feat(local): add --no-watch flag to disable hot reload

samcli/lib/utils/file_observer.py

@@ -3,6 +3,7 @@
 """
 
 import logging
+import os
 import platform
 import threading
 import uuid
@@ -183,11 +184,15 @@ def _on_change(self, resources: List[str], package_type: str) -> None:
         package_type: str
             determine if the changed resource is a source code path or an image name
         """
+        LOG.debug("Acquiring lock for _on_change to process %s %s resource changes: %s", 
+                 len(resources), package_type, resources)
         with self._watch_lock:
             changed_functions: List[FunctionConfig] = []
             for resource in resources:
                 if self._observed_functions[package_type].get(resource, None):
                     changed_functions += self._observed_functions[package_type][resource]
+            LOG.debug("Acquired lock and processing %s changed functions from %s resources", 
+                     len(changed_functions), len(resources))
             self._input_on_change(changed_functions)
 
     def watch(self, function_config: FunctionConfig) -> None:
@@ -204,9 +209,13 @@ def watch(self, function_config: FunctionConfig) -> None:
         ObserverException:
             if not able to observe the input function source path/image
         """
+        LOG.debug("Acquiring lock for watch to observe %s function: %s", 
+                 function_config.packagetype, function_config.name)
         with self._watch_lock:
             if self.get_resources.get(function_config.packagetype, None):
                 resources = self.get_resources[function_config.packagetype](function_config)
+                LOG.debug("Acquired lock for watch, observing %s resources for function %s: %s", 
+                         len(resources), function_config.name, resources)
                 for resource in resources:
                     functions = self._observed_functions[function_config.packagetype].get(resource, [])
                     functions += [function_config]
@@ -415,6 +424,17 @@ class SingletonFileObserver(metaclass=Singleton):
     A Singleton class that will observe some file system paths for any change for multiple purposes.
     """
 
+    # Ignore patterns for file watching to avoid infinite loops and unnecessary events
+    DEFAULT_IGNORE_PATTERNS = [
+        "*/node_modules/*/*",  # Ignore changes within packages, but allow new packages
+        "*.tmp",               # Ignore temporary files
+        "*.temp",              # Ignore temporary files
+        "*/.git/*",            # Ignore git directories
+        "*/__pycache__/*",     # Ignore Python cache
+        "*.pyc",               # Ignore Python compiled files
+        "*.log"                # Ignore log files
+    ]
+
     def __init__(self) -> None:
         """
         Initialize the file observer
@@ -424,12 +444,22 @@ def __init__(self) -> None:
         self._observed_watches: Dict[str, ObservedWatch] = {}
         self._watch_dog_observed_paths: Dict[str, List[str]] = {}
         self._observer: BaseObserver = Observer()
+
+        # Use environment variable to control ignore patterns (default: enabled)
+        use_ignore_patterns = os.environ.get("SAM_USE_IGNORE_PATTERN", "true").lower() == "true"
+        ignore_patterns = self.DEFAULT_IGNORE_PATTERNS if use_ignore_patterns else []
+
+        if use_ignore_patterns:
+            LOG.debug("File observer using ignore patterns: %s", ignore_patterns)
+        else:
+            LOG.debug("File observer ignore patterns disabled via SAM_CLI_FILE_OBSERVER_IGNORE_PATTERNS")
+
         self._code_modification_handler: PatternMatchingEventHandler = PatternMatchingEventHandler(
-            patterns=["*"], ignore_patterns=[], ignore_directories=False
+            patterns=["*"], ignore_patterns=ignore_patterns, ignore_directories=False
         )
 
         self._code_deletion_handler: PatternMatchingEventHandler = PatternMatchingEventHandler(
-            patterns=["*"], ignore_patterns=[], ignore_directories=False
+            patterns=["*"], ignore_patterns=ignore_patterns, ignore_directories=False
         )
 
         self._code_modification_handler.on_modified = self.on_change  # type: ignore