The primary driver for autopath was kubernetes.  It addresses a specific need in kubernetes, so it deserves a mention in the K8s README, with an example.

* mw/k8s: cleanups

Remove some constants that aren't used any more. Make PrimaryZone
private because it doesn't need to be exported. Remove test that
did not cover corner case as expressed in setup.go

* cleanup this as well

Found a few typos, spelling, and grammar errors.

remove extraneous "]"s from the syntax def...

* mw/k8s: Test Federation parsing

The test case was there, but there was nothing testing it?!?!?!
Add it and split it out of the main setup test which is too long
already.

Also allow kubernetes a not have a ZONE, just default to the serverblock
in that case. Remove test that was blocking that.

Cleanup up the readme more.

* rewrite README

Remove k.defaultNSMsg() it is just one line of getting the service and
it is another method that needlessly uses recordRequest.

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

* Support multiple k8s api servers specification and load balance among api servers

This fix adds supports for multiple k8s api servers specification,
load balance among api servers.

When two or more api servers are specified in kubernetes block (endpoint ...),
a proxy is created locally (with randomly generately port). The coredns
will points to the generated proxy so that load balancing could be achieved.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Setup initial healthcheck at the beginning
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Update README.md for kubernetes middleware and remove whitespaces.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Use middleware/pkg/healthcheck in middleware/kubernetes

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

* mw/k8s: remove dependence on global var

Remove the global coreDNSRecord that was used. Remove tests the
referenced that var. Cleanup the rest.

* Rename function as well

* fixes

Remove the examples, save one in the syntax section. The example
section covers all.

This brings the kubernetes README inline with other READMEs.

* mw/kubernetes: handle dns.TypeNS better.

* mw/kubernetes: cleanup typeNS replies a bit.

* core: replace GetMiddleware

See the discussion in #881. GetMiddleware would add a `nil` middleware
to the callstack thereby breaking functionality.

This PR drops it in favor of RegisterHandler which is a completely
standalone registry for middleware that want to let it self know to
other middleware.

Currenly *autopath* uses this to call *kubernetes*'s AutoPath method
for dynamic autopathing.

* Drop GetMiddleware

* Register metrics

* drop the panic

Only use was in k8s middleware; no tests other than subzone_test.go
existed; not exercised: remove.

* middleware/autopath: some fixes

This fix a small issue in autopath, but unearthed a bigger one.
See #881.

* Fix test

* middleware/authpath: Fix return from k8s mw

Return the correct search path from the kubernetes' AutoPath function.
Based on preliminary discussion in #870

* PodWithIP can be private

Fix and add docs to functions.

* CR: remove the error from AutoPathFunc

Add some docs about normalize.Host and normalize.Name. They are used
correctly in the middleware even though they are somewhat confusing,
esp when you copy from ServerBlockKeys in your middleware.

* mw/kubernetes: fix parseTests

Make parse tests table driven to remove a duplicate code, i.e. most
of the contents of parse_test.go can be removed as well as the
expectString helper function.

* cleanup parse tests

* middleware/kubernetes: pull TXT out of parseRequest

Put the TXT handling one layer higher and remove it from parseRequest.
Also rename the podsvc field in there to podOrSvc. Now that it isn't
used anymore for TXT record (dns-version) that was put in there. We can
make this a boolean (in a future PR).

Make parseRequest get an optional Zone that is from state.Zone and use
that instead of its own code. Removed some tests and other smaller
cleanups.

Fixes #836

* add this reverse

* another check

* readd

* Rename to kPod and kService for some clarity

Some `go vet` cleanup
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

The current badge styles have 4 flat and 1 regular, which were
rather inconsistent. This fix changes to one style and matches
with Caddy.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

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

* Move healthcheck to middleware/pkg/healthcheck
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

So that pull request build failure does not impact project status.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

Move reverse function and (some) test code to reverse*.go

Pull in the contents of routeRequest as it is only called once.

Call out to kubernetes to get the search path - this still needs
to return something sensible, but all infrastructure has landed
to make it work.

autopath as middleware

Add log statement pointing to replacement.
remove cidr from README and use replacement syntax.

Fixes #851

*ugh*: forgot to add these files. This add the dnsutil.TrimZone
function.

Add a Zone field in request.Request and a dnsutil.Trimzone help
function.

Factor out as much of autopath into a subpackage as possible right now.
apw.Sent is not needed, we should see this from the rcode returned by
the middleware. See #852 on why this was needed.

Disable the tests for now as to not break the main build.

* Core: convert IP addresses to reverse zone

If we see IP/mask syntax and the mask mod 8 == 0 we assume a reverse
zone and convert to in-addr or .arpa.

* typos

* integration test

* Addr is not used

* core: clean up normalize

Create a SplitHostPort function that can be used both from normalize.go
and address.go. This removes some (not all!) duplication between the
both and makes it work with reverse address notations.

* More tests

Make ClientWrite available for middleware to use.

Put the autopath stuff in a separate sub package. Tests are still
included in the main kubernetes directory.

Next steps (after this is merged), is pulling the autopath handling
into the subpackage and fixing the tests.

Add the DNS message response flags as {rflags} to the default logging
Also complete the replacer testing that is was commented out.
And (unrelated) Switch erratic and whoami to ease testing.

Note: {flags} could and should be added as well - but we can leave that
as a beginners bug.

* kubernetes/reverse: remove deadcode
* deadcode in errors and kubernetes removed
* unnecessary conversion
* constants
* proxy: time.Since()
* simplications
* static check
* Disable test/external_test

randomize the times when doing transfers and checks.

Fixes #840

dedent code, use shorter names.
use strings.EqualFold instead ToLower to avoid create garbage.