
prometheus makes my forward metrics show up again. Code looks bit
convoluted, but works:

~~~
	c.OnStartup(func() error {
		once.Do(func() {
			m := dnsserver.GetConfig(c).Handler("prometheus")
			if m == nil {
				return
			}
			if x, ok := m.(*metrics.Metrics); ok {
				x.MustRegister(RequestCount)
				x.MustRegister(RcodeCount)
				x.MustRegister(RequestDuration)
				x.MustRegister(HealthcheckFailureCount)
				x.MustRegister(SocketGauge)
			}
		})
	})
~~~

If you have no handlers for any zone CoreDNS would crash, this is very
*uncommon*, because it makes your server a bit unusable. Example config:
~~~
. {
    #forward . tls://9.9.9.9 8.8.8.8 {
    #    health_check 5s
    #    tls_servername dns.quad9.net
    #}
    pprof
    debug
}
~~~
It this does nothing and doesn't setup you plugin chain because pprof and
debug don't handle queries

* dnstest: add multirecorder

This adds a new recorder that captures all messages written to it. This
can be useful when, for instance, testing AXFR which can write muliple
messages back to the client.

* docs

Default to empty DOCKER var so you wont accidently push to the
production dockerhub. But allow to be overriden to you can push
to your registry. This allows you to re-use the CoreDNS makefiles for
your internal CI/CD.

Hacked Makefile with echos:

make DOCKER=bla -f Makefile.release docker-push
Pushing: 1.0.1
for arch in amd64 arm arm64 ppc64le s390x; do \
    echo docker push bla/coredns:coredns-$arch ;\
done
docker push bla/coredns:coredns-amd64
docker push bla/coredns:coredns-arm
docker push bla/coredns:coredns-arm64
docker push bla/coredns:coredns-ppc64le
docker push bla/coredns:coredns-s390x
echo manifest-tool push from-args --platforms linux/amd64,linux/arm,linux/arm64,linux/ppc64le,linux/s390x --template bla/coredns:coredns-ARCH --target bla/coredns:1.0.1
manifest-tool push from-args --platforms linux/amd64,linux/arm,linux/arm64,linux/ppc64le,linux/s390x --template bla/coredns:coredns-ARCH --target bla/coredns:1.0.1
echo manifest-tool push from-args --platforms linux/amd64,linux/arm,linux/arm64,linux/ppc64le,linux/s390x --template bla/coredns:coredns-ARCH --target bla/coredns:latest
manifest-tool push from-args --platforms linux/amd64,linux/arm,linux/arm64,linux/ppc64le,linux/s390x --template bla/coredns:coredns-ARCH --target bla/coredns:latest

The README.md was updated by not the actual metric.

Fixes #1321

The `apache/thrift` recently released a new version of `0.11.0`
several days ago. This release is compatible with other packages
and as such, there is no need to pinning the `apache/thrift`
to `master` anymore in Gopkg.toml.

This fix removes the pinning of `apache/thrift` in Gopkg.toml,
and updates all dependencies of coredns.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

`hanlder` -> `handler`

`bounderies` -> `boundaries`
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

This fix expose directives in dnsserver package, so that external
plugin developers could easily build customerized coredns+plugin
without changing the code base tree of coredns.

The following is an example that could bundle coredns+example,
in one simple file without modifying coredns codebase:

```
package main

import (
        _ "github.com/coredns/example"

        "github.com/coredns/coredns/coremain"
        "github.com/coredns/coredns/core/dnsserver"
)

var directives = []string{
        "example",
        "log",
        "errors",
        ...
        ...
        ...
        "whoami",
        "startup",
        "shutdown",
}

func init() {
        dnsserver.Directives = directives
}

func main() {
        coremain.Run()
}
```
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

Resolves: #1307

prometheus.Handler is deprecated according to the godoc for the package so
instead we're using promhttp.

Additionally, we are exposing the Registry that metrics is using so other
plugins that are not inside of coredns can read the registry. Otherwise, if
we kept using the Default one, there's no way to access that from outside
of the coredns repo since it is vendored.

If external plugins wanted to extend metrics there was no way since
zoneNames couldn't be initialized. Now plugins can call New to get an
instance of Metrics that they can extend.

* Moving TransferParse from file to its own package

* Adding tests for parse

Switched health and autopath plugin to allow any plugins to be used instead
of a hardcoded list. I did not switch federation over since it wasn't
obvious that anything other than kubernetes could be used with it.

Fixes #1291

When z.Tree.Prev returns zero we should break out of this loop, not
use elem as if nothing has happened.

Can be triggered by sending edns0 to unsigned zone.

DS is peculiar and needs some special cases to do the right things.
For a direct query return the DS, but if we're hitting below the
delegation return the NS+DS in a delegation response.

Don't put NS records in the answer section; if we see it is delegated
we should put the records in the AUTHORITY section.

This removes a special case, which is good.

add an example and some typos fixed.