README

A lightweight PHP library to log your LLM API calls to Langfuse for observability and analytics.

Supported Providers

Provider	Class	Models
OpenAI	`OpenAIProvider`	GPT-4, GPT-4o, o1, o3-mini, etc.
Anthropic	`AnthropicProvider`	Claude 3.5 Sonnet, Claude 3 Opus, etc.
Google	`GoogleProvider`	Gemini 1.5 Pro, Gemini 2.0, etc.
xAI	`XAIProvider`	Grok-2, Grok-2 mini, etc.

Installation

composer require uodev/langfuse-logger

Quick Start

<?php

declare(strict_types=1);

use Langfuse\LangfuseLogger;
use Langfuse\Providers\OpenAIProvider;

require 'vendor/autoload.php';

// Initialize the logger
$logger = new LangfuseLogger(
    'https://cloud.langfuse.com', // Base URL
    'pk-lf-...',                  // Public Key
    'sk-lf-...'                   // Secret Key
);

// Optional: Set user and session
$logger->setUserId('user-123')
       ->setSessionId('session-abc');

// Log your API response
$logger->log(
    new OpenAIProvider(),  // Provider instance
    'gpt-4o',              // Model name
    $messages,             // Messages array sent to API
    $response              // Response array from API
);

Provider Examples

OpenAI

use Langfuse\Providers\OpenAIProvider;

$logger->log(
    new OpenAIProvider(),
    'gpt-4o',
    $messages,
    $response
);

Anthropic (Claude)

use Langfuse\Providers\AnthropicProvider;

$logger->log(
    new AnthropicProvider(),
    'claude-3-5-sonnet-20241022',
    $messages,
    $response
);

Google (Gemini)

use Langfuse\Providers\GoogleProvider;

$logger->log(
    new GoogleProvider(),
    'gemini-1.5-pro',
    $messages,
    $response
);

xAI (Grok)

use Langfuse\Providers\XAIProvider;

$logger->log(
    new XAIProvider(),
    'grok-2',
    $messages,
    $response
);

Requirements

PHP >= 7.4
ext-curl
ext-json

Features

Multi-Provider Support: OpenAI, Anthropic, Google, xAI out of the box
Token Parsing: Automatically parses cached input tokens and reasoning tokens
Cost Tracking: Reports real input (non-cached) and cached input separately
Extensible: Implement ProviderInterface to add custom providers
Type Safe: Strict types and interfaces throughout

Configuration

Get your Langfuse credentials from Langfuse Cloud or your self-hosted instance.

Parameter	Description
`baseUrl`	Langfuse API URL (e.g., `https://cloud.langfuse.com`)
`publicKey`	Your Langfuse public key (`pk-lf-...`)
`secretKey`	Your Langfuse secret key (`sk-lf-...`)

Custom Provider

Implement the ProviderInterface to add support for other LLM providers:

<?php

declare(strict_types=1);

use Langfuse\Contracts\ProviderInterface;
use Langfuse\DTO\Usage;

class MyCustomProvider implements ProviderInterface
{
    public function parseResponse(array $response): Usage
    {
        // Extract tokens from your provider's response format
        return new Usage(
            $inputTokens,
            $outputTokens,
            $totalTokens,
            $cachedTokens,
            $reasoningTokens
        );
    }

    public function formatMessages(array $messages): string
    {
        // Format messages to string
    }

    public function extractOutput(array $response): string
    {
        // Extract output content from response
    }

    public function getName(): string
    {
        return 'my-custom-provider';
    }
}

Full Example

See the example.php file for complete working examples.

# Clone the repo
git clone https://github.com/uodev/langfuse-logger-php.git
cd langfuse-logger-php

# Install dependencies
composer install

# Configure your API keys
cp .env.example .env
# Edit .env with your keys

# Run examples
php example.php openai     # OpenAI
php example.php anthropic  # Claude
php example.php google     # Gemini
php example.php xai        # Grok

API Reference

`LangfuseLogger`

`setUserId($userId): self`

Set the user ID for tracking. Returns self for method chaining.

`setSessionId($sessionId): self`

Set the session ID for grouping related traces. Returns self for method chaining.

`log(ProviderInterface $provider, string $model, array $messages, array $response, array $metadata = []): bool`

Log an LLM API call to Langfuse.

Parameter	Type	Description
`$provider`	ProviderInterface	Provider instance (e.g., `new OpenAIProvider()`)
`$model`	string	Model name (e.g., `gpt-4o`, `claude-3-5-sonnet`)
`$messages`	array	The messages array sent to the API
`$response`	array	The decoded response from the API
`$metadata`	array	Optional additional metadata

Returns true on success, false on failure.

License

MIT License - see the LICENSE file for details.

Development

# Install dependencies
composer install

# Run tests
composer test

# Run specific test
composer test:filter UsageTest

# Run tests with coverage report
composer test:coverage

Contributing

Contributions are welcome! Please make sure tests pass before submitting a Pull Request.

uodev / langfuse-logger

Maintainers

Details