Add RHEL 8 family cgroups v2 detection and enablement instructions

Detect RHEL 8, AlmaLinux 8, Rocky Linux 8, and CloudLinux 8 systems and provide
clear instructions when cgroups v2 needs manual enablement.

These systems have cgroups v2 backported to kernel 4.18 but it's disabled by
default. When detected without cgroups v2 enabled, the system now:

1. Detects RHEL 8 family by checking /etc/redhat-release
2. Verifies if cgroups v2 is mounted (checks 'mount' output for 'cgroup2')
3. If not enabled, logs detailed instructions:
   - grubby command to add kernel parameter
   - Reboot instruction
   - Verification command
   - Clear step-by-step guide

Changes:
- _check_rhel8_cgroups_v2(): New method for RHEL 8 family detection
- _ensure_cgroups_enabled(): Calls RHEL 8 check before general checks
- check_cgroup_support(): Returns RHEL 8 status in support dict
  - rhel8_family: bool (detected RHEL 8 family)
  - rhel8_needs_enablement: bool (cgroups v2 not mounted)
  - os_name: str (full OS name from release file)

OS Support Status:
✅ Ubuntu 20.04+ - Native cgroups v2 (kernel 5.4+)
✅ RHEL/Alma/Rocky 9+ - Native cgroups v2 (kernel 5.14+)
⚠️ RHEL/Alma/Rocky/CloudLinux 8 - Needs manual enable (kernel 4.18 backported)

plogical/resourceLimits.py

@@ -34,6 +34,91 @@ class ResourceLimitsManager:
         """Initialize the resource limits manager"""
         self._initialized = False
 
+    def _check_rhel8_cgroups_v2(self):
+        """
+        Check if RHEL 8 family needs manual cgroups v2 enablement
+
+        RHEL 8, AlmaLinux 8, Rocky Linux 8, and CloudLinux 8 have cgroups v2
+        backported to kernel 4.18 but it's disabled by default.
+
+        Returns:
+            bool: True if cgroups v2 is available or not RHEL 8, False if needs enablement
+        """
+        try:
+            # Check if this is a RHEL 8 family system
+            redhat_release_paths = ['/etc/redhat-release', '/etc/system-release']
+            is_rhel8 = False
+            os_name = "Unknown"
+
+            for release_file in redhat_release_paths:
+                if os.path.exists(release_file):
+                    try:
+                        with open(release_file, 'r') as f:
+                            release_content = f.read().lower()
+                            os_name = release_content.strip()
+
+                            # Check for RHEL 8 family (RHEL, AlmaLinux, Rocky, CloudLinux, CentOS 8)
+                            if ('release 8' in release_content or
+                                'release 8.' in release_content):
+                                if any(distro in release_content for distro in
+                                      ['red hat', 'almalinux', 'rocky', 'cloudlinux', 'centos']):
+                                    is_rhel8 = True
+                                    break
+                    except:
+                        pass
+
+            if not is_rhel8:
+                # Not RHEL 8 family, no special handling needed
+                return True
+
+            # This is RHEL 8 family - check if cgroups v2 is actually enabled
+            logging.writeToFile(f"Detected RHEL 8 family system: {os_name}")
+
+            # Check if cgroups v2 is mounted (indicates it's enabled)
+            try:
+                result = subprocess.run(
+                    ['mount'],
+                    capture_output=True,
+                    text=True,
+                    timeout=5
+                )
+
+                if 'cgroup2' in result.stdout:
+                    logging.writeToFile("cgroups v2 is enabled on RHEL 8 family system")
+                    return True
+                else:
+                    # cgroups v2 is not enabled - provide instructions
+                    logging.writeToFile("=" * 80)
+                    logging.writeToFile("RHEL 8 FAMILY: cgroups v2 MANUAL ENABLEMENT REQUIRED")
+                    logging.writeToFile("=" * 80)
+                    logging.writeToFile(f"System: {os_name}")
+                    logging.writeToFile(f"Kernel: {os.uname().release}")
+                    logging.writeToFile("")
+                    logging.writeToFile("RHEL 8, AlmaLinux 8, Rocky Linux 8, and CloudLinux 8 have cgroups v2")
+                    logging.writeToFile("backported but disabled by default. To enable, run these commands:")
+                    logging.writeToFile("")
+                    logging.writeToFile("1. Enable cgroups v2 in boot parameters:")
+                    logging.writeToFile("   grubby --update-kernel=ALL --args='systemd.unified_cgroup_hierarchy=1'")
+                    logging.writeToFile("")
+                    logging.writeToFile("2. Reboot the system:")
+                    logging.writeToFile("   reboot")
+                    logging.writeToFile("")
+                    logging.writeToFile("3. After reboot, verify cgroups v2 is enabled:")
+                    logging.writeToFile("   mount | grep cgroup2")
+                    logging.writeToFile("")
+                    logging.writeToFile("4. Then create websites with resource limits")
+                    logging.writeToFile("=" * 80)
+                    return False
+
+            except Exception as e:
+                logging.writeToFile(f"Error checking cgroups v2 mount status: {str(e)}")
+                return False
+
+        except Exception as e:
+            logging.writeToFile(f"Error checking RHEL 8 family status: {str(e)}")
+            # If we can't detect, assume it's OK and let the normal checks proceed
+            return True
+
     def _ensure_cgroups_enabled(self):
         """
         Ensure OpenLiteSpeed cgroups are enabled
@@ -46,9 +131,14 @@ class ResourceLimitsManager:
             return True
 
         try:
+            # Special check for RHEL 8 family systems
+            if not self._check_rhel8_cgroups_v2():
+                return False
+
             # Check kernel support first
             if not os.path.exists('/sys/fs/cgroup/cgroup.controllers'):
                 logging.writeToFile("cgroups v2 not available on this system (requires kernel 5.2+)")
+                logging.writeToFile("For RHEL 8 family, see instructions above to enable cgroups v2")
                 return False
 
             # Check if lscgctl exists
@@ -406,10 +496,38 @@ class ResourceLimitsManager:
             'memory_controller': False,
             'cpu_controller': False,
             'io_controller': False,
-            'quota_tools': False
+            'quota_tools': False,
+            'rhel8_family': False,
+            'rhel8_needs_enablement': False,
+            'os_name': 'Unknown'
         }
 
         try:
+            # Check for RHEL 8 family
+            redhat_release_paths = ['/etc/redhat-release', '/etc/system-release']
+            for release_file in redhat_release_paths:
+                if os.path.exists(release_file):
+                    try:
+                        with open(release_file, 'r') as f:
+                            release_content = f.read()
+                            support['os_name'] = release_content.strip()
+
+                            # Check for RHEL 8 family
+                            if ('release 8' in release_content.lower() or
+                                'release 8.' in release_content.lower()):
+                                if any(distro in release_content.lower() for distro in
+                                      ['red hat', 'almalinux', 'rocky', 'cloudlinux', 'centos']):
+                                    support['rhel8_family'] = True
+
+                                    # Check if cgroups v2 is actually mounted
+                                    result = subprocess.run(['mount'], capture_output=True,
+                                                          text=True, timeout=5)
+                                    if 'cgroup2' not in result.stdout:
+                                        support['rhel8_needs_enablement'] = True
+                                    break
+                    except:
+                        pass
+
             # Check cgroups v2
             if os.path.exists('/sys/fs/cgroup/cgroup.controllers'):
                 support['cgroups_v2'] = True