fix: Apps running in Workbench will now have ws_per_message_deflate=False enforced

CHANGELOG.md

@@ -50,6 +50,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Bug fixes
 
+* Fixed issue where apps run in Workbench were unexpectedly crashing. Apps running in Workbench will now have `ws_per_message_deflate=False` enforced. (#2005)
+
 * Fixed an issue where the `<main>` areas of `ui.page_sidebar()` and `ui.page_navbar()` (with a `sidebar`) were made to be a fillable containers even when `fillable=False`. (#1816)
 
 * Fixed an issue where the `.update_user_input()` method on `ui.Chat()` isn't working in shinylive.  (#1891)

shiny/_main.py

@@ -9,6 +9,7 @@
 import re
 import sys
 import types
+import warnings
 from pathlib import Path
 from typing import Any, Optional
 
@@ -20,6 +21,7 @@
 
 from . import __version__, _autoreload, _hostenv, _static, _utils
 from ._docstring import no_example
+from ._hostenv import is_workbench
 from ._typing_extensions import NotRequired, TypedDict
 from .bookmark._bookmark_state import shiny_bookmarks_folder_name
 from .express import is_express_app
@@ -399,6 +401,8 @@ def run_app(
 
     maybe_setup_rsw_proxying(log_config)
 
+    _set_workbench_kwargs(kwargs)
+
     uvicorn.run(  # pyright: ignore[reportUnknownMemberType]
         app,
         host=host,
@@ -713,6 +717,18 @@ class ReloadArgs(TypedDict):
     reload_dirs: NotRequired[list[str]]
 
 
+def _set_workbench_kwargs(kwargs: dict[str, Any]) -> None:
+    if is_workbench():
+        if kwargs.get("ws_per_message_deflate"):
+            # Workaround for nginx/uvicorn issue within Workbench
+            # https://github.com/rstudio/rstudio-pro/issues/7368#issuecomment-2918016088
+            warnings.warn(
+                "Overwriting kwarg `ws_per_message_deflate=True` to `False` to avoid breaking issue in Workbench",
+                stacklevel=2,
+            )
+        kwargs["ws_per_message_deflate"] = False
+
+
 # Check that the version of rsconnect supports Shiny Express; can be removed in the
 # future once this version of rsconnect is widely used. The dependency on "packaging"
 # can also be removed then, because it is only used here. (Added 2024-03)

tests/pytest/test_main.py

@@ -0,0 +1,55 @@
+import os
+import warnings
+from typing import Any, Dict
+
+import pytest
+
+from shiny._main import _set_workbench_kwargs
+
+
+def test_workbench_kwargs_if_url_set():
+    """
+    Test that the `ws_per_message_deflate` kwarg is set to False when
+    RS_SERVER_URL and RS_SESSION_URL are set in the environment.
+    This is to avoid breaking issues in Workbench.
+    If the kwargs are set to True, a warning is raised and the value is set to False.
+    """
+    # Workbench URL is set, kwargs are not
+    os.environ["RS_SERVER_URL"] = "any_string"
+    os.environ["RS_SESSION_URL"] = "any_string"
+
+    kwargs: Dict[str, Any] = {}
+    _set_workbench_kwargs(kwargs)
+    assert kwargs.get("ws_per_message_deflate") is False
+
+    # kwarg have been set to True
+    kwargs = {
+        "ws_per_message_deflate": True,
+    }
+    with pytest.warns(UserWarning):
+        warnings.warn(
+            "Overwriting kwarg `ws_per_message_deflate=True` to `False` to avoid breaking issue in Workbench",
+            UserWarning,
+            stacklevel=2,
+        )
+        _set_workbench_kwargs(kwargs)
+        assert kwargs.get("ws_per_message_deflate") is False
+
+    # Teardown
+    del os.environ["RS_SERVER_URL"]
+    del os.environ["RS_SESSION_URL"]
+
+
+def test_workbench_kwargs_if_url_not_set():
+    """
+    Test that the `ws_per_message_deflate` kwarg is not changed if the RS_SERVER_URL and RS_SESSION_URL environment variables are not set.
+    """
+    kwargs: Dict[str, Any] = {
+        "ws_per_message_deflate": True,
+    }
+    _set_workbench_kwargs(kwargs)
+    assert kwargs.get("ws_per_message_deflate") is True
+
+    kwargs: Dict[str, Any] = {}
+    _set_workbench_kwargs(kwargs)
+    assert kwargs.get("ws_per_message_deflate") is None