Merge "Add logging for config load source in verbose mode" into main

Author: zzzeek

alembic/config.py

@@ -4,6 +4,7 @@
 from argparse import Namespace
 from configparser import ConfigParser
 import inspect
+import logging
 import os
 from pathlib import Path
 import re
@@ -28,6 +29,9 @@
 from .util.pyfiles import _preserving_path_as_str
 
 
+log = logging.getLogger(__name__)
+
+
 class Config:
     r"""Represent an Alembic configuration.
 
@@ -244,10 +248,20 @@ def file_config(self) -> ConfigParser:
             here = Path()
         self.config_args["here"] = here.as_posix()
         file_config = ConfigParser(self.config_args)
+
+        verbose = getattr(self.cmd_opts, "verbose", False)
         if self._config_file_path:
             compat.read_config_parser(file_config, [self._config_file_path])
+            if verbose:
+                log.info(
+                    "Loading config from file: %s", self._config_file_path
+                )
         else:
             file_config.add_section(self.config_ini_section)
+            if verbose:
+                log.info(
+                    "No config file provided; using in-memory default config"
+                )
         return file_config
 
     @util.memoized_property

alembic/testing/env.py

@@ -1,4 +1,5 @@
 import importlib.machinery
+import logging
 import os
 from pathlib import Path
 import shutil
@@ -22,7 +23,29 @@ def _get_staging_directory():
         return "scratch"
 
 
+_restore_log = None
+
+
+def _replace_logger():
+    global _restore_log
+    if _restore_log is None:
+        _restore_log = (logging.root, logging.Logger.manager)
+        logging.root = logging.RootLogger(logging.WARNING)
+        logging.Logger.root = logging.root
+        logging.Logger.manager = logging.Manager(logging.root)
+
+
+def _restore_logger():
+    global _restore_log
+
+    if _restore_log is not None:
+        logging.root, logging.Logger.manager = _restore_log
+        logging.Logger.root = logging.root
+        _restore_log = None
+
+
 def staging_env(create=True, template="generic", sourceless=False):
+    _replace_logger()
     cfg = _testing_config()
     if create:
         path = _join_path(_get_staging_directory(), "scripts")
@@ -61,6 +84,7 @@ def clear_staging_env():
 
     engines.testing_reaper.close_all()
     shutil.rmtree(_get_staging_directory(), True)
+    _restore_logger()
 
 
 def script_file_fixture(txt):

docs/build/unreleased/1737.rst

@@ -0,0 +1,6 @@
+.. change::
+    :tags: feature, operations
+    :tickets: 1737
+
+    When alembic is run in "verbose" mode, alembic now logs a message to
+    indicate from which file is used to load the configuration.

tests/test_config.py

@@ -1,3 +1,5 @@
+import io
+import logging
 import os
 import pathlib
 import sys
@@ -45,6 +47,66 @@ def tearDown(self):
 
 
 class ConfigTest(TestBase):
+    def test_config_logging_with_file(self):
+        buf = io.StringIO()
+        handler = logging.StreamHandler(buf)
+        handler.setLevel(logging.INFO)
+
+        logger = logging.getLogger("alembic.config")
+        # logger.x=True
+        with (
+            mock.patch.object(logger, "handlers", []),
+            mock.patch.object(logger, "level", logging.NOTSET),
+        ):
+            logger.addHandler(handler)
+            logger.setLevel(logging.INFO)
+
+            cfg = _write_config_file(
+                """
+[alembic]
+script_location = %(base_path)s/db/migrations
+"""
+            )
+            test_cfg = config.Config(
+                cfg.config_file_name, config_args=dict(base_path="/tmp")
+            )
+            test_cfg.cmd_opts = mock.Mock(verbose=True)
+
+            _ = test_cfg.file_config
+
+            output = buf.getvalue()
+            assert "Loading config from file" in output
+            assert cfg.config_file_name.replace("/", os.path.sep) in output
+
+    def tearDown(self):
+        clear_staging_env()
+
+    def test_config_logging_without_file(self):
+        buf = io.StringIO()
+        handler = logging.StreamHandler(buf)
+        handler.setLevel(logging.INFO)
+
+        logger = logging.getLogger("alembic.config")
+        with (
+            mock.patch.object(logger, "handlers", []),
+            mock.patch.object(logger, "level", logging.NOTSET),
+        ):
+
+            logger.addHandler(handler)
+            logger.setLevel(logging.INFO)
+
+            test_cfg = config.Config()
+            test_cfg.cmd_opts = mock.Mock(verbose=True)
+
+            _ = test_cfg.file_config
+
+            output = buf.getvalue()
+            assert "No config file provided" in output
+            assert (
+                test_cfg.config_file_name is None
+                and test_cfg._config_file_path is None
+            )
+
     def test_config_no_file_main_option(self):
         cfg = config.Config()
         cfg.set_main_option("url", "postgresql://foo/bar")