SignalFx Tracing Library for PHP

This library provides an OpenTracing-compatible tracer and automatically configurable instrumentations for many popular PHP libraries and frameworks. It is a native extension that supports PHP versions 5.4+ running on the Zend Engine.

The SignalFx Tracing Library for PHP is in beta.

Supported Libraries and Frameworks

These are the PHP libraries and frameworks you can instrument. All italicized libraries are in beta.

If your web framework isn't supported, the instrumentation creates a span for any fielded request using the $_SERVER execution environment.

Library	Versions supported
CakePHP	2.x
Curl	All supported PHP versions
ElasticSearch	1.x
Eloquent	All supported Laravel versions
Guzzle	5.0+
Laravel	4.2, 5.0+
Lumen	5.2+
Memcached	All supported PHP versions
MongoDB	1.4
MySQLi	All supported PHP versions
PDO	All supported PHP versions
Predis	1.1
Slim	3.x
Symfony	3.3, 3.4, 4.x
Zend	1.12

Configuration values

Configure the tracer and instrumentation with these environment variables:

Environment variable	Description	Default value
SIGNALFX_SERVICE_NAME	The name to identify the service in SignalFx.	'unnamed-php-service'
SIGNALFX_ENDPOINT_URL	The endpoint the tracer sends spans to. Send spans to a Smart Agent.	'http://localhost:9080/v1/trace'
SIGNALFX_TRACING_ENABLED	Whether to enable automatic tracer creation and instrumentation.	true
SIGNALFX_TRACING_CLI_ENABLED	Whether to enable automatic tracer creation and instrumentation for cli SAPI.	false
SIGNALFX_TRACE_DEBUG	Whether to enable debug-level logging.	false
SIGNALFX_DISTRIBUTED_TRACING	Whether to enable B3 context propagation for applicable client and server libraries.	true
SIGNALFX_RECORDED_VALUE_MAX_LENGTH	Maximum length an attribute value can have. Values longer than this are truncated.	1200

Because auto-instrumentation is applied during initialization, all configuration environment variables MUST be set by launch time. Anything set via putenv() may not be considered in configuration loading.

Configure the SignalFx Tracing Library for PHP

Download the tracing library and install the PHP extension with your system's package manager. After you install the PHP extension, your application sends trace data to the endpoint URL you specify.

1. Download the latest release of the SignalFx Tracing Library for PHP.
2. Install with PHP extension with your system's package manager:

   # Using dpkg:
   $ dpkg -i signalfx-tracing.deb
   
   # Using rpm:
   $ rpm -ivh signalfx-tracing.rpm
   
   # Using apk:
   $ apk add signalfx-tracing.apk --allow-untrusted
   
   # Directly from the release bundle:
   $ tar -xf signalfx-tracing.tar.gz -C / && /opt/signalfx-php-tracing/bin/post-install.sh

Use OpenTracing for custom instrumentation

The signalfx_tracing extension provides and configures an OpenTracing-compatible tracer you can use for custom instrumentation:

use SignalFx\GlobalTracer; // Suggested namespace over OpenTracing for GlobalTracer
use OpenTracing\Tags;

function myApplicationLogic($indicator) {
  $tracer = GlobalTracer::get(); //  Will provide the tracer instance used by provided instrumentations
  $span = $tracer->startActiveSpan('myApplicationLogic')->getSpan();
  $span->setTag('indicator', $indicator);

  try {
    $widget = myAdditionalApplicationLogic($indicator);
    $span->setTag('widget', $widget);
    return $widget;
  } catch (Exception $e) {
    $span->setTag(Tags\ERROR, true);
    throw $e;
  } finally {
    $span->finish();
  }
}

The OpenTracing-compatible tracer provides a beta implementation of the Scope Manager. If you aren't using the beta 1.0.x opentracing/opentracing release, the registered tracer provided by SignalFx\GlobalTracer::get() supports the 0.3.x version API as well. As there have been breaking changes to the OpenTracing\GlobalTracer, use the SignalFx\GlobalTracer proxy's get() method for accessing the tracer instance.

Tracing CLI sessions

If you want to trace cli SAPI functionality, you have to manually enable it. When you enable cli tracing, the instrumentation automatically creates a root span to denote the lifetime of your cli session. This SAPI is disabled by default to avoid undesired traced system activity.

$ export SIGNALFX_TRACING_CLI_ENABLED=true
$ php artisan migrate:fresh
$ php myTracedCliScript.php

Advanced Usage

The Signalfx-Tracing library for PHP wraps the spl_autoload_register function to allow the automatic tracing of supported functions without user action. In cases where autoloader classes aren't used, a manual invocation to create a tracer and invoke auto-instrumentation is required as the first action for your application:

// Note: this must occur before any other library is imported and used!
use SignalFx\Tracing;

$tracer = Tracing::autoInstrument();
// or if you only prefer a tracer instance without enabling auto-instrumentation:
$tracer = Tracing::createTracer();

About

This library is a fork of the DataDog Tracing PHP Client that has been modifed to provide Zipkin v2 JSON formatting, B3 trace propagation functionality, and properly annotated trace data for handling by SignalFx Microservices APM. It is released under the terms of the BSD 3-Clause license. See the license file for more details.