coredns/plugin/trace/README.md
2018-03-09 15:08:57 -05:00

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# trace
## Name
*trace* - enables OpenTracing-based tracing of DNS requests as they go through the plugin chain.
## Description
With *trace* you enable OpenTracing of how a request flows through CoreDNS.
## Syntax
The simplest form is just:
~~~
trace [ENDPOINT-TYPE] [ENDPOINT]
~~~
* **ENDPOINT-TYPE** is the type of tracing destination. Currently only `zipkin` and `datadog` are supported.
Defaults to `zipkin`.
* **ENDPOINT** is the tracing destination, and defaults to `localhost:9411`. For Zipkin, if
ENDPOINT does not begin with `http`, then it will be transformed to `http://ENDPOINT/api/v1/spans`.
With this form, all queries will be traced.
Additional features can be enabled with this syntax:
~~~
trace [ENDPOINT-TYPE] [ENDPOINT] {
every AMOUNT
service NAME
client_server
}
~~~
* `every` **AMOUNT** will only trace one query of each AMOUNT queries. For example, to trace 1 in every
100 queries, use AMOUNT of 100. The default is 1.
* `service` **NAME** allows you to specify the service name reported to the tracing server.
Default is `coredns`.
* `client_server` will enable the `ClientServerSameSpan` OpenTracing feature.
## Zipkin
You can run Zipkin on a Docker host like this:
```
docker run -d -p 9411:9411 openzipkin/zipkin
```
## Examples
Use an alternative Zipkin address:
~~~
trace tracinghost:9253
~~~
or
~~~ corefile
. {
trace zipkin tracinghost:9253
}
~~~
If for some reason you are using an API reverse proxy or something and need to remap
the standard Zipkin URL you can do something like:
~~~
trace http://tracinghost:9411/zipkin/api/v1/spans
~~~
Using DataDog:
~~~
trace datadog localhost:8125
~~~
Trace one query every 10000 queries, rename the service, and enable same span:
~~~
trace tracinghost:9411 {
every 10000
service dnsproxy
client_server
}
~~~