Revenium Middleware for Google AI (Node.js)

Automatically track and meter your Google AI API usage with Revenium. This middleware provides seamless integration with Google AI (Gemini), requiring minimal code changes.

Features

• Complete Metering: Track tokens, costs, and performance metrics
• Prompt Capture: Optional capture of prompts and responses with automatic credential sanitization
• Custom Metadata: Add business context to your AI usage
• Streaming Support: Real-time streaming with analytics
• Vector Embeddings: Full embedding support for semantic search
• Type Safe: Full TypeScript support with comprehensive types
• Analytics: Detailed usage analytics and reporting

Getting Started

Quick Start

npm install @revenium/google-genai

For complete setup instructions and usage examples, see the examples linked throughout this guide.

Step-by-Step Guide

The following guide walks you through setting up Revenium middleware in your project:

Step 1: Install the Package

npm install @revenium/google-genai

Step 2: Get Your API Keys

Revenium API Key:

1. Go to Revenium Dashboard
2. Sign up or log in
3. Navigate to API Keys section
4. Copy your API key (starts with hak_)

Google AI API Key:

1. Go to Google AI Studio
2. Sign in with your Google account
3. Click "Create API Key"
4. Copy your API key

Step 3: Setup Environment Variables

Create a .env file in your project root:

# Create .env file
echo. > .env  # On Windows (CMD TERMINAL)
touch .env  # On Mac/Linux (CMD TERMINAL)
# OR
#PowerShell
New-Item -Path .env -ItemType File

Note: A template .env.example file is included in this package at node_modules/@revenium/google-genai/examples/.env.example with all required variables and helpful comments.

Copy and paste the following into .env:

# Google AI Configuration
GOOGLE_API_KEY=your_google_ai_api_key_here

# Revenium Configuration
REVENIUM_METERING_API_KEY=your_revenium_api_key_here

# Optional: For development/testing (defaults to https://api.revenium.ai)
# REVENIUM_METERING_BASE_URL=https://api.revenium.ai

# Optional: Enable debug logging
REVENIUM_LOG_LEVEL=INFO

Step 4: Implement in Your Code

Create test-google.js with basic usage:

import { GoogleGenAIController } from "@revenium/google-genai";

const controller = new GoogleGenAIController();
const result = await controller.createChat(
  ["What is artificial intelligence?"],
  "gemini-2.0-flash-001",
);

For a complete working example, see: Google AI Basic Example

Use the examples as reference for implementing the middleware in your project. See the examples linked above for complete implementation including:

• How to initialize the controller
• Making API calls with automatic metering
• Handling streaming responses
• Adding custom metadata to track business context

Step 5: Update package.json (Optional)

Add test scripts and module type to your package.json:

{
  "name": "my-google-ai-project",
  "version": "1.0.0",
  "type": "module",
  "scripts": {
    "test-google": "node test-google.js"
  },
  "dependencies": {
    "@revenium/google-genai": "^0.1.1"
  }
}

Important: If you get a "Cannot use import statement outside a module" error, make sure your package.json includes "type": "module" as shown above.

Next Steps

For more advanced usage including streaming, embeddings, and custom metadata, see the complete examples:

• Google AI Basic Example
• Google AI Streaming Example
• Google AI Embedding Example

Running Examples from Cloned Repository

If you've cloned this repository from GitHub and want to run the included examples to see how the middleware works (without modifying the middleware source code):

Setup

# Clone the repository
git clone https://github.com/revenium/revenium-middleware-google-node.git
cd revenium-middleware-google-node

# Install dependencies
npm install

# Build the packages
npm run build

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

Run Examples

Using npm scripts:

# Google AI examples
npm run example:genai:basic      # Basic chat completion
npm run example:genai:streaming  # Streaming response
npm run example:genai:embedding  # Text embeddings

Or use npx tsx directly:

npx tsx packages/google-genai/examples/basic.ts
npx tsx packages/google-genai/examples/streaming.ts
npx tsx packages/google-genai/examples/embedding.ts

For detailed information about each example, see the examples directory.

Want to Modify the Middleware Code?

If you're planning to modify the examples or experiment with the code, the setup above is sufficient. However, if you want to modify the middleware source code itself (files in packages/google-genai/src/), you'll need to understand the development workflow.

See Local Development and Contributing below for the complete development guide.

Already have a project? Just install and replace imports:

Step 1. Install the Package

npm install @revenium/google-genai

Step 2. Add Environment Variables

Add to your existing .env file:

GOOGLE_API_KEY=your_google_ai_api_key_here
REVENIUM_METERING_API_KEY=your_revenium_api_key_here

# Optional: For development/testing (defaults to https://api.revenium.ai)
# REVENIUM_METERING_BASE_URL=https://api.revenium.ai

# Optional: Enable debug logging
REVENIUM_LOG_LEVEL=INFO

Step 3. Replace Your Imports

Before:

import { GoogleGenerativeAI } from "@google/generative-ai";

After:

import { GoogleGenAIController } from "@revenium/google-genai";

Step 4. Update Your Code

Basic usage pattern:

import { GoogleGenAIController } from "@revenium/google-genai";

const controller = new GoogleGenAIController();
const result = await controller.createChat(
  ["Your prompt here"],
  "gemini-2.0-flash-001", // required model parameter
);

For complete working examples, see:

• Google AI Basic Example - Chat, streaming, and embeddings
• Google AI Streaming Example - Advanced streaming patterns
• Google AI Embedding Example - Text embeddings

Advanced Usage

Streaming Responses

Basic streaming pattern:

const result = await controller.createStreaming(
  ["Your prompt here"],
  "gemini-2.0-flash-001",
);

for await (const chunk of result.stream) {
  // Process streaming chunks
}

For complete streaming examples with performance tracking and metadata, see:

• Google AI Streaming Example

Text Embeddings

Basic embedding pattern:

const result = await controller.createEmbedding(
  "Text to embed",
  "text-embedding-004",
);

For complete embedding examples with metadata and batch processing, see:

• Google AI Embedding Example

Custom Metadata Tracking

Add business context to your AI usage. See the Revenium Metering API Reference for complete header options.

Metadata Fields

The usageMetadata parameter supports the following fields for detailed tracking:

| Field | Description | Use Case | | -------------------------- | ---------------------------------------- | ------------------------------ | | traceId | Session/conversation tracking identifier | Distributed tracing, debugging | | taskType | AI task categorization | Cost analysis by workload type | | subscriberId | User identifier | Billing, rate limiting | | subscriberEmail | User email address | Support, compliance | | subscriberCredentialName | Auth credential name | Track API keys | | subscriberCredential | Auth credential value | Security auditing | | organizationId | Organization ID | Multi-tenant cost allocation | | subscriptionId | Subscription plan ID | Plan limit tracking | | productId | Product/feature ID | Feature cost attribution | | agent | AI agent identifier | Distinguish workflows | | responseQualityScore | Quality rating 0.0-1.0 | Performance analysis | | modelSource | Routing layer (e.g., DIRECT, GOOGLE) | Integration analytics | | systemFingerprint | Provider-issued model fingerprint | Debugging and attribution | | temperature | Sampling temperature applied | Compare response creativity | | errorReason | Upstream error message | Error monitoring | | mediationLatency | Gateway latency in ms | Diagnose mediation overhead |

Note: The Google middleware accepts these fields in a flat structure. Internally, subscriber fields are transformed to a nested structure (subscriber.id, subscriber.email, subscriber.credential.name, subscriber.credential.value) before being sent to the Revenium API.

Usage Example

Basic pattern with metadata:

const customMetadata = {
  subscriberId: "user-123",
  subscriberEmail: "[email protected]",
  organizationId: "org-456",
  productId: "chat-app",
};

const result = await controller.createChat(
  ["Your prompt here"],
  "gemini-2.0-flash-001", // required model parameter
  customMetadata, // optional metadata parameter
);

For complete metadata examples with all available fields, see:

• Google AI Basic Example
• Google AI Streaming Example
• Google AI Embedding Example

Trace Visualization Fields

The middleware automatically captures trace visualization fields for distributed tracing and analytics:

| Field | Type | Description | Environment Variable | | --------------------- | ------ | ------------------------------------------------------------------------------- | ---------------------------------- | | environment | string | Deployment environment (production, staging, development) | REVENIUM_ENVIRONMENT, NODE_ENV | | operationType | string | Operation classification (CHAT, EMBED, etc.) - automatically detected | N/A (auto-detected) | | operationSubtype | string | Additional detail (function_call, etc.) - automatically detected | N/A (auto-detected) | | retryNumber | number | Retry attempt number (0 for first attempt, 1+ for retries) | REVENIUM_RETRY_NUMBER | | parentTransactionId | string | Parent transaction reference for distributed tracing | REVENIUM_PARENT_TRANSACTION_ID | | transactionName | string | Human-friendly operation label | REVENIUM_TRANSACTION_NAME | | region | string | Cloud region (us-east-1, etc.) - auto-detected from AWS/Azure/GCP | AWS_REGION, REVENIUM_REGION | | credentialAlias | string | Human-readable credential name | REVENIUM_CREDENTIAL_ALIAS | | traceType | string | Categorical identifier (alphanumeric, hyphens, underscores only, max 128 chars) | REVENIUM_TRACE_TYPE | | traceName | string | Human-readable label for trace instances (max 256 chars) | REVENIUM_TRACE_NAME |

All trace visualization fields are optional. The middleware will automatically detect and populate these fields when possible.

Example Configuration

REVENIUM_ENVIRONMENT=production
REVENIUM_REGION=us-east-1
REVENIUM_CREDENTIAL_ALIAS=Google AI Production Key
REVENIUM_TRACE_TYPE=customer_support
REVENIUM_TRACE_NAME=Support Ticket #12345
REVENIUM_PARENT_TRANSACTION_ID=parent-txn-123
REVENIUM_TRANSACTION_NAME=Answer Customer Question
REVENIUM_RETRY_NUMBER=0

What Gets Tracked

• Token Usage: Input and output tokens for accurate billing
• Request Duration: Total time for each API call
• Model Information: Which model was used
• Operation Type: Chat completion, embedding, streaming
• Error Tracking: Failed requests and error details
• Streaming Metrics: Time to first token for streaming responses

Supported Models

Important: The model parameter is required when calling any controller method. You must specify the model explicitly in your code.

This middleware supports all models available in Google AI Studio. The middleware does not maintain a hardcoded list of models, ensuring compatibility with new models as Google releases them.

For the latest available models, see:

• Google AI Gemini Model Reference

Example usage:

// Without metadata (clean, simple)
const result = await controller.createChat(
  ["Your prompt here"],
  "gemini-2.0-flash-001", // required model parameter
);

// With metadata (optional)
const metadata = {
  subscriberId: "user-123",
  subscriberEmail: "[email protected]",
  organizationId: "org-456",
  productId: "product-789",
};

const resultWithMetadata = await controller.createChat(
  ["Your prompt here"],
  "gemini-2.0-flash-001",
  metadata, // optional metadata parameter
);

For complete examples with different models and use cases, see:

• Google AI Basic Example - Chat and embeddings with various models
• Google AI Streaming Example - Streaming with different configurations

Configuration Options

Environment Variables

Required:

• GOOGLE_API_KEY - Your Google AI API key from Google AI Studio
• REVENIUM_METERING_API_KEY - Your Revenium API key from Revenium Dashboard

Optional:

• REVENIUM_METERING_BASE_URL - Revenium API base URL (defaults to https://api.revenium.ai, only needed for development/testing)
• REVENIUM_LOG_LEVEL - Log level: DEBUG, INFO, WARN, ERROR (defaults to INFO)
• REVENIUM_PRINT_SUMMARY - Print cost/metrics summary to console after each request: true, false, "human", or "json" (defaults to false)
• REVENIUM_TEAM_ID - Your Revenium team ID (required for cost metrics in summary output)
• REVENIUM_CAPTURE_PROMPTS - Capture prompts and responses for analysis: true or false (defaults to false)

Prompt Capture

The middleware can capture prompts and responses for analysis and debugging. This feature is disabled by default for privacy and performance.

Configuration

Enable via environment variable:

REVENIUM_CAPTURE_PROMPTS=true

Per-Request Control

Override the global setting for individual requests:

import { GoogleGenAIController } from "@revenium/google-genai";

const controller = new GoogleGenAIController();
const result = await controller.createChat(
  ["What is artificial intelligence?"],
  "gemini-2.0-flash-001",
  {
    capturePrompts: true,
  },
);

Security

All captured prompts are automatically sanitized to remove sensitive credentials including:

• API keys (sk-*, sk-proj-*, sk-ant-*, AIzaSy*)
• Bearer tokens
• Passwords
• Generic tokens and api_key fields

Manual Configuration

Controllers read configuration from environment variables:

export GOOGLE_API_KEY="your-api-key"
export REVENIUM_METERING_API_KEY="your-revenium-key"

# Optional: Only for development/testing
# export REVENIUM_METERING_BASE_URL="https://api.revenium.ai"

Then instantiate the controller:

import { GoogleGenAIController } from "@revenium/google-genai";

const controller = new GoogleGenAIController();
const response = await controller.createChat(
  ["Hello world"],
  "gemini-2.0-flash-001",
);

For complete configuration examples, see:

• Google AI Basic Example

Troubleshooting

Common Issues

"Missing API Key" Error

export GOOGLE_API_KEY="your-actual-api-key"
echo $GOOGLE_API_KEY  # Verify it's set

"Requests not being tracked"

export REVENIUM_METERING_API_KEY="your-actual-revenium-key"
export REVENIUM_LOG_LEVEL="DEBUG"  # Enable debug logging

Module Import Errors

{
  "type": "module"
}

Requirements

• Node.js 18+
• Google AI API key
• Revenium API key

Documentation

For detailed documentation, visit docs.revenium.io

Contributing

See CONTRIBUTING.md

Code of Conduct

See CODE_OF_CONDUCT.md

Security

See SECURITY.md

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

For issues, feature requests, or contributions:

• GitHub Repository: revenium/revenium-middleware-google-node
• Issues: Report bugs or request features
• Documentation: docs.revenium.io
• Contact: Reach out to the Revenium team for additional support

Local Development and Contributing

Are you planning to modify the middleware source code? (Not just run examples)

If you want to:

• Fix bugs in the middleware
• Add new features to @revenium/google-genai
• Contribute to the project
• Test changes to the middleware before publishing

Then follow the complete development workflow in DEVELOPMENT.md, which covers:

What DEVELOPMENT.md Includes:

• Development Workflow - Step-by-step process for making changes
• Build System - Understanding the monorepo and TypeScript compilation
• Testing Local Changes - How to test your modifications properly
• When to Rebuild - Understanding when npm run build is needed
• Publishing Checklist - Steps to publish new versions
• Architecture Notes - Understanding the codebase structure
• Contributing Guidelines - How to contribute to the project

Key Difference:

• Running Examples (above): You can modify example files and run them directly with npx tsx - no rebuild needed
• Modifying Middleware (DEVELOPMENT.md): If you modify source files in packages/google-genai/src/, you must run npm run build before testing

Quick Start for Contributors:

# 1. Make changes to source code
vim packages/google-genai/src/googleGenAI.service.ts

# 2. Rebuild the package
npm run build

# 3. Test your changes
npm run example:genai:getting-started

# 4. See DEVELOPMENT.md for complete workflow

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