Added support for a FLASK_RUN_EXTRA_FILES config variable.

Similar to the `flask run --extra_files=..` CLI argument or the `FLASK_RUN_EXTRA_FILES` environment variable, this is another method to specify other files to watch.

docs/cli.rst

@@ -184,12 +184,16 @@ reloader.
 Watch Extra Files with the Reloader
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+.. versionadded:: 2.1
+  Support for the ``FLASK_RUN_EXTRA_FILES`` config variable was added.
+
 When using development mode, the reloader will trigger whenever your
 Python code or imported modules change. The reloader can watch
 additional files with the ``--extra-files`` option, or the
 ``FLASK_RUN_EXTRA_FILES`` environment variable. Multiple paths are
 separated with ``:``, or ``;`` on Windows.
 
+
 .. tabs::
 
    .. group-tab:: Bash
@@ -226,6 +230,15 @@ separated with ``:``, or ``;`` on Windows.
            * Detected change in '/path/to/file1', reloading
 
 
+Alternatively, you can set the ``FLASK_RUN_EXTRA_FILES`` config
+variable, which takes a list of files::
+  from flask import Flask
+
+  app = Flask(__name__)
+  app.config['FLASK_RUN_EXTRA_FILES'] = ["file1", "dirA/file2", "dirB/"]
+
+
+
 Debug Mode
 ----------
 

src/flask/app.py

@@ -914,6 +914,7 @@ class Flask(Scaffold):
         options.setdefault("use_reloader", self.debug)
         options.setdefault("use_debugger", self.debug)
         options.setdefault("threaded", True)
+        options.setdefault("extra_files", self.config.get("FLASK_RUN_EXTRA_FILES"))
 
         cli.show_server_banner(self.env, self.debug, self.name, False)
 

src/flask/cli.py

@@ -841,6 +841,11 @@ def run_command(
     if debugger is None:
         debugger = debug
 
+    # Override extra_files argument with config variable if specified
+    app = info.load_app()
+    if app.config.get("FLASK_RUN_EXTRA_FILES"):
+        extra_files = app.config.get("FLASK_RUN_EXTRA_FILES")
+
     show_server_banner(get_env(), debug, info.app_import_path, eager_loading)
     app = DispatchingApp(info.load_app, use_eager_loading=eager_loading)