Allow storing test metrics in local filesystem of LocalStack container (#13188)

nik-localstack · web-flow · commit 343d43640fd5 · 2025-10-13T09:20:14.000+03:00
diff --git a/localstack-core/localstack/aws/handlers/metric_handler.py b/localstack-core/localstack/aws/handlers/metric_handler.py
@@ -1,9 +1,15 @@
+import csv
 import logging
+import os
+from datetime import datetime
+from pathlib import Path
 
 from localstack import config
 from localstack.aws.api import RequestContext
 from localstack.aws.chain import HandlerChain
+from localstack.constants import ENV_INTERNAL_TEST_STORE_METRICS_PATH
 from localstack.http import Response
+from localstack.utils.strings import short_uid
 
 LOG = logging.getLogger(__name__)
 
@@ -137,6 +143,32 @@ class MetricHandler:
 
     def __init__(self) -> None:
         self.metrics_handler_items = {}
+        self.local_filename = None
+
+        if self.should_store_metric_locally():
+            self.local_filename = self.create_local_file()
+
+    @staticmethod
+    def should_store_metric_locally() -> bool:
+        return config.is_collect_metrics_mode() and config.store_test_metrics_in_local_filesystem()
+
+    @staticmethod
+    def create_local_file():
+        folder = Path(
+            os.environ.get(ENV_INTERNAL_TEST_STORE_METRICS_PATH, "/tmp/localstack-metrics")
+        )
+        if not folder.exists():
+            folder.mkdir(parents=True, exist_ok=True)
+        LOG.debug("Metric reports will be stored in %s", folder)
+        filename = (
+            folder
+            / f"metric-report-raw-data-{datetime.utcnow().strftime('%Y-%m-%d__%H_%M_%S')}-{short_uid()}.csv"
+        )
+        with open(filename, "w") as fd:
+            LOG.debug("Creating new metric data file %s", filename)
+            writer = csv.writer(fd)
+            writer.writerow(Metric.RAW_DATA_HEADER)
+        return filename
 
     def create_metric_handler_item(
         self, chain: HandlerChain, context: RequestContext, response: Response
@@ -194,7 +226,15 @@ def update_metric_collection(
         )
         # refrain from adding duplicates
         if metric not in MetricHandler.metric_data:
-            MetricHandler.metric_data.append(metric)
+            self.append_metric(metric)
 
         # cleanup
         del self.metrics_handler_items[context]
+
+    def append_metric(self, metric: Metric):
+        if self.should_store_metric_locally():
+            with open(self.local_filename, "a") as fd:
+                writer = csv.writer(fd)
+                writer.writerow(metric)
+        else:
+            MetricHandler.metric_data.append(metric)
diff --git a/localstack-core/localstack/config.py b/localstack-core/localstack/config.py
@@ -19,6 +19,7 @@
     DEFAULT_VOLUME_DIR,
     ENV_INTERNAL_TEST_COLLECT_METRIC,
     ENV_INTERNAL_TEST_RUN,
+    ENV_INTERNAL_TEST_STORE_METRICS_IN_LOCALSTACK,
     FALSE_STRINGS,
     LOCALHOST,
     LOCALHOST_IP,
@@ -1451,6 +1452,11 @@ def is_collect_metrics_mode() -> bool:
     return is_env_true(ENV_INTERNAL_TEST_COLLECT_METRIC)
 
 
+def store_test_metrics_in_local_filesystem() -> bool:
+    """Returns True if test metrics should be stored in the local filesystem (instead of the system that runs pytest)."""
+    return is_env_true(ENV_INTERNAL_TEST_STORE_METRICS_IN_LOCALSTACK)
+
+
 def collect_config_items() -> list[tuple[str, Any]]:
     """Returns a list of key-value tuples of LocalStack configuration values."""
     none = object()  # sentinel object
diff --git a/localstack-core/localstack/constants.py b/localstack-core/localstack/constants.py
@@ -80,6 +80,10 @@
 # environment variable name to tag collect metrics during a test run
 ENV_INTERNAL_TEST_COLLECT_METRIC = "LOCALSTACK_INTERNAL_TEST_COLLECT_METRIC"
 
+# environment variable name to indicate that metrics should be stored within the container
+ENV_INTERNAL_TEST_STORE_METRICS_IN_LOCALSTACK = "LOCALSTACK_INTERNAL_TEST_METRICS_IN_LOCALSTACK"
+ENV_INTERNAL_TEST_STORE_METRICS_PATH = "LOCALSTACK_INTERNAL_TEST_STORE_METRICS_PATH"
+
 # environment variable that flags whether pro was activated. do not use it for security purposes!
 ENV_PRO_ACTIVATED = "PRO_ACTIVATED"
 
