coredns/plugin/trace/README.md

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 is supported and that is what it defaults to.
• 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

. {
    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

Trace one query every 10000 queries, rename the service, and enable same span:

trace tracinghost:9411 {
	every 10000
	service dnsproxy
	client_server
}