backend start script: check ulimit and increase soft limit if possible

src/start_fact_backend.py

@@ -20,6 +20,7 @@
 import grp
 import logging
 import os
+import resource
 import sys
 from pathlib import Path
 
@@ -37,6 +38,8 @@
 from scheduler.unpacking_scheduler import UnpackingScheduler
 from storage.unpacking_locks import UnpackingLockManager
 
+ULIMIT_MIN = 2048
+
 
 class FactBackend(FactBase):
     PROGRAM_NAME = 'FACT Backend'
@@ -47,6 +50,7 @@ def __init__(self):
         super().__init__()
         self.unpacking_lock_manager = UnpackingLockManager()
         self._create_docker_base_dir()
+        _check_ulimit()
 
         try:
             self.analysis_service = AnalysisScheduler(unpacking_locks=self.unpacking_lock_manager)
@@ -110,6 +114,20 @@ def _exception_occurred(self):
         )
 
 
+def _check_ulimit():
+    soft_limit, hard_limit = resource.getrlimit(resource.RLIMIT_NOFILE)
+    if hard_limit < ULIMIT_MIN:
+        logging.critical(
+            f'The open file limit must be set to at least {ULIMIT_MIN} (ideally 10000 or more, depending on the '
+            'number of worker processes) so that the backend of FACT can work without errors. Please increase the '
+            'open file limit (e.g. by running `ulimit -n 9999` in this shell before starting FACT).'
+        )
+        sys.exit(1)
+    if soft_limit < hard_limit:
+        # we are only allowed to increase the soft limit and not the hard limit
+        resource.setrlimit(resource.RLIMIT_NOFILE, (hard_limit, hard_limit))
+
+
 if __name__ == '__main__':
     FactBackend().main()
     sys.exit(0)