Add an OpenRouter provider (#921)

* Move _get_base_url to the base provider

In order to properly support "muxing providers" like openrouter, we'll
have to tell litellm (or in future a native implementation), what server
do we want to proxy to. We were already doing that with Vllm, but since
are about to do the same for OpenRouter, let's move the `_get_base_url`
method to the base provider.

* Add an openrouter provider

OpenRouter is a "muxing provider" which itself provides access to
multiple models and providers. It speaks a dialect of the OpenAI protocol, but
for our purposes, we can say it's OpenAI.

There are some differences in handling the requests, though:
1) we need to know where to forward the request to, by default this is
   `https://openrouter.ai/api/v1`, this is done by setting the base_url
   parameter
2) we need to prefix the model with `openrouter/`. This is a
   lite-LLM-ism (see https://docs.litellm.ai/docs/providers/openrouter)
   which we'll be able to remove once we ditch litellm

Initially I was considering just exposing the OpenAI provider on an
additional route and handling the prefix based on the route, but I think
having an explicit provider class is better as it allows us to handle
any differences in OpenRouter dialect easily in the future.

Related: #878

* Add a special ProviderType for openrouter

We can later alias it to openai if we decide to merge them.

* Add tests for the openrouter provider

* ProviderType was reversed, thanks Alejandro

---------

Co-authored-by: Radoslav Dimitrov <[email protected]>

src/codegate/config.py

@@ -17,6 +17,7 @@
 # Default provider URLs
 DEFAULT_PROVIDER_URLS = {
     "openai": "https://api.openai.com/v1",
+    "openrouter": "https://openrouter.ai/api/v1",
     "anthropic": "https://api.anthropic.com/v1",
     "vllm": "http://localhost:8000",  # Base URL without /v1 path
     "ollama": "http://localhost:11434",  # Default Ollama server URL

src/codegate/db/models.py

@@ -128,6 +128,7 @@ class ProviderType(str, Enum):
     ollama = "ollama"
     lm_studio = "lm_studio"
     llamacpp = "llamacpp"
+    openrouter = "openai"
 
 
 class GetPromptWithOutputsRow(BaseModel):

src/codegate/muxing/adapter.py

@@ -106,6 +106,8 @@ def __init__(self):
             db_models.ProviderType.anthropic: self._format_antropic,
             # Our Lllamacpp provider emits OpenAI chunks
             db_models.ProviderType.llamacpp: self._format_openai,
+            # OpenRouter is a dialect of OpenAI
+            db_models.ProviderType.openrouter: self._format_openai,
         }
 
     def _format_ollama(self, chunk: str) -> str:

src/codegate/providers/__init__.py

@@ -2,13 +2,15 @@
 from codegate.providers.base import BaseProvider
 from codegate.providers.ollama.provider import OllamaProvider
 from codegate.providers.openai.provider import OpenAIProvider
+from codegate.providers.openrouter.provider import OpenRouterProvider
 from codegate.providers.registry import ProviderRegistry
 from codegate.providers.vllm.provider import VLLMProvider
 
 __all__ = [
     "BaseProvider",
     "ProviderRegistry",
     "OpenAIProvider",
+    "OpenRouterProvider",
     "AnthropicProvider",
     "VLLMProvider",
     "OllamaProvider",

src/codegate/providers/base.py

@@ -12,6 +12,7 @@
 
 from codegate.clients.clients import ClientType
 from codegate.codegate_logging import setup_logging
+from codegate.config import Config
 from codegate.db.connection import DbRecorder
 from codegate.pipeline.base import (
     PipelineContext,
@@ -88,6 +89,13 @@ async def process_request(
     def provider_route_name(self) -> str:
         pass
 
+    def _get_base_url(self) -> str:
+        """
+        Get the base URL from config with proper formatting
+        """
+        config = Config.get_config()
+        return config.provider_urls.get(self.provider_route_name) if config else ""
+
     async def _run_output_stream_pipeline(
         self,
         input_context: PipelineContext,

src/codegate/providers/openai/__init__.py

@@ -0,0 +1,3 @@
+from codegate.providers.openai.provider import OpenAIProvider
+
+__all__ = ["OpenAIProvider"]

src/codegate/providers/openrouter/provider.py

@@ -0,0 +1,47 @@
+import json
+
+from fastapi import Header, HTTPException, Request
+
+from codegate.clients.detector import DetectClient
+from codegate.pipeline.factory import PipelineFactory
+from codegate.providers.openai import OpenAIProvider
+
+
+class OpenRouterProvider(OpenAIProvider):
+    def __init__(self, pipeline_factory: PipelineFactory):
+        super().__init__(pipeline_factory)
+
+    @property
+    def provider_route_name(self) -> str:
+        return "openrouter"
+
+    def _setup_routes(self):
+        @self.router.post(f"/{self.provider_route_name}/api/v1/chat/completions")
+        @self.router.post(f"/{self.provider_route_name}/chat/completions")
+        @DetectClient()
+        async def create_completion(
+            request: Request,
+            authorization: str = Header(..., description="Bearer token"),
+        ):
+            if not authorization.startswith("Bearer "):
+                raise HTTPException(status_code=401, detail="Invalid authorization header")
+
+            api_key = authorization.split(" ")[1]
+            body = await request.body()
+            data = json.loads(body)
+
+            base_url = self._get_base_url()
+            data["base_url"] = base_url
+
+            # litellm workaround - add openrouter/ prefix to model name to make it openai-compatible
+            # once we get rid of litellm, this can simply be removed
+            original_model = data.get("model", "")
+            if not original_model.startswith("openrouter/"):
+                data["model"] = f"openrouter/{original_model}"
+
+            return await self.process_request(
+                data,
+                api_key,
+                request.url.path,
+                request.state.detected_client,
+            )

src/codegate/providers/vllm/provider.py

@@ -9,7 +9,6 @@
 
 from codegate.clients.clients import ClientType
 from codegate.clients.detector import DetectClient
-from codegate.config import Config
 from codegate.pipeline.factory import PipelineFactory
 from codegate.providers.base import BaseProvider, ModelFetchError
 from codegate.providers.litellmshim import LiteLLmShim, sse_stream_generator
@@ -39,8 +38,7 @@ def _get_base_url(self) -> str:
         """
         Get the base URL from config with proper formatting
         """
-        config = Config.get_config()
-        base_url = config.provider_urls.get("vllm") if config else ""
+        base_url = super()._get_base_url()
         if base_url:
             base_url = base_url.rstrip("/")
             # Add /v1 if not present

src/codegate/server.py

@@ -18,6 +18,7 @@
 from codegate.providers.lm_studio.provider import LmStudioProvider
 from codegate.providers.ollama.provider import OllamaProvider
 from codegate.providers.openai.provider import OpenAIProvider
+from codegate.providers.openrouter.provider import OpenRouterProvider
 from codegate.providers.registry import ProviderRegistry, get_provider_registry
 from codegate.providers.vllm.provider import VLLMProvider
 
@@ -75,6 +76,10 @@ async def log_user_agent(request: Request, call_next):
         ProviderType.openai,
         OpenAIProvider(pipeline_factory),
     )
+    registry.add_provider(
+        ProviderType.openrouter,
+        OpenRouterProvider(pipeline_factory),
+    )
     registry.add_provider(
         ProviderType.anthropic,
         AnthropicProvider(

tests/providers/openrouter/test_openrouter_provider.py

@@ -0,0 +1,98 @@
+import json
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+from fastapi import HTTPException
+from fastapi.requests import Request
+
+from codegate.config import DEFAULT_PROVIDER_URLS
+from codegate.pipeline.factory import PipelineFactory
+from codegate.providers.openrouter.provider import OpenRouterProvider
+
+
+@pytest.fixture
+def mock_factory():
+    return MagicMock(spec=PipelineFactory)
+
+
+@pytest.fixture
+def provider(mock_factory):
+    return OpenRouterProvider(mock_factory)
+
+
+def test_get_base_url(provider):
+    """Test that _get_base_url returns the correct OpenRouter API URL"""
+    assert provider._get_base_url() == DEFAULT_PROVIDER_URLS["openrouter"]
+
+
+@pytest.mark.asyncio
+async def test_model_prefix_added():
+    """Test that model name gets prefixed with openrouter/ when not already present"""
+    mock_factory = MagicMock(spec=PipelineFactory)
+    provider = OpenRouterProvider(mock_factory)
+    provider.process_request = AsyncMock()
+
+    # Mock request
+    mock_request = MagicMock(spec=Request)
+    mock_request.body = AsyncMock(return_value=json.dumps({"model": "gpt-4"}).encode())
+    mock_request.url.path = "/openrouter/chat/completions"
+    mock_request.state.detected_client = "test-client"
+
+    # Get the route handler function
+    route_handlers = [
+        route for route in provider.router.routes if route.path == "/openrouter/chat/completions"
+    ]
+    create_completion = route_handlers[0].endpoint
+
+    await create_completion(request=mock_request, authorization="Bearer test-token")
+
+    # Verify process_request was called with prefixed model
+    call_args = provider.process_request.call_args[0]
+    assert call_args[0]["model"] == "openrouter/gpt-4"
+
+
+@pytest.mark.asyncio
+async def test_model_prefix_preserved():
+    """Test that model name is not modified when openrouter/ prefix is already present"""
+    mock_factory = MagicMock(spec=PipelineFactory)
+    provider = OpenRouterProvider(mock_factory)
+    provider.process_request = AsyncMock()
+
+    # Mock request
+    mock_request = MagicMock(spec=Request)
+    mock_request.body = AsyncMock(return_value=json.dumps({"model": "openrouter/gpt-4"}).encode())
+    mock_request.url.path = "/openrouter/chat/completions"
+    mock_request.state.detected_client = "test-client"
+
+    # Get the route handler function
+    route_handlers = [
+        route for route in provider.router.routes if route.path == "/openrouter/chat/completions"
+    ]
+    create_completion = route_handlers[0].endpoint
+
+    await create_completion(request=mock_request, authorization="Bearer test-token")
+
+    # Verify process_request was called with unchanged model name
+    call_args = provider.process_request.call_args[0]
+    assert call_args[0]["model"] == "openrouter/gpt-4"
+
+
+@pytest.mark.asyncio
+async def test_invalid_auth_header():
+    """Test that invalid authorization header format raises HTTPException"""
+    mock_factory = MagicMock(spec=PipelineFactory)
+    provider = OpenRouterProvider(mock_factory)
+
+    mock_request = MagicMock(spec=Request)
+
+    # Get the route handler function
+    route_handlers = [
+        route for route in provider.router.routes if route.path == "/openrouter/chat/completions"
+    ]
+    create_completion = route_handlers[0].endpoint
+
+    with pytest.raises(HTTPException) as exc_info:
+        await create_completion(request=mock_request, authorization="InvalidToken")
+
+    assert exc_info.value.status_code == 401
+    assert exc_info.value.detail == "Invalid authorization header"

tests/test_server.py

@@ -108,8 +108,8 @@ def test_provider_registration(mock_registry, mock_secrets_mgr, mock_pipeline_fa
     # Verify all providers were registered
     registry_instance = mock_registry.return_value
     assert (
-        registry_instance.add_provider.call_count == 6
-    )  # openai, anthropic, llamacpp, vllm, ollama, lm_studio
+        registry_instance.add_provider.call_count == 7
+    )  # openai, anthropic, llamacpp, vllm, ollama, lm_studio, openrouter
 
     # Verify specific providers were registered
     provider_names = [call.args[0] for call in registry_instance.add_provider.call_args_list]