coredns/plugin/autopath/README.md

# autopath

## Name

*autopath* - allows for server-side search path completion.

## Description

If it sees a query that matches the first element of the configured search path, *autopath* will
follow the chain of search path elements and return the first reply that is not NXDOMAIN. On any
failures, the original reply is returned. Because *autopath* returns a reply for a name that wasn't
the original question it will add a CNAME that points from the original name (with the search path
element in it) to the name of this answer.

## Syntax

~~~
autopath [ZONE...] RESOLV-CONF
~~~

* **ZONES** zones *autopath* should be authoritative for.
* **RESOLV-CONF** points to a `resolv.conf` like file or uses a special syntax to point to another
  plugin. For instance `@kubernetes`, will call out to the kubernetes plugin (for each
  query) to retrieve the search list it should use.

If a plugin implements the `AutoPather` interface then it can be used.

## Metrics

If monitoring is enabled (via the *prometheus* directive) then the following metric is exported:

* `coredns_autopath_success_count_total{server}` - counter of successfully autopath-ed queries.

The `server` label is explained in the *metrics* plugin documentation.

## Examples

~~~
autopath my-resolv.conf
~~~

Use `my-resolv.conf` as the file to get the search path from. This file only needs so have one line:
`search domain1 domain2 ...`

~~~
autopath @kubernetes
~~~

Use the search path dynamically retrieved from the *kubernetes* plugin.

## Known Issues

In Kubernetes, *autopath* is not compatible with pods running from Windows nodes.

If the server side search ultimately results in a negative answer (e.g. `NXDOMAIN`), then the client will fruitlessly search all paths manually, thus negating the *autopath* optimization.