Fix incorrect timestamp parsing for chef-client.log in CloudWatch Agent

The CloudWatch Agent configuration was using the 'default' timestamp format
(%Y-%m-%d %H:%M:%S,%f) for chef-client.log, but Chef/Cinc outputs timestamps
in ISO 8601 format: [YYYY-MM-DDTHH:MM:SS+TZ].

This mismatch caused CloudWatch to fail parsing timestamps, resulting in log
lines being associated with incorrect timestamps (often shifted by hours),
which significantly complicated root cause analysis during incident
investigations.

Changes:
- Add new 'chef' timestamp format: [%Y-%m-%dT%H:%M:%S
  (Note: CloudWatch Agent's %z only supports timezone without colon like -0700,
  but Chef outputs +02:00 format. We match up to seconds and let CloudWatch
  handle the rest.)
- Update chef-client.log configuration to use the new 'chef' format

Reference: https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch-Agent-Configuration-File-Details.html\#CloudWatch-Agent-Configuration-File-Logssection

Author: hehe7318

CHANGELOG.md

@@ -25,6 +25,9 @@ This file is used to list changes made in each version of the AWS ParallelCluste
   - Rdma-core: rdma-core-59.0-1
   - Open MPI: openmpi40-aws-4.1.7-2 and openmpi50-aws-5.0.8-11
 
+**BUG FIXES**
+- Fix incorrect timestamp parsing for chef-client.log in CloudWatch Agent configuration. The timestamp format now correctly matches Chef's output format `[YYYY-MM-DDTHH:MM:SS+TZ]`.
+
 3.14.0
 ------
 

cookbooks/aws-parallelcluster-environment/files/cloudwatch/cloudwatch_agent_config.json

@@ -4,6 +4,7 @@
     "default": "%Y-%m-%d %H:%M:%S,%f",
     "bracket_default": "[%Y-%m-%d %H:%M:%S]",
     "slurm": "%Y-%m-%dT%H:%M:%S.%f",
+    "chef": "[%Y-%m-%dT%H:%M:%S",
     "json": ""
   },
   "log_configs": [
@@ -82,7 +83,7 @@
       "feature_conditions": []
     },
     {
-      "timestamp_format_key": "default",
+      "timestamp_format_key": "chef",
       "file_path": "/var/log/chef-client.log",
       "log_stream_name": "chef-client",
       "schedulers": [