# Add Custom Boot Hook to /mnt/jrc-comms/hooks/boot.d

This guide explains how to add a custom boot hook to /mnt/jrc-comms/hooks/boot.d/ in applications that execute scripts in numerical order. Follow these steps to ensure proper execution order and functionality.

Assumption:

We assume you have root access to modify files in /mnt/jrc-comms/hooks/boot.d/.

# Create Custom Boot Hook

# 1. Create Your Script

Create a new shell script with a filename starting with 99- (to ensure it runs last). For example:

#!/bin/bash
/mnt/jrc-comms/hooks/boot.d/99-custom-task

echo "Running custom boot task..."

# 2. Set Permissions and Ownership

Make the script executable and ensure it’s owned by root:

sudo chown root:root /mnt/jrc-comms/hooks/boot.d/99-custom-task
sudo chmod +x /mnt/jrc-comms/hooks/boot.d/99-custom-task

# 3. Verify Execution Order

The application runs scripts in ascending order based on their numeric prefixes. Scripts added to /mnt/jrc-comms/hooks/boot.d will be injected into /opt/jrc/hooks/boot.d based on script prefix automatically. For example:

05-mount-recovery-mount runs first (found in /opt/jrc/hooks/boot.d)
10-cluster-clean runs next (found in /opt/jrc/hooks/boot.d)
99-custom-task runs last (added to /mnt/jrc-comms/hooks/boot.d)

Key rules:

Prefixes determine execution order (e.g., 00- to 99-)
Use two-digit numbering for clarity (e.g., 05-, 10-, 99-)
Scripts with the same prefix may execute in lexicographical order, but avoid ambiguity by using unique prefixes
Scripts added to /mnt/jrc-comms/hooks/boot.d will persist AMI upgrades, stack clones, etc.

By following this structure, you can extend the boot process with custom logic while maintaining predictable execution order.

# Example Walkthrough

To log system time at the end of the boot process:

#!/bin/bash
/mnt/jrc-comms/hooks/boot.d/99-custom-task

LOGFILE="/var/log/custom-boot.log"
echo "Boot completed at: $(date)" >> $LOGFILE

# Troubleshooting Tips

# 1. Test your script manually before relying on the boot process:

sudo /mnt/jrc-comms/hooks/boot.d/99-custom-task

# 2. Check logs for errors (e.g., `/var/log/syslog` or `journalctl`)

# 3. Validate script syntax using:

bash -n /mnt/jrc-comms/hooks/boot.d/99-custom-task

# Alternative to fstab Mounting Using Boot Hook Script

AutoPilot's boot hook system provides a more reliable alternative to /etc/fstab for bind mounts within dynamic environments, particularly when dealing with paths that might not be available during early boot stages.

The following is an example of how you would implement a boot hook script to create hard links. Typically this would be accomplished within /etc/fstab.

# Boot Hook Script Implementation

# 1. Create `/mnt/jrc-comms/hooks/boot.d/99-links` Script

Creates bind mounts after filesystems are available

#!/bin/bash
/mnt/jrc-comms/hooks/boot.d/99-links

echo "Creating bind mounts..."
mount --bind /var/www/domain.com/shared/var/salesexport /home/user/salesexport
mount --bind /var/www/domain.com/shared/media/importexport /home/user/importexport

# 2. Set Permissions

sudo chmod +x /mnt/jrc-comms/hooks/boot.d/99-links
sudo chown root:root /mnt/jrc-comms/hooks/boot.d/99-links

# Verification

# 1. Validate script syntax:

bash -n /mnt/jrc-comms/hooks/boot.d/99-custom-task

# 2. Check active mounts:

mount | grep bind