Remove usage of temporary file to read computemgtd config

CHANGELOG.md

@@ -19,6 +19,7 @@ This file is used to list changes made in each version of the aws-parallelcluste
 
 **BUG FIXES**
 - Handle corner case in the scaling logic when instance is just launched and the describe instances API doesn't report yet all the EC2 info.
+- Fix file handle leak in `computemgtd`.
 
 3.1.4
 ------

src/slurm_plugin/computemgtd.py

@@ -15,14 +15,14 @@
 import time
 from configparser import ConfigParser
 from datetime import datetime, timezone
+from io import StringIO
 from logging.config import fileConfig
 from subprocess import CalledProcessError
-from tempfile import NamedTemporaryFile
 
 from botocore.config import Config
 from common.schedulers.slurm_commands import get_nodes_info
 from common.time_utils import seconds
-from common.utils import run_command, sleep_remaining_loop_time
+from common.utils import check_command_output, run_command, sleep_remaining_loop_time
 from retrying import retry
 from slurm_plugin.common import (
     DEFAULT_COMMAND_TIMEOUT,
@@ -55,8 +55,6 @@ class ComputemgtdConfig:
     }
 
     def __init__(self, config_file_path):
-        tf = NamedTemporaryFile()
-        self._local_config_file = tf.name
         self._get_config(config_file_path)
 
     def __repr__(self):
@@ -70,12 +68,12 @@ def _get_config(self, config_file_path):
         config = ConfigParser()
         try:
             # Use subprocess based method to copy shared file to local to prevent hanging when NFS is down
-            run_command(
-                f"cat {config_file_path} > {self._local_config_file}",
+            config_str = check_command_output(
+                f"cat {config_file_path}",
                 timeout=DEFAULT_COMMAND_TIMEOUT,
                 shell=True,  # nosec
             )
-            config.read_file(open(self._local_config_file, "r"))
+            config.read_file(StringIO(config_str))
         except Exception:
             log.error(f"Cannot read computemgtd configuration file: {config_file_path}")
             raise

tests/slurm_plugin/test_computemgtd.py

@@ -62,8 +62,7 @@
 )
 def test_computemgtd_config(config_file, expected_attributes, test_datadir, mocker):
     mocker.patch("slurm_plugin.computemgtd.ComputemgtdConfig._read_nodename_from_file", return_value="some_nodename")
-    mocker.patch("slurm_plugin.computemgtd.run_command")
-    mocker.patch("slurm_plugin.computemgtd.open", return_value=open(test_datadir / config_file, "r"))
+    mocker.patch("slurm_plugin.computemgtd.check_command_output", return_value=(test_datadir / config_file).read_text())
     compute_config = ComputemgtdConfig("mocked_config_path")
     for key in expected_attributes:
         assert_that(compute_config.__dict__.get(key)).is_equal_to(expected_attributes.get(key))