Zipkin is a distributed tracing system. It is an open source system that is developed
by Twitter to trace real-time data. Zipkin is used to aggregate real-time monitoring
data that is collected from multiple heterogeneous systems. In Tracing Analysis, you
can use Zipkin to report PHP application data.
Add instrumentation to the code
To use Zipkin to report PHP application data to the Tracing Analysis console, you
must first add instrumentation to the code.
- Install Zipkin PHP.
composer require openzipkin/zipkin
- Create a Tracer object. The Tracer object can be used to create spans that record
the time of distributed operations. The Tracer object contains information such as
the endpoint for data reporting, IP address of the on-premises server, and sampling
rate. You can adjust the sampling rate to reduce the overheads that are generated
in data reporting.
function create_tracing($endpointName, $ipv4)
{
$endpoint = Endpoint::create($endpointName, $ipv4, null, 2555);
/* Do not copy this logger into production.
* Read https://github.com/Seldaek/monolog/blob/master/doc/01-usage.md#log-levels
*/
$logger = new \Monolog\Logger('log');
$logger->pushHandler(new \Monolog\Handler\ErrorLogHandler());
$reporter = new Zipkin\Reporters\Http(\Zipkin\Reporters\Http\CurlFactory::create());
$sampler = BinarySampler::createAsAlwaysSample();
$tracing = TracingBuilder::create()
->havingLocalEndpoint($endpoint)
->havingSampler($sampler)
->havingReporter($reporter)
->build();
return $tracing;
}
- Record the request data.
$rootSpan = $tracer->newTrace();
$rootSpan->setName('encode')
$rootSpan->start();
try {
doSomethingExpensive();
} finally {
$rootSpan->finish();
}
Note
You can run the preceding code to create a root span that records the root operation
of a request. If you need to record the previous and next operations of a request,
inject a context. Sample code:
$span = $tracer->newChild($parentSpan->getContext());
$span->setName('encode');
$span->start();
try {
doSomethingExpensive();
} finally {
$span->finish();
}
- Optional:Add custom tags to a span for quick troubleshooting. For example, you can add a custom
tag to check whether an error occurs or to record the return value of a request.
$span->tag('http.status_code', $resultCode);
- Optional:The root operation determines the sampling rate of requests. In general, a sampling
policy is created together with the Tracer object. However, you can apply custom sampling
policies to specific operations. Sample code:
private function newTrace(Request $request) {
$flags = SamplingFlags::createAsEmpty();
if (strpos($request->getUri(), '/experimental') === 0) {
$flags = DefaultSamplingFlags::createAsSampled();
} else if (strpos($request->getUri(), '/static') === 0) {
$flags = DefaultSamplingFlags::createAsSampled();
}
return $tracer->newTrace($flags);
}
- In a distributed system, remote procedure call (RPC) requests are sent along with
trace data. Trace data contains the values of the TraceId, ParentSpanId, SpanId, and
Sampled parameters. You can call the Extract or Inject method to pass data in HTTP
request headers. The following figure shows the overall process.
Client Span Server Span
┌──────────────────┐ ┌──────────────────┐
│ │ │ │
│ TraceContext │ Http Request Headers │ TraceContext │
│ ┌──────────────┐ │ ┌───────────────────┐ │ ┌──────────────┐ │
│ │ TraceId │ │ │ X-B3-TraceId │ │ │ TraceId │ │
│ │ │ │ │ │ │ │ │ │
│ │ ParentSpanId │ │ Inject │ X-B3-ParentSpanId │Extract │ │ ParentSpanId │ │
│ │ ├─┼─────────>│ ├────────┼>│ │ │
│ │ SpanId │ │ │ X-B3-SpanId │ │ │ SpanId │ │
│ │ │ │ │ │ │ │ │ │
│ │ Sampled │ │ │ X-B3-Sampled │ │ │ Sampled │ │
│ └──────────────┘ │ └───────────────────┘ │ └──────────────┘ │
│ │ │ │
└──────────────────┘ └──────────────────┘
- Call the Inject method on the client to inject the context information.
// configure a function that injects a trace context into a request
$injector = $tracing->getPropagation()->getInjector(new RequestHeaders);
// before a request is sent, add the current span's context to it
$injector->inject($span->getContext(), $request);
- Call the Extract method to extract the context information.
// configure a function that extracts the trace context from a request
$extracted = $tracing->getPropagation()->extractor(new RequestHeaders);
$span = $tracer->newChild($extracted)
$span->setKind(Kind\SERVER);
Quick start
The following official Zipkin PHP example shows you how to use Zipkin to report PHP
application data.
- Download the Demo file.
- Change the endpoint for data reporting in the functions.php file. Replace
$reporter = new Zipkin\Reporters\Http(\Zipkin\Reporters\Http\CurlFactory::create());
with the following code:
Notice Replace
<endpoint>
with the corresponding endpoint in the corresponding region that is displayed on
the
Overview page. For more information about how to obtain access point information, see
Obtain access point information.
reporter = new Zipkin\Reporters\Http(\Zipkin\Reporters\Http\CurlFactory::create(),
['endpoint_url' => '<endpoint>
',]);
- Install dependencies.
// As of zipkin php is still in 1.0.0-betaX
rm composer.lock && composer install
- Start services.
# Run the composer run-frontend command on Terminal 1.
# Run the composer run-backend command on Terminal 2.
- Visit the frontend page to report data. You can view the reported data in the Tracing Analysis console.
curl http://localhost:8081
FAQ
Q: Why is no data reported after I follow the steps in Quick start?
A: Check whether the endpoint is valid.