Optionally import httpx in async service (#1508)

**Pull Request Checklist**
- [ ] Fixes #<!--issue number goes here-->
- [ ] Tests added
- [ ] Documentation/examples added
- [x] [Good commit messages](https://cbea.ms/git-commit/) and/or PR
title

**Description of PR**

importing hera 5.25.0 breaks because it tries to import httpx anyway.
(httpx is installed when hera is installed with async-client extras)


https://github.com/argoproj-labs/hera/blob/5072bb938ecd46a1ab7a229eaf7927ee15faa105/src/hera/workflows/__init__.py#L23


https://github.com/argoproj-labs/hera/blob/5072bb938ecd46a1ab7a229eaf7927ee15faa105/src/hera/workflows/async_service.py#L8

so in this pr, importing httpx only will be done when it is used.

Signed-off-by: Ukjae Jeong <JeongUkJae@gmail.com>

Author: jeongukjae

scripts/async_service.py

@@ -182,7 +182,7 @@ def __str__(self) -> str:
 
         if resp.is_success:
             return {ret_val}
-        
+
         raise exception_from_server_response(resp)
 """
 
@@ -397,16 +397,18 @@ def get_service_def() -> str:
 \"\"\"Interact with the {doc_models_type} REST service asynchronously. Requires you to `pip install hera[async-client]`.\"\"\"
 # [DO NOT MODIFY] Auto-generated by `hera/scripts/async_service.py`
 from urllib.parse import urljoin
-import httpx
 import os
 from hera.{module}.models import {imports}
 from hera.shared import global_config
 from hera.exceptions import exception_from_server_response
-from typing import Optional, Tuple, cast
+from typing import Optional, Tuple, cast, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    import httpx
 
 def valid_host_scheme(host: str) -> bool:
     \"\"\"Validates the the given `host` starts with either `http` or `https`.\"\"\"
-    return host.startswith("http://") or host.startswith("https://")    
+    return host.startswith("http://") or host.startswith("https://")
 
 class {models_type}Service:
     \"\"\"The asynchronous {doc_models_type} service for interacting with the Argo server.\"\"\"
@@ -417,20 +419,22 @@ def __init__(
         token: Optional[str] = None,
         client_certs: Optional[Tuple[str, str]] = None,
         namespace: Optional[str] = None,
-        session: Optional[httpx.AsyncClient] = None,
+        session: Optional["httpx.AsyncClient"] = None,
     ) -> None:
         \"\"\"{models_type} service constructor.\"\"\"
+        import httpx
+
         self.host = cast(str, host or global_config.host)
         self.verify_ssl = verify_ssl if verify_ssl is not None else global_config.verify_ssl
         self.client_certs = client_certs if client_certs is not None else global_config.client_certs
 
-        # some users reported in https://github.com/argoproj-labs/hera/issues/1016 that it can be a bit awkward for 
+        # some users reported in https://github.com/argoproj-labs/hera/issues/1016 that it can be a bit awkward for
         # Hera to assume a `Bearer` prefix on behalf of users. Some might pass it and some might not. Therefore, Hera
         # only prefixes the token with `Bearer ` if it's not already specified and lets the uses specify it otherwise.
-        # Note that the `Bearer` token can be specified through the global configuration as well. In order to deliver 
+        # Note that the `Bearer` token can be specified through the global configuration as well. In order to deliver
         # a fix on Hera V5 without introducing breaking changes, we have to support both
         global_config_token = global_config.token  # call only once because it can be a user specified function!
-        
+
         def format_token(t):
             parts = t.strip().split()
             if len(parts) == 1:
@@ -447,19 +451,19 @@ def format_token(t):
         self.session = session or httpx.AsyncClient(verify=self.verify_ssl, cert=self.client_certs)
 
         self.namespace = namespace or global_config.namespace
-        
+
     async def _request(self, method, **kwargs):
         \"\"\"Make a request using the session if enabled.\"\"\"
         return await self.session.request(method, **kwargs)
-    
+
     async def close(self):
         \"\"\"Close the service session.\"\"\"
-        await self.session.aclose()    
-    
+        await self.session.aclose()
+
     async def __aenter__(self):
         \"\"\"Open the service - session doesn't need to be opened.\"\"\"
         return self
-        
+
     async def __aexit__(self, *_):
         \"\"\"Close the service.\"\"\"
         await self.close()

src/hera/events/async_service.py

@@ -1,11 +1,9 @@
 """Interact with the events REST service asynchronously. Requires you to `pip install hera[async-client]`."""
 
 # [DO NOT MODIFY] Auto-generated by `hera/scripts/async_service.py`
-from typing import Optional, Tuple, cast
+from typing import TYPE_CHECKING, Optional, Tuple, cast
 from urllib.parse import urljoin
 
-import httpx
-
 from hera.events.models import (
     CreateEventSourceRequest,
     CreateSensorRequest,
@@ -31,6 +29,9 @@
 from hera.exceptions import exception_from_server_response
 from hera.shared import global_config
 
+if TYPE_CHECKING:
+    import httpx
+
 
 def valid_host_scheme(host: str) -> bool:
     """Validates the the given `host` starts with either `http` or `https`."""
@@ -47,9 +48,11 @@ def __init__(
         token: Optional[str] = None,
         client_certs: Optional[Tuple[str, str]] = None,
         namespace: Optional[str] = None,
-        session: Optional[httpx.AsyncClient] = None,
+        session: Optional["httpx.AsyncClient"] = None,
     ) -> None:
         """AsyncEvents service constructor."""
+        import httpx
+
         self.host = cast(str, host or global_config.host)
         self.verify_ssl = verify_ssl if verify_ssl is not None else global_config.verify_ssl
         self.client_certs = client_certs if client_certs is not None else global_config.client_certs

src/hera/exceptions/__init__.py

@@ -6,11 +6,13 @@
 
 import json
 from http import HTTPStatus
-from typing import Dict, Type, Union
+from typing import TYPE_CHECKING, Dict, Type, Union
 
-import httpx
 from requests import Response
 
+if TYPE_CHECKING:
+    import httpx
+
 
 class HeraException(Exception):
     """Base class for exceptions in this module."""
@@ -76,7 +78,7 @@ def exception_from_status_code(status_code: int, msg: str) -> HeraException:
     return status_code_to_exception_map.get(status_code, HeraException)(msg)
 
 
-def exception_from_server_response(resp: Union[Response, httpx.Response]) -> HeraException:
+def exception_from_server_response(resp: Union[Response, "httpx.Response"]) -> HeraException:
     """Return a `HeraException` mapped from the given `Response`."""
     is_success = resp.ok if isinstance(resp, Response) else resp.is_success
     assert not is_success, "This function should only be called with non-2xx responses"

src/hera/workflows/async_service.py

@@ -2,11 +2,9 @@
 
 # [DO NOT MODIFY] Auto-generated by `hera/scripts/async_service.py`
 import os
-from typing import Optional, Tuple, cast
+from typing import TYPE_CHECKING, Optional, Tuple, cast
 from urllib.parse import urljoin
 
-import httpx
-
 from hera.exceptions import exception_from_server_response
 from hera.shared import global_config
 from hera.workflows.models import (
@@ -54,6 +52,9 @@
     WorkflowTerminateRequest,
 )
 
+if TYPE_CHECKING:
+    import httpx
+
 
 def valid_host_scheme(host: str) -> bool:
     """Validates the the given `host` starts with either `http` or `https`."""
@@ -70,9 +71,11 @@ def __init__(
         token: Optional[str] = None,
         client_certs: Optional[Tuple[str, str]] = None,
         namespace: Optional[str] = None,
-        session: Optional[httpx.AsyncClient] = None,
+        session: Optional["httpx.AsyncClient"] = None,
     ) -> None:
         """AsyncWorkflows service constructor."""
+        import httpx
+
         self.host = cast(str, host or global_config.host)
         self.verify_ssl = verify_ssl if verify_ssl is not None else global_config.verify_ssl
         self.client_certs = client_certs if client_certs is not None else global_config.client_certs