[PATCH 1/3] rteval: Add container detection module

Add a new containercheck module to detect if rteval is running inside
a container. The module checks multiple indicators:

- Presence of /.dockerenv file (Docker)
- /proc/1/cgroup patterns (docker, lxc, kubepods, libpod)
- Container-related environment variables
- Kubernetes environment indicators
- systemd-detect-virt utility if available

The module includes a unit_test() function for standalone testing,
following the pattern used by other sysinfo modules.

Assisted-by: Claude:claude-sonnet-4-5
Signed-off-by: John Kacur <[email protected]>
---
 rteval/sysinfo/containercheck.py | 68 ++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 rteval/sysinfo/containercheck.py

diff --git a/rteval/sysinfo/containercheck.py b/rteval/sysinfo/containercheck.py
new file mode 100644
index 000000000000..c558ee05dd8c
--- /dev/null
+++ b/rteval/sysinfo/containercheck.py
@@ -0,0 +1,68 @@
+# -*- coding: utf-8 -*-
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+#   Copyright 2026 - John Kacur <[email protected]>
+#
+"""Module for detecting if rteval is running in a container"""
+
+import os
+import re
+import subprocess
+
+
+def is_container():
+    """
+    Detect if running in a container (comprehensive check).
+
+    Returns:
+        bool: True if running in a container, False otherwise
+    """
+
+    # Check 1: .dockerenv file
+    if os.path.exists('/.dockerenv'):
+        return True
+
+    # Check 2: /proc/1/cgroup
+    try:
+        with open('/proc/1/cgroup', 'r') as f:
+            if re.search(r'docker|lxc|kubepods|libpod', f.read()):
+                return True
+    except (FileNotFoundError, PermissionError):
+        pass
+
+    # Check 3: Environment variables
+    if os.environ.get('container'):
+        return True
+
+    # Check 4: Kubernetes
+    if os.environ.get('KUBERNETES_SERVICE_HOST'):
+        return True
+
+    # Check 5: systemd-detect-virt (if available)
+    try:
+        result = subprocess.run(
+            ['systemd-detect-virt', '-c'],
+            capture_output=True,
+            text=True,
+            timeout=1
+        )
+        if result.returncode == 0:
+            return True
+    except (FileNotFoundError, subprocess.TimeoutExpired):
+        pass
+
+    return False
+
+
+def unit_test(rootdir):
+    """Simple test of container detection"""
+    result = is_container()
+    print(f"Container detection result: {result}")
+    if result:
+        print("Running in a container")
+    else:
+        print("Not running in a container")
+
+
+if __name__ == '__main__':
+    unit_test(None)
-- 
2.54.0