Gemini CLI to API Proxy

A proxy server that converts Google's Gemini CLI authentication to standard API format, allowing you to use Gemini models with any OpenAI-compatible client.

Features

OAuth 2.0 authentication with Google Cloud
Automatic project ID detection and caching
Support for both streaming and non-streaming requests
Converts Google's internal API format to standard Gemini API format
Credential caching for seamless restarts

Prerequisites

Python 3.7 or higher
Google Cloud account with Gemini API access
Required Python packages (see requirements.txt)

Installation

Clone or download this repository
Install the required dependencies:
```
pip install -r requirements.txt
```

Setup and Usage

First Time Setup

Start the proxy server:
```
python gemini_proxy.py
```
Authenticate with Google:
- On first run, the proxy will display an authentication URL
- Open the URL in your browser and sign in with your Google account
- Grant the necessary permissions
- The browser will show "Authentication successful!" when complete
- The proxy will automatically save your credentials for future use
Project ID Detection:
- The proxy will automatically detect and cache your Google Cloud project ID
- This only happens once - subsequent runs will use the cached project ID

Regular Usage

After initial setup, simply run:

python gemini_proxy.py

The proxy server will start on http://localhost:8888 and display:

Starting Gemini proxy server on http://localhost:8888
Send your Gemini API requests to this address.

Using with API Clients

Configure your Gemini API client to use http://localhost:8888 as the base URL. The proxy accepts standard Gemini API requests and handles the authentication automatically.

Example request:

curl -X POST http://localhost:8888/v1/models/gemini-pro:generateContent \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [{
      "parts": [{"text": "Hello, how are you?"}]
    }]
  }'

Configuration

The proxy uses the following configuration:

Port: 8888 (hardcoded)
Credential file: oauth_creds.json (automatically created)
Scopes: Cloud Platform, User Info (email/profile), OpenID

File Structure

gemini_proxy.py - Main proxy server
oauth_creds.json - Cached OAuth credentials and project ID (auto-generated)
requirements.txt - Python dependencies
.gitignore - Prevents credential files from being committed

Troubleshooting

Port Already in Use

If you see "error while attempting to bind on address", another instance is already running. Stop the existing process or use a different port.

Authentication Issues

Delete oauth_creds.json and restart to re-authenticate
Ensure your Google account has access to Google Cloud and Gemini API
Check that the required scopes are granted during authentication

Project ID Issues

The proxy automatically detects your project ID on first run
If detection fails, check your Google Cloud project permissions
Delete oauth_creds.json to force re-detection

Security Notes

Never commit oauth_creds.json - it contains sensitive authentication tokens
The .gitignore file is configured to prevent accidental commits
Credentials are stored locally and refreshed automatically when expired
The proxy runs on localhost only for security

API Compatibility

This proxy converts between:

Input: Standard Gemini API format
Output: Standard Gemini API responses
Internal: Google's Cloud Code Assist API format

The conversion is transparent to API clients.