coredns/plugin/erratic/README.md
Miek Gieben c778b3a67c
plugin/health: remove ability to poll other plugins (#2547)
* plugin/health: remove ability to poll other plugins

This mechanism defeats the purpose any plugin (mostly) caching can still
be alive, we can probably forward queries still. Don't poll plugins,
just tell the world we're up and running.

It was only actually used in kubernetes; and there specifically would
mean any network hiccup would NACK the entire server health.

Fixes: #2534

Signed-off-by: Miek Gieben <miek@miek.nl>

* update docs based on feedback

Signed-off-by: Miek Gieben <miek@miek.nl>
2019-03-07 22:13:47 +00:00

93 lines
1.8 KiB
Markdown

# erratic
## Name
*erratic* - a plugin useful for testing client behavior.
## Description
*erratic* returns a static response to all queries, but the responses can be delayed, dropped or truncated.
The *erratic* plugin will respond to every A or AAAA query. For any other type it will return
a SERVFAIL response. The reply for A will return 192.0.2.53 (see [RFC
5737](https://tools.ietf.org/html/rfc5737),
for AAAA it returns 2001:DB8::53 (see [RFC 3849](https://tools.ietf.org/html/rfc3849)) and for an
AXFR request it will respond with a small zone transfer.
*erratic* can also be used in conjunction with the *autopath* plugin. This is mostly to aid in
testing.
## Syntax
~~~ txt
erratic {
drop [AMOUNT]
truncate [AMOUNT]
delay [AMOUNT [DURATION]]
}
~~~
* `drop`: drop 1 per **AMOUNT** of queries, the default is 2.
* `truncate`: truncate 1 per **AMOUNT** of queries, the default is 2.
* `delay`: delay 1 per **AMOUNT** of queries for **DURATION**, the default for **AMOUNT** is 2 and
the default for **DURATION** is 100ms.
In case of a zone transfer and truncate the final SOA record *isn't* added to the response.
## Ready
This plugin reports readiness to the ready plugin.
## Examples
~~~ corefile
. {
erratic {
drop 3
}
}
~~~
Or even shorter if the defaults suits you. Note this only drops queries, it does not delay them.
~~~ corefile
. {
erratic
}
~~~
Delay 1 in 3 queries for 50ms
~~~ corefile
. {
erratic {
delay 3 50ms
}
}
~~~
Delay 1 in 3 and truncate 1 in 5.
~~~ corefile
. {
erratic {
delay 3 5ms
truncate 5
}
}
~~~
Drop every second query.
~~~ corefile
. {
erratic {
drop 2
truncate 2
}
}
~~~
## Also See
[RFC 3849](https://tools.ietf.org/html/rfc3849) and
[RFC 5737](https://tools.ietf.org/html/rfc5737).