# PHP

> <img width="35" class="img-initial otel-icon" src="/img/logos/32x32/PHP.svg" alt="PHP"> A language-specific implementation of OpenTelemetry in PHP.

---


Welcome to the OpenTelemetry PHP documentation. This section introduces
how to use OpenTelemetry with PHP to generate and collect telemetry data
such as metrics, logs, and traces using the OpenTelemetry API and SDKs.

These pages are intended to help you get started and understand the current
capabilities and status of OpenTelemetry PHP.

## Status and Releases

The current status of the major functional components for OpenTelemetry
PHP is as follows:

| Traces              | Metrics              | Logs              |
| ------------------- | -------------------- | ----------------- |
| [Stable](/docs/specs/otel/versioning-and-stability/#stable) | [Stable](/docs/specs/otel/versioning-and-stability/#stable) | [Stable](/docs/specs/otel/versioning-and-stability/#stable) |

For releases, including the [latest release][], see [Releases][]. 

[latest release]:
  <https://github.com/open-telemetry/opentelemetry-php/releases/latest>
[Releases]:
  <https://github.com/open-telemetry/opentelemetry-php/releases>
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## Further Reading

- [OpenTelemetry for PHP on GitHub](https://github.com/open-telemetry/opentelemetry-php)
- [Examples](https://github.com/open-telemetry/opentelemetry-php/tree/main/examples)

## Requirements

OpenTelemetry SDK for PHP aims to support all officially supported PHP versions
according to
[www.php.net/supported-versions](https://www.php.net/supported-versions.php),
and support will be dropped for PHP versions within 12 months of that version
going End of Life.

Auto-instrumentation requires PHP version 8.0+.

### Dependencies

Some of the `SDK` and `Contrib` packages have a dependency on both a
[HTTP Factories (PSR-17)](https://www.php-fig.org/psr/psr-17/) and a
[php-http/async-client](https://docs.php-http.org/en/latest/clients.html)
implementation. You can find appropriate composer packages implementing given
standards on [packagist.org](https://packagist.org/).

See
[http-factory-implementations](https://packagist.org/providers/psr/http-factory-implementation)
to find a `PSR-17 (HTTP factories)` implementation, and
[async-client-implementations](https://packagist.org/providers/php-http/async-client-implementation)
to find a `php-http/async-client` implementation.

### Optional PHP extensions

| Extension                                                                 | Purpose                                                           |
| ------------------------------------------------------------------------- | ----------------------------------------------------------------- |
| [ext-grpc](https://github.com/grpc/grpc/tree/master/src/php)              | Required to use gRPC as a transport for the OTLP exporter         |
| [ext-mbstring](https://www.php.net/manual/en/book.mbstring.php)           | More performant than the fallback, `symfony/polyfill-mbstring`    |
| [ext-zlib](https://www.php.net/manual/en/book.zlib.php)                   | If you want to compress exported data                             |
| [ext-ffi](https://www.php.net/manual/en/book.ffi.php)                     | Fiber-based context storage                                       |
| [ext-protobuf](https://github.com/protocolbuffers/protobuf/tree/main/php) | _Significant_ performance improvement for otlp+protobuf exporting |

#### ext-ffi

Fibers support can be enabled by setting the `OTEL_PHP_FIBERS_ENABLED`
environment variable to `true`. Using fibers with non-`CLI` SAPIs may require
preloading of bindings. One way to achieve this is setting
[`ffi.preload`](https://www.php.net/manual/en/ffi.configuration.php#ini.ffi.preload)
to `src/Context/fiber/zend_observer_fiber.h` and setting
[`opcache.preload`](https://www.php.net/manual/en/opcache.preloading.php) to
`vendor/autoload.php`.

#### ext-protobuf

The [native protobuf library](https://packagist.org/packages/google/protobuf) is
significantly slower than the extension. We strongly encourage the use of the
extension.

## Setup

OpenTelemetry for PHP is distributed via
[packagist](https://packagist.org/packages/open-telemetry/), in a number of
packages. We recommend that you install only the packages that you need, which
as a minimum is usually `API`, `Context`, `SDK` and an exporter.

We strongly encourage that your code only depend on classes and interfaces in
the `API` package.

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Section pages:

- [Getting Started](/docs/languages/php/getting-started/): Get up and running with OpenTelemetry for PHP.
- [Instrumentation](/docs/languages/php/instrumentation/): Manual instrumentation for OpenTelemetry PHP
- [Using instrumentation libraries](/docs/languages/php/libraries/)
- [Exporters](/docs/languages/php/exporters/)
- [Context](/docs/languages/php/context/): Learn how the context API works in instrumented applications.
- [Propagation](/docs/languages/php/propagation/): Context propagation for the PHP API
- [Resources](/docs/languages/php/resources/)
- [SDK](/docs/languages/php/sdk/)
- [API reference](/docs/languages/php/api/)
- [Examples](/docs/languages/php/examples/)
- [Registry](/docs/languages/php/registry/): Instrumentation libraries, exporters and other useful components for OpenTelemetry PHP