NAME

OpenTracing - support for https://opentracing.io application tracing

DESCRIPTION

The OpenTracing standard provides a way to profile and monitor applications across different components and services.

It's defined by the following specification:

https://github.com/opentracing/specification/blob/master/specification.md

and has several "semantic conventions" which provide a common way to include details for common components such as databases, caches and web applications.

This module currently implements version 1.1 of the official specification.

How to use this

There are 3 parts to this:

add tracing to your code
set up an opentracing service
have the top-level application(s) send traces to that service

Tracing

Collecting trace data is similar to a logging module such as Log::Any. Add this line to any module where you want to include tracing information:

use OpenTracing::Any qw($tracer);

This will give you an OpenTracing::Tracer instance in the $tracer package variable. You can then use this to create spans:

my $span = $tracer->span(
 name => 'example'
);

You could also use OpenTracing::DSL for an alternative way to trace blocks of code:

use OpenTracing::DSL qw(:v1);

trace {
 print 'operation starts here';
 sleep 2;
 print 'end of operation';
} name => 'example';

Integration

For some common modules and services there are integrations which automatically create spans for operations. If you load OpenTracing::Integration::DBI, for example, all database queries will be traced as if you'd wrapped every prepare/execute method with tracing code.

Most of those third-party integrations are in separate distributions, search for OpenTracing::Integration:: on CPAN for available options.

Tracers

Once you have tracing in your code, you'll need a service to collect and present the traces.

At the time of writing, there is an incomplete list here:

https://opentracing.io/docs/supported-tracers/

Application

The top-level code (applications, dæmons, cron jobs, microservices, etc.) will need to register a tracer implementation and configure it with the service details, so that the collected data has somewhere to go.

One such tracer implementation is Net::Async::OpenTracing, designed to work with code that uses the IO::Async event loop.

use IO::Async::Loop;
use Net::Async::OpenTracing;
my $loop = IO::Async::Loop->new;
$loop->add(
 my $target = Net::Async::OpenTracing->new(
  host     => 'localhost',
  port     => 6828,
  protocol => 'zipkin',
 )
);
OpenTracing->global_tracer->register($target);

See the module documentation for more details on the options.

If you're feeling lucky, you might also want to add this to your top-level application code:

use OpenTracing::Integration qw(:all);

This will go through the list of all modules currently loaded and attempt to enable any matching integrations - see "Integration" and OpenTracing::Integration for more details.

More information

See the following classes for more information:

METHODS

global_tracer

Returns the default tracer instance.

my $span = OpenTracing->global_tracer->span(name => 'test');

This is the same instance used by OpenTracing::Any and OpenTracing::DSL.

set_global_tracer

Replaces the current global tracer with the given one.

OpenTracing->set_global_tracer($tracer);

Note that a typical application would only need a single instance, and the default should normally be good enough.

If you want to set up where the traces should go, see "register" in OpenTracing::Tracer instead.

AUTHOR

Tom Molesworth TEAM@cpan.org

vanHoesel/OpenTracing