Support passing through all modules (#737)

Fixes #691

README.md

@@ -1029,6 +1029,21 @@ my_worker = Worker(
 In both of these cases, now the `pydantic` module will be passed through from outside of the sandbox instead of
 being reloaded for every workflow run.
 
+If users are sure that no imports they use in workflow files will ever need to be sandboxed (meaning all calls within
+are deterministic and never mutate shared, global state), the `passthrough_all_modules` option can be set on the
+restrictions or the `with_passthrough_all_modules` helper can by used, for example:
+
+```python
+my_worker = Worker(
+  ...,
+  workflow_runner=SandboxedWorkflowRunner(
+    restrictions=SandboxRestrictions.default.with_passthrough_all_modules()
+  )
+)
+```
+
+Note, some calls from the module may still be checked for invalid calls at runtime for certain builtins.
+
 ###### Invalid Module Members
 
 `SandboxRestrictions.invalid_module_members` contains a root matcher that applies to all module members. This already

temporalio/worker/workflow_sandbox/_importer.py

@@ -252,10 +252,11 @@ def _assert_valid_module(self, name: str) -> None:
             raise RestrictedWorkflowAccessError(name)
 
     def _maybe_passthrough_module(self, name: str) -> Optional[types.ModuleType]:
-        # If imports not passed through and name not in passthrough modules,
-        # check parents
+        # If imports not passed through and all modules are not passed through
+        # and name not in passthrough modules, check parents
         if (
             not temporalio.workflow.unsafe.is_imports_passed_through()
+            and not self.restrictions.passthrough_all_modules
             and name not in self.restrictions.passthrough_modules
         ):
             end_dot = -1

temporalio/worker/workflow_sandbox/_restrictions.py

@@ -99,6 +99,17 @@ class methods (including __init__, etc). The check compares the against the
     fully qualified path to the item.
     """
 
+    passthrough_all_modules: bool = False
+    """
+    Pass through all modules, do not sandbox any modules. This is the equivalent
+    of setting :py:attr:`passthrough_modules` to a list of all modules imported
+    by the workflow. This is unsafe. This means modules are never reloaded per
+    workflow run which means workflow authors have to be careful that they don't
+    import modules that do non-deterministic things. Note, just because a module
+    is passed through from outside the sandbox doesn't mean runtime restrictions
+    on invalid calls are not still applied.
+    """
+
     passthrough_modules_minimum: ClassVar[Set[str]]
     """Set of modules that must be passed through at the minimum."""
 
@@ -133,6 +144,12 @@ def with_passthrough_modules(self, *modules: str) -> SandboxRestrictions:
             self, passthrough_modules=self.passthrough_modules | set(modules)
         )
 
+    def with_passthrough_all_modules(self) -> SandboxRestrictions:
+        """Create a new restriction set with :py:attr:`passthrough_all_modules`
+        as true.
+        """
+        return dataclasses.replace(self, passthrough_all_modules=True)
+
 
 # We intentionally use specific fields instead of generic "matcher" callbacks
 # for optimization reasons.

tests/worker/workflow_sandbox/test_importer.py

@@ -64,6 +64,22 @@ def test_workflow_sandbox_importer_passthough_context_manager():
     assert id(outside) == id(inside)
 
 
+def test_workflow_sandbox_importer_passthrough_all_modules():
+    import tests.worker.workflow_sandbox.testmodules.stateful_module as outside
+
+    # Confirm regular restrictions does re-import
+    with Importer(restrictions, RestrictionContext()).applied():
+        import tests.worker.workflow_sandbox.testmodules.stateful_module as inside1
+    assert id(outside) != id(inside1)
+
+    # But that one with all modules passed through does not
+    with Importer(
+        restrictions.with_passthrough_all_modules(), RestrictionContext()
+    ).applied():
+        import tests.worker.workflow_sandbox.testmodules.stateful_module as inside2
+    assert id(outside) == id(inside2)
+
+
 def test_workflow_sandbox_importer_invalid_module_members():
     importer = Importer(restrictions, RestrictionContext())
     # Can access the function, no problem