README.md

Zipkin Instrumentation for Symfony HTTP Client

This bundle provides an implementation of Symfony's HTTP Client component that enables tracing.

Using the HTTP Client

You can wrap an existing HTTP Client:

use Symfony\Component\HttpClient\HttpClient;
use ZipkinBundle\Components\HttpClient as ZipkinHttpClient;

$client = new ZipkinHttpClient(HttpClient::create(), $tracing);
$response = $client->request('GET', 'https://api.github.com/repos/symfony/symfony-docs');

Or declare it as a service:

services:
  zipkin.http_client:
    class: ZipkinBundle\Components\HttpClient\HttpClient
    arguments:
      - "@http_client"
      - "@zipkin.default_http_client_tracing"

Note: You can also include the src/ZipkinBundle/Components/HttpClient/Resources/config/services.yml in the services declaration.

Be aware that ZipkinBundle\Components\HttpClient\HttpClient is just a wrapper around an existing HTTP Client, hence if you want to configure its settings by passing options you can do that with the underlaying client or setting the options in the default one.

Once declared the zipkin http client as a service you can inject it using the Symfony DI or using the autowiring alias. See this documentation for more details.

Customizing spans

Zipkin client instrumentation provides a Zipkin\Instrumentation\Http\Client\HttpClientParser interface which is used for customizing the tags being added to a span based on the request and the response data, the default parser Zipkin\Instrumentation\Http\Client\DefaultHttpClientParser provides the usual tags and span name but you can use your own to get more accurate information.

services:
  search.http_client_tracing:
    class: Zipkin\Instrumentation\Http\Client\HttpClientTracing
    arguments:
      - "@zipkin.default_tracing"
      - "@search_http_parser" # my own parser

  search.http_client:
    class: ZipkinBundle\Components\HttpClient\HttpClient
    arguments:
      - "@http_client"
      - "@search.http_client_tracing"

  search_http_parser:
    class: My\Search\HttpClientParser

and the parser would look like:

namespace My\Search;

use Zipkin\Instrumentation\Http\Client\DefaultHttpClientParser;
use Zipkin\Instrumentation\Http\Client\Response;
use Zipkin\Instrumentation\Http\Client\Request;
use Zipkin\Propagation\TraceContext;
use Zipkin\SpanCustomizer;

final class HttpClientParser extends DefaultHttpClientParser {
    public function request(Request $request, TraceContext $context, SpanCustomizer $span): void {
        parent::request($request, $context, $span);
        if (null !== ($searchKey = $request->getHeader('search_key'))) {
            $span->tag('search_key', $searchKey);
        }
    }
}