Jaeger Bindings for PHP OpenTracing API

This is a client-side library that implements an OpenTracing Tracer, with Zipkin-compatible data model. The library's package is qualtrics/jaeger-client-php.

IMPORTANT: Please note that while jaeger-client-php can record and report spans, it is still under active development and remains incomplete in a number of ways. It's modeled after jaeger-client-go in design, but many components are not yet implemented and the API is still subject to change.

Required Reading

In order to understand the library, one must first be familiar with the OpenTracing project and specification more specifically. Additionally, one should review the PHP OpenTracing API.

How to Contribute

We're still working on this; reach out to @tylerchr for now.

Installation

We recommend using a dependency manager like Composer when including this library into an application. For example, add these lines to your composer.json file:

{
    ...
    "require": {
        ...
        "qualtrics/jaeger-client-php": "dev-master"
    }
}

Initialization

use Jaeger\Reporter\RemoteReporter;
use Jaeger\Sampler\ProbabilisticSampler;
use Jaeger\Tracer;
use Jaeger\Transport\JaegerTransport;
use OpenTracing\GlobalTracer;

GlobalTracer::set(Tracer::create("service-name", [
    Tracer::SAMPLER => new ProbabilisticSampler(0.01), // Sample 1% of requests.
    Tracer::REPORTER => new RemoteReporter(new JaegerTransport("127.0.0.1", "5775")), // Send to jaeger-agent on localhost:5775
]));

You'll likely also want to make sure to flush the tracer just prior to application shutdown. The simplest way to do this is by registering a custom shutdown function:

register_shutdown_function(function() {

    GlobalTracer::get()->flush();

})

Instrumentation for Tracing

Since this tracer is fully compliant with the OpenTracing API 1.0, all code instrumentation should only use the API itself, as descriped in the opentracing-php documentation.

Features

Reporters

A "reporter" is a component receives the finished spans and reports them to somewhere. Under normal circumstances, the Tracer should use the default RemoteReporter, which sends the spans out of process via configurable "transport". Additionally, the NullReporter, a no-op reporter that does nothing, may be helpful to e.g. ignore trace data when tracing is disabled.

Transports

The remote reporter uses "transports" to actually send the spans out of process. Currently the only supported transport is Thrift over UDP. Perhaps more transports will be added in the future.

Two data formats are currently supported:

• The native Jaeger Thrift span format, which is accepted by the emitBatch API of jaeger-agent
• The Zipkin Thrift 1.x span format, which allows easy integration of the tracer with Zipkin backends and is also accepted by the emitZipkinBatch API of jaeger-agent

Sampling

The tracer does not record all spans, but only those that have the sampling bit set in the flags. When a new trace is started and a new unique ID is generated, a sampling decision is made concerning whether this trace should be sampled. The sampling decision is propagated to all downstream calls via the flags field of the trace context. The following samplers are available:

• ConstSampler always makes the same sampling decision for all trace IDs. it can be configured to either sample all traces, or to sample none.
• ProbabilisticSampler uses a fixed sampling rate as a probability for a given trace to be sampled. The actual decision is made by comparing the trace ID with a random number multiplied by the sampling rate.

Baggage Injection

Baggage is not currently supported.

License

Apache 2.0 License.