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

This fix is an enhancement of external plugin enabling.
Previously, it was already able to build a customerized
coredns with plugins enabled selectively, without changing
coredns source code. However, all default plugins are
actually bundled because of the import rule:
```
"github.com/coredns/coredns/coremain"
```

The issue is best described with the following:
```
root@localhost:/go/src/github.com/coredns/coredns/sample# cat sample.go
package main

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

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

var directives = []string{
        "forward",
        "startup",
        "shutdown",
}

func init() {
        dnsserver.Directives = directives
}

func main() {
        coremain.Run()
}
root@localhost:/go/src/github.com/coredns/coredns/sample#
root@localhost:/go/src/github.com/coredns/coredns/sample# go build -v sample.go
root@localhost:/go/src/github.com/coredns/coredns/sample# ./sample -plugins
root@localhost:/go/src/github.com/coredns/coredns/sample# ./sample -plugins
Server types:
  dns

Caddyfile loaders:
  flag
  default

Other plugins:
  dns.auto
  dns.autopath
  dns.bind
  dns.cache
  dns.chaos
  dns.debug
  dns.dnssec
  dns.dnstap
  dns.erratic
  dns.errors
  dns.etcd
  dns.federation
  dns.file
  dns.forward
  dns.health
  dns.hosts
  dns.kubernetes
  dns.loadbalance
  dns.log
  dns.nsid
  dns.pprof
  dns.prometheus
  dns.proxy
  dns.reverse
  dns.rewrite
  dns.root
  dns.route53
  dns.secondary
  dns.template
....
```

This fix moves zplugins.go to a different package/directory so that
it is possible to "only import plugins as needed".

The following is the new output after this fix:
```
root@localhost:/go/src/github.com/coredns/coredns/sample# ./sample -plugins
Server types:
  dns

Caddyfile loaders:
  flag
  default

Other plugins:
  dns.forward
  dns.prometheus
  shutdown
  startup

root@localhost:/go/src/github.com/coredns/coredns/sample#
```
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Update vendor
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add route53 plugin

This fix adds route53 plugin so that it is possible to
query route53 record through CoreDNS.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

SOA records are returned in the authority section, not as answer.

The original ServergRPC.Listen() method returns a tls.Listener
when tls protocol is specified. Unfortunate, tls.Listener
does not implement the caddy.Listener interface that is
needed for graceful restart to work.

The change is to have the ServergRPC.Listen() method returns the
inner net.Listener instead. The creation of the tls.Listener
is deferred to the ServergRPC.Serve() method.

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

Minor textual cleanup.

The cache plugin always returned a minimum TTL of 5 seconds, regardless
of the actual TTL of the records. A cache is not authoritative for the
record TTL and should not extend it.

Minor textual cleanup.

More minor textual fixes.

Fixing a couple of small textual problems.

Just some textual cleanup:  A few misspellings and a few clarifications.

The changes in this fix have:
1. checkout master branch of dependencies (non-branch will trigger an error with go get -u)
2. go get -u
3. checkout specific versioon (not necessary a branch).
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

This fix fixes version fetched from `go get` so
that versions are guarded.

github.com/mholt/caddy              v0.10.10
github.com/miekg/dns                v1.0.3
github.com/prometheus/client_golang v0.8.0
golang.org/x/net                    release-branch.go1.9 (branch)
golang.org/x/text                   e19ae1496984b1c655b8044a65c0300a3c878dd3

This fix fixes 1368.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Constent atx headers

* Regen manual pages

* plugin/health: add 'overloaded metrics'

Query our on health endpoint and record (and export as a metric) the
time it takes. The Get has a 5s timeout, that, when reached, will set
the metric duration to 5s. The actually call "I'm I overloaded" is left
to an external entity.

* README

* golint and govet

* and the tests

These can be just vars. Think that was intended as well.

Small README updates, and fallthrough fixes (using less code)

* Align plugin/template usage and syntax with other plugins

* Use new fallthrough logic in plugin/template

* Use zone name normalization for plugin/template

* Test fallthrough parsing in plugin/template

* Rework scoping of match checks

Most matches are not plugin global but per template. The plugin does only a
very rough check while detailed checks are done per-template.

Per template checks include:
- Zones
- Class/Type
- Regex
- Fallthrough

* Remove trailing `.` from fully qualified domain names

* Register template metrics with zone/class/type instead of regex

* Remove trailing fqdn dot from multiple testcases

* plugin/proxy: max the number of upstreams

Put a max of 15 on the number of upstreams.

* plugin/template: README tweaks

* Go gen it

* 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.