# Enhanced VM Watchdog Script for Unraid: Automatic Crash Recovery with Logging and Error Handling

**URL:** <https://forum.hhf.technology/t/enhanced-vm-watchdog-script-for-unraid-automatic-crash-recovery-with-logging-and-error-handling/402>\
**Category:** Home Servers\
**Tags:** unraid, scripts, vm-watchdog-script\
**Created:** [November 16, 2024, 7:36am UTC](https://forum.hhf.technology/t/enhanced-vm-watchdog-script-for-unraid-automatic-crash-recovery-with-logging-and-error-handling/402 "2024-11-16T07:36:20Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![hhf.technoloy](https://forum.hhf.technology/user_avatar/forum.hhf.technology/hhf.technoloy/32/68_2.png) [@hhf.technoloy](https://forum.hhf.technology/u/hhf.technoloy)\
**Post date:** [November 16, 2024, 7:36am UTC](https://forum.hhf.technology/t/enhanced-vm-watchdog-script-for-unraid-automatic-crash-recovery-with-logging-and-error-handling/402/1 "2024-11-16T07:36:20Z")

</div>

I’ve enhanced the script with several important improvements:

1. **Error Handling** :

2. **Logging** :

3. **Process Management** :

4. **Configuration** :

5. **Code Structure** :

To use this script:

1. Install User Scripts plugin from Community Apps
2. Navigate to Settings \> User Utilities \> User Scripts
3. Create a new script and paste this code
4. Modify the configuration variables at the top as needed:
  - `VM_NAME`: Name of your VM
  - `MAX_RESTART_ATTEMPTS`: Maximum number of restart attempts
  - `RESTART_COOLDOWN`: Time to wait between restart attempts
  - `LOG_FILE`: Location of the log file

5. Set up the schedule using cron notation (e.g., `*/3 * * * *` for every 3 minutes)

The script will now:

- Check if the VM exists before attempting any operations
- Try to restart the VM multiple times if it fails
- Wait between attempts to avoid rapid cycling
- Log all actions with timestamps
- Prevent multiple instances from running simultaneously
- Clean up after itself properly

You can monitor the script’s activity by checking the log file at `/boot/logs/vm_watchdog.log`.

```bash
#!/bin/bash

# ===========================================
# Unraid VM Watchdog Script
# This script monitors and automatically restarts specified VMs if they crash
# ===========================================

# Configuration
readonly VM_NAME="Windows 11" # Name of the VM to monitor
readonly MAX_RESTART_ATTEMPTS=3 # Maximum number of restart attempts
readonly RESTART_COOLDOWN=300 # Cooldown period between restarts (in seconds)
readonly LOG_FILE="/boot/logs/vm_watchdog.log" # Log file location
readonly LOCK_FILE="/tmp/vm_watchdog.lock" # Lock file to prevent multiple instances

# Function to log messages with timestamps
log_message() {
    local message="$1"
    local timestamp=$(date '+%Y-%m-%d %H:%M:%S')
    echo "[$timestamp] $message" >> "$LOG_FILE"
    echo "[$timestamp] $message"
}

# Function to check if another instance is running
check_lock() {
    if [-f "$LOCK_FILE"]; then
        pid=$(cat "$LOCK_FILE")
        if ps -p "$pid" > /dev/null 2>&1; then
            log_message "Another instance is already running (PID: $pid)"
            exit 1
        else
            # Clean up stale lock file
            rm -f "$LOCK_FILE"
        fi
    fi
    echo $$ > "$LOCK_FILE"
}

# Function to clean up lock file
cleanup() {
    rm -f "$LOCK_FILE"
    log_message "Script execution completed"
}

# Set up trap for cleanup
trap cleanup EXIT

# Function to get VM state
get_vm_state() {
    virsh list --all | grep -w "$VM_NAME" | awk '{print $NF}'
}

# Function to check if VM exists
check_vm_exists() {
    if ! virsh list --all | grep -q "$VM_NAME"; then
        log_message "ERROR: VM '$VM_NAME' not found"
        exit 1
    fi
}

# Function to attempt VM restart
restart_vm() {
    local attempt=$1
    log_message "Attempting to start VM '$VM_NAME' (Attempt $attempt of $MAX_RESTART_ATTEMPTS)"
    
    if virsh start "$VM_NAME"; then
        log_message "Successfully started VM '$VM_NAME'"
        return 0
    else
        log_message "Failed to start VM '$VM_NAME'"
        return 1
    fi
}

# Main script execution
main() {
    # Create log directory if it doesn't exist
    mkdir -p "$(dirname "$LOG_FILE")"
    
    # Check for lock file
    check_lock
    
    # Verify VM exists
    check_vm_exists
    
    # Get current VM state
    local state=$(get_vm_state)
    
    if ["$state" != "running"]; then
        log_message "VM '$VM_NAME' is not running (Current state: $state)"
        
        # Attempt to restart the VM with retry logic
        for attempt in $(seq 1 $MAX_RESTART_ATTEMPTS); do
            if restart_vm "$attempt"; then
                exit 0
            fi
            
            if ["$attempt" -lt "$MAX_RESTART_ATTEMPTS"]; then
                log_message "Waiting $RESTART_COOLDOWN seconds before next attempt..."
                sleep "$RESTART_COOLDOWN"
            fi
        done
        
        if ["$attempt" -eq "$MAX_RESTART_ATTEMPTS"]; then
            log_message "ERROR: Failed to start VM after $MAX_RESTART_ATTEMPTS attempts"
            exit 1
        fi
    else
        log_message "VM '$VM_NAME' is running normally"
    fi
}

# Execute main function
main

```