# OAuth2 LLM Providers

CrewAI supports OAuth2 authentication for custom LiteLLM providers through configuration files.

## Features

- **Automatic Token Management**: Handles OAuth2 token acquisition and refresh automatically
- **Multiple Provider Support**: Configure multiple OAuth2 providers in a single configuration file
- **Secure Credential Storage**: Keep OAuth2 credentials separate from your code
- **Seamless Integration**: Works with existing LiteLLM provider configurations
- **Error Handling**: Comprehensive error handling for authentication failures
- **Retry Mechanism**: Automatic retry with exponential backoff for token acquisition
- **Thread Safety**: Concurrent access protection for token caching
- **Configuration Validation**: Automatic validation of URLs and scope formats

## Error Handling

The OAuth2 implementation provides specific error classes for different failure scenarios:

### OAuth2ConfigurationError
Raised when there are issues with the OAuth2 configuration:
- Invalid configuration file format
- Missing required fields
- Unknown OAuth2 providers

### OAuth2AuthenticationError  
Raised when OAuth2 authentication fails:
- Network errors during token acquisition
- Invalid credentials
- Token endpoint errors

### OAuth2ValidationError
Raised when configuration validation fails:
- Invalid URL formats
- Malformed scope values

### Example Error Handling

```python
from crewai import LLM
from crewai.llms.oauth2_errors import OAuth2ConfigurationError, OAuth2AuthenticationError

try:
    llm = LLM(
        model="my_custom_provider/my-model",
        oauth2_config_path="./litellm_config.json"
    )
    result = llm.call("test message")
except OAuth2ConfigurationError as e:
    print(f"Configuration error: {e}")
except OAuth2AuthenticationError as e:
    print(f"Authentication failed: {e}")
    if e.original_error:
        print(f"Original error: {e.original_error}")
```

## Configuration Validation

The OAuth2 configuration is automatically validated:

- **URL Validation**: `token_url` must be a valid HTTP/HTTPS URL
- **Scope Validation**: `scope` cannot contain empty values when split by spaces
- **Required Fields**: `client_id`, `client_secret`, `token_url`, and `provider_name` are required

## Retry Mechanism

Token acquisition includes automatic retry with exponential backoff:
- 3 retry attempts by default
- Exponential backoff: 1s, 2s, 4s delays
- Detailed logging of retry attempts
- Thread-safe token caching

## Configuration

Create a `litellm_config.json` file in your project directory:

```json
{
  "oauth2_providers": {
    "my_custom_provider": {
      "client_id": "your_client_id",
      "client_secret": "your_client_secret", 
      "token_url": "https://your-provider.com/oauth/token",
      "scope": "llm.read llm.write"
    },
    "another_provider": {
      "client_id": "another_client_id",
      "client_secret": "another_client_secret",
      "token_url": "https://another-provider.com/token"
    }
  }
}
```

## Usage

```python
from crewai import LLM

# Initialize LLM with OAuth2 support
llm = LLM(
    model="my_custom_provider/my-model",
    oauth2_config_path="./litellm_config.json"  # Optional, defaults to ./litellm_config.json
)

# Use in CrewAI
from crewai import Agent, Task, Crew

agent = Agent(
    role="Data Analyst",
    goal="Analyze data trends",
    backstory="Expert in data analysis",
    llm=llm
)

task = Task(
    description="Analyze the latest sales data",
    agent=agent
)

crew = Crew(agents=[agent], tasks=[task])
result = crew.kickoff()
```

## Environment Variables

You can also use environment variables in your configuration:

```json
{
  "oauth2_providers": {
    "my_provider": {
      "client_id": "os.environ/MY_CLIENT_ID",
      "client_secret": "os.environ/MY_CLIENT_SECRET",
      "token_url": "https://my-provider.com/token"
    }
  }
}
```

## Supported OAuth2 Flow

Currently supports the **Client Credentials** OAuth2 flow, which is suitable for server-to-server authentication.

## Token Management

- Tokens are automatically cached and refreshed when they expire
- A 60-second buffer is used before token expiration to ensure reliability
- Failed token acquisition will raise a `RuntimeError` with details

## Configuration Schema

The `litellm_config.json` file should follow this schema:

```json
{
  "oauth2_providers": {
    "<provider_name>": {
      "client_id": "string (required)",
      "client_secret": "string (required)",
      "token_url": "string (required)",
      "scope": "string (optional)",
      "refresh_token": "string (optional)"
    }
  }
}
```

## Legacy Error Handling

For backward compatibility, the following error types are still supported:
- OAuth2 authentication failures raise `OAuth2AuthenticationError` (previously `RuntimeError`)
- Invalid configuration files raise `OAuth2ConfigurationError` (previously `ValueError`)
- Network errors during token acquisition are wrapped in `OAuth2AuthenticationError`

## Examples

### Basic OAuth2 Provider

```python
from crewai import LLM

llm = LLM(
    model="my_provider/gpt-4",
    oauth2_config_path="./config.json"
)

response = llm.call("Hello, world!")
print(response)
```

### Multiple Providers

```json
{
  "oauth2_providers": {
    "provider_a": {
      "client_id": "client_a",
      "client_secret": "secret_a",
      "token_url": "https://provider-a.com/token"
    },
    "provider_b": {
      "client_id": "client_b", 
      "client_secret": "secret_b",
      "token_url": "https://provider-b.com/oauth/token",
      "scope": "read write"
    }
  }
}
```

```python
# Use different providers
llm_a = LLM(model="provider_a/model-1", oauth2_config_path="./config.json")
llm_b = LLM(model="provider_b/model-2", oauth2_config_path="./config.json")
```