Cleanup parsing_pre_import_modules setting

airflow-core/newsfragments/49839.misc.rst

@@ -0,0 +1,3 @@
+The ``parsing_pre_import_modules`` setting is removed from code base.
+It has no use in Airflow 3.
+If your deployment override this setting you can safely remove it.

airflow-core/src/airflow/config_templates/config.yml

@@ -2199,16 +2199,6 @@ scheduler:
       type: integer
       default: "20"
       see_also: ":ref:`scheduler:ha:tunables`"
-    parsing_pre_import_modules:
-      description: |
-        The scheduler reads dag files to extract the airflow modules that are going to be used,
-        and imports them ahead of time to avoid having to re-do it for each parsing process.
-        This flag can be set to ``False`` to disable this behavior in case an airflow module needs
-        to be freshly imported each time (at the cost of increased DAG parsing time).
-      version_added: 2.6.0
-      type: boolean
-      example: ~
-      default: "True"
     dag_stale_not_seen_duration:
       description: |
         Time in seconds after which dags, which were not updated by Dag Processor are deactivated.

airflow-core/src/airflow/utils/file.py

@@ -17,7 +17,6 @@
 # under the License.
 from __future__ import annotations
 
-import ast
 import hashlib
 import logging
 import os
@@ -323,26 +322,6 @@ def might_contain_dag_via_default_heuristic(file_path: str, zip_file: zipfile.Zi
     return any(s in content for s in (b"dag", b"asset"))
 
 
-def _find_imported_modules(module: ast.Module) -> Generator[str, None, None]:
-    for st in module.body:
-        if isinstance(st, ast.Import):
-            for n in st.names:
-                yield n.name
-        elif isinstance(st, ast.ImportFrom) and st.module is not None:
-            yield st.module
-
-
-def iter_airflow_imports(file_path: str) -> Generator[str, None, None]:
-    """Find Airflow modules imported in the given file."""
-    try:
-        parsed = ast.parse(Path(file_path).read_bytes())
-    except Exception:
-        return
-    for m in _find_imported_modules(parsed):
-        if m.startswith("airflow."):
-            yield m
-
-
 def get_unique_dag_module_name(file_path: str) -> str:
     """Return a unique module name in the format unusual_prefix_{sha1 of module's file path}_{original module name}."""
     if isinstance(file_path, str):

airflow-core/tests/unit/utils/test_file.py

@@ -193,24 +193,6 @@ def test_might_contain_dag(self):
         # With safe_mode is False, the user defined callable won't be invoked
         assert file_utils.might_contain_dag(file_path=file_path_with_dag, safe_mode=False)
 
-    def test_get_modules(self):
-        file_path = os.path.join(TEST_DAGS_FOLDER, "test_imports.py")
-
-        modules = list(file_utils.iter_airflow_imports(file_path))
-
-        assert len(modules) == 4
-        assert "airflow.utils" in modules
-        assert "airflow.decorators" in modules
-        assert "airflow.models" in modules
-        assert "airflow.sensors" in modules
-        # this one is a local import, we don't want it.
-        assert "airflow.local_import" not in modules
-        # this one is in a comment, we don't want it
-        assert "airflow.in_comment" not in modules
-        # we don't want imports under conditions
-        assert "airflow.if_branch" not in modules
-        assert "airflow.else_branch" not in modules
-
     def test_get_modules_from_invalid_file(self):
         file_path = os.path.join(TEST_DAGS_FOLDER, "README.md")  # just getting a non-python file
 
@@ -233,7 +215,6 @@ def test_list_py_file_paths(self, test_zip_path):
             "test_invalid_param3.py",
             "test_invalid_param4.py",
             "test_nested_dag.py",
-            "test_imports.py",
             "file_no_airflow_dag.py",  # no_dag test case in test_zip folder
             "test.py",  # no_dag test case in test_zip_module folder
             "__init__.py",