Detect NGINX configuration changes, test them, and reload NGINX automatically

auto-test-and-reload-nginx-configuration.md

This bash script monitors directories and files for changes, runs nginx -t to test the configuration, and reloads NGINX by executing nginx -s reload. All actions are being logged in /var/log/monitor.log and /var/log/monitor-errors.log.

Prerequisites

inotify-tools -> https://github.com/inotify-tools/inotify-tools

The Script

#!/bin/bash

set -o pipefail

CONFIG_DIRS=(
    "/etc/nginx/conf.d"
)

DELAY_IN_SECONDS=5

reload_nginx() {
    echo "$(date) - Changes detected, waiting for more changes..." >> /var/log/monitor.log
    sleep $DELAY_IN_SECONDS
    echo "$(date) - Delay passed, checking NGINX configuration..." >> /var/log/monitor.log
    if nginx -t 2>> /var/log/monitor-errors.log; then
        nginx -s reload
        echo "$(date) - NGINX successfully reloaded." >> /var/log/monitor.log
    else
        echo "$(date) - NGINX configuration test failed, reload skipped." >> /var/log/monitor-errors.log
    fi
}

# PID of the last reload task.
last_pid=0

inotifywait -m -r -e modify,create,delete "${CONFIG_DIRS[@]}" --format '%w%f' |
    while IFS= read -r file; do
        # Kill the last reload task if it's still running
        if [ $last_pid -ne 0 ]; then
            kill $last_pid 2>/dev/null
        fi
        # Start a new reload task in the background
        reload_nginx &
        last_pid=$!
    done