Introduction

Instrumentation consist of allowing the OpenTelemetry SDK to automatically generate telemetry data for your Symfony application.

A Symfony application can use several components provided by Symfony such as the console, the cache etc.

Each component require a specific instrumentation to be able to generate telemetry data. Some of them require decoration to be instrumented, others require to listen to Symfony events or extra configuration.

Note: The instrumentation is still in alpha, only generate traces and may not cover all the use cases. Please open a new issue or a pull request if you find an uncovered use case.

Here is how each component is "hooked" to allow instrumentation:

• Cache: Cache services are instrumented by decorating services tagged with cache.taggable and cache.pool tags.
• Console: Commands are instrumented by registering an event subscriber on ConsoleEvents events.
• Doctrine: A middleware is registered to wrap DBAL methods such as prepare, query, beginTransaction, commit, rollBack etc.
• Http Client: The client services are instrumented by decorated services tagged with http_client.transport or http_client tags.
• Http Kernel: Controllers are instrumented by registering an event subscriber on KernelEvents events.
• Mailer: The mailer services are instrumented by decorating services tagged with mailer.mailer tag.
  • The transport is also instrumented by decorating services tagged with mailer.transports and mailer.default_transports tag.
• Messenger: A message bus can be instrumented by configuring a new middleware called open_telemetry_tracer.
  • The transport can also be instrumented by wrapping the DSN string with trace().
• Twig: Rendering is instrumented by registering a Twig extension that adds a ProfilerNodeVisitor to the Twig environment.

Each component comes with a configuration block that allows to enable or disable the instrumentation and configure it.

open_telemetry:
  instrumentation:
    <component_name>:
      tracing:
        enabled: true
        tracer: 'open_telemetry.traces.tracers.main'

It is important to understand that the current implementation rely on entrypoint components, which create root spans to allow "secondary" components to attach their spans to it. A secondary component that does not have a root span will create orphan traces and mess with your obsa, as they won't be attached to any root span.

In a Symfony application the entrypoint components are the HttpKernel, the Console and Messenger.

• The HttpKernel is the entrypoint for requests.
• The Console is the entrypoint for commands.
• The Messenger is the entrypoint for messages.

Those entrypoint components can be configured in two ways:

• Automatically: The bundle will automatically instrument all registered routes and commands.
• Manually: Only instrument routes and commands using the #[Traceable] attribute.

For further information on tracing instrumentation, please refer to the Traces documentation.