client: improve error messaging on connection failure (#398)

*iImprove error messaging on connection failure

examples/create.py

@@ -2,9 +2,9 @@ from ollama import Client
 
 client = Client()
 response = client.create(
-    model='my-assistant',
+  model='my-assistant',
-    from_='llama3.2',
+  from_='llama3.2',
-    system="You are mario from Super Mario Bros.",
+  system='You are mario from Super Mario Bros.',
-    stream=False
+  stream=False,
 )
 print(response.status)

ollama/_client.py

@@ -106,17 +106,22 @@ class BaseClient:
     )
 
 
+CONNECTION_ERROR_MESSAGE = 'Failed to connect to Ollama. Please check that Ollama is downloaded, running and accessible. https://ollama.com/download'
+
+
 class Client(BaseClient):
   def __init__(self, host: Optional[str] = None, **kwargs) -> None:
     super().__init__(httpx.Client, host, **kwargs)
 
   def _request_raw(self, *args, **kwargs):
-    r = self._client.request(*args, **kwargs)
     try:
+      r = self._client.request(*args, **kwargs)
       r.raise_for_status()
+      return r
     except httpx.HTTPStatusError as e:
       raise ResponseError(e.response.text, e.response.status_code) from None
-    return r
+    except httpx.ConnectError:
+      raise ConnectionError(CONNECTION_ERROR_MESSAGE) from None
 
   @overload
   def _request(
@@ -613,12 +618,14 @@ class AsyncClient(BaseClient):
     super().__init__(httpx.AsyncClient, host, **kwargs)
 
   async def _request_raw(self, *args, **kwargs):
-    r = await self._client.request(*args, **kwargs)
     try:
+      r = await self._client.request(*args, **kwargs)
       r.raise_for_status()
+      return r
     except httpx.HTTPStatusError as e:
       raise ResponseError(e.response.text, e.response.status_code) from None
-    return r
+    except httpx.ConnectError:
+      raise ConnectionError(CONNECTION_ERROR_MESSAGE) from None
 
   @overload
   async def _request(

ollama/_types.py

@@ -535,3 +535,6 @@ class ResponseError(Exception):
 
     self.status_code = status_code
     'HTTP status code of the response.'
+
+  def __str__(self) -> str:
+    return f'{self.error} (status code: {self.status_code})'

tests/test_client.py

@@ -9,7 +9,7 @@ from pydantic import BaseModel, ValidationError
 from pytest_httpserver import HTTPServer, URIPattern
 from werkzeug.wrappers import Request, Response
 
-from ollama._client import AsyncClient, Client, _copy_tools
+from ollama._client import CONNECTION_ERROR_MESSAGE, AsyncClient, Client, _copy_tools
 
 PNG_BASE64 = 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVR4nGNgYGAAAAAEAAH2FzhVAAAAAElFTkSuQmCC'
 PNG_BYTES = base64.b64decode(PNG_BASE64)
@@ -1112,3 +1112,30 @@ def test_tool_validation():
   with pytest.raises(ValidationError):
     invalid_tool = {'type': 'invalid_type', 'function': {'name': 'test'}}
     list(_copy_tools([invalid_tool]))
+
+
+def test_client_connection_error():
+  client = Client('http://localhost:1234')
+
+  with pytest.raises(ConnectionError, match=CONNECTION_ERROR_MESSAGE):
+    client.chat('model', messages=[{'role': 'user', 'content': 'prompt'}])
+  with pytest.raises(ConnectionError, match=CONNECTION_ERROR_MESSAGE):
+    client.chat('model', messages=[{'role': 'user', 'content': 'prompt'}])
+  with pytest.raises(ConnectionError, match=CONNECTION_ERROR_MESSAGE):
+    client.generate('model', 'prompt')
+  with pytest.raises(ConnectionError, match=CONNECTION_ERROR_MESSAGE):
+    client.show('model')
+
+
+@pytest.mark.asyncio
+async def test_async_client_connection_error():
+  client = AsyncClient('http://localhost:1234')
+  with pytest.raises(ConnectionError) as exc_info:
+    await client.chat('model', messages=[{'role': 'user', 'content': 'prompt'}])
+  assert str(exc_info.value) == 'Failed to connect to Ollama. Please check that Ollama is downloaded, running and accessible. https://ollama.com/download'
+  with pytest.raises(ConnectionError) as exc_info:
+    await client.generate('model', 'prompt')
+  assert str(exc_info.value) == 'Failed to connect to Ollama. Please check that Ollama is downloaded, running and accessible. https://ollama.com/download'
+  with pytest.raises(ConnectionError) as exc_info:
+    await client.show('model')
+  assert str(exc_info.value) == 'Failed to connect to Ollama. Please check that Ollama is downloaded, running and accessible. https://ollama.com/download'