Nagios active probes every service
          │
          ▼
   Check result: OK / WARNING / CRITICAL / UNKNOWN
          │
          ├── OK → green in UI, no action
          ├── WARNING → yellow, soft alert
          └── CRITICAL → red, hard alert + notification

define service {
    host_name               coderz-server
    service_description     HTTP - My New Service
    check_command           check_http_port!PORT!/PATH
    check_interval          1
    retry_interval          1
    max_check_attempts      3
    check_period            24x7
    notification_interval   10
    notification_period     24x7
    contact_groups          admins
}

docker compose -f /opt/coderz/docker-compose.yml restart nagios

# HTTP check on a specific port and path
define command {
    command_name    check_http_port
    command_line    $USER1$/check_http -H 109.199.120.120 -p $ARG1$ -u $ARG2$ -t 10
}

# TCP port check
define command {
    command_name    check_tcp_port
    command_line    $USER1$/check_tcp -H 109.199.120.120 -p $ARG1$ -t 10
}

nagios:
  image: jasonrivers/nagios:latest
  container_name: coderz-nagios
  ports:
    - "8089:80"
  environment:
    - NAGIOSADMIN_USER=nagiosadmin
    - NAGIOSADMIN_PASS=coderz123
  volumes:
    - ./configs/nagios:/etc/nagios4/conf.d/coderz:ro
    - ./configs/nagios/cgi.cfg:/opt/nagios/etc/cgi.cfg:ro
    - /proc:/hostfs/proc:ro
    - /sys:/hostfs/sys:ro
    - /:/hostfs/root:ro
  networks:
    - coderz-net