v2.1 Webhook script for Internet connectivity loss on specific interface

#!/bin/bash

# Default values for options
PING_IP="8.8.8.8"      # Default ping IP address (Google DNS)
DNS_CHECK_ADDRESS="github.com"  # Default DNS check address
INTERFACE="eth0"      # Replace with your Ethernet interface name (e.g., eth0)
DISCORD_WEBHOOK_URLS=("YOUR_DISCORD_WEBHOOK_URL")  # Default Discord webhook URL(s) (comma-separated)
HA_WEBHOOK_URLS=("YOUR_HOME_ASSISTANT_WEBHOOK_URL") # Default Home Assistant webhook URL(s) (comma-separated)
DISCORD_SEND_NOTIFICATION=""  # Option to specify the type of Discord notification to send (connectivity_down, connectivity_restored, dns_failure, dns_restored, empty for all)
HA_SEND_NOTIFICATION=""  # Option to specify the type of Home Assistant notification to send (connectivity_down, connectivity_restored, dns_failure, dns_restored, empty for all)
ENABLE_RESTORE_NOTIFICATION=true   # Set this to false if you want to disable the notification when connectivity is restored
LOCK_FILE="/tmp/internet_monitor.lock" # Define the lock file path
PREVIOUS_CONNECTIVITY_STATUS="connected"  # Variable to track previous connectivity status
PREVIOUS_DNS_STATUS="resolved"  # Variable to track previous DNS resolution status

# Function to acquire the lock
acquire_lock() {
    if [[ -e "$LOCK_FILE" ]]; then
        echo "Lock file exists. Script is already running or a previous run didn't finish."
        exit 1
    fi
    touch "$LOCK_FILE"
}

# Function to release the lock
release_lock() {
    rm -f "$LOCK_FILE"
}

# Function to send a webhook notification (Discord)
send_discord_notification() {
    local message="$1"
    local payload="{\"content\":\"$message\"}"
    for url in "${DISCORD_WEBHOOK_URLS[@]}"; do
        curl -X POST -H "Content-Type: application/json" -d "$payload" "$url"
    done
}

# Function to send a webhook notification to Home Assistant
send_home_assistant_notification() {
    local message="$1"
    local payload="$2"
    for url in "${HA_WEBHOOK_URLS[@]}"; do
        curl -X POST -H "Content-Type: application/json" -d "{\"text\":\"$message\",\"payload\":\"$payload\"}" "$url"
    done
}

# Function to check internet connectivity
check_internet_connectivity() {
    local ip_address="$1"
    if ping -I "$INTERFACE" -c 1 "$ip_address" &> /dev/null; then
        return 0  # Internet connectivity is available
    else
        return 1  # Internet connectivity is not available
    fi
}

# Function to check DNS resolution
check_dns_resolution() {
    local dns_address="$1"
    if ping -I "$INTERFACE" -c 1 "$dns_address" &> /dev/null; then
        return 0  # DNS resolution is successful
    else
        return 1  # DNS resolution failed
    fi
}

# Main function to monitor internet connectivity and DNS resolution
main() {
    if ! check_internet_connectivity "$PING_IP"; then
        # Internet connectivity is not available
        if [[ "$DISCORD_SEND_NOTIFICATION" == "connectivity_down" || -z "$DISCORD_SEND_NOTIFICATION" ]]; then
            # Send Discord webhook notification for internet connectivity down
            message="Internet connectivity is down on $INTERFACE at $(date)"
            send_discord_notification "$message"
        fi

        if [[ "$HA_SEND_NOTIFICATION" == "connectivity_down" || -z "$HA_SEND_NOTIFICATION" || "$HA_NOTIFICATION_ONLY" == true ]]; then
            # Send Home Assistant webhook notification for internet connectivity down
            send_home_assistant_notification "Internet connectivity is down" "connectivity_down"
        fi

        # Update previous connectivity status to "disconnected"
        PREVIOUS_CONNECTIVITY_STATUS="disconnected"
    else
        # Internet connectivity is restored
        if [[ "$PREVIOUS_CONNECTIVITY_STATUS" == "disconnected" && ( "$DISCORD_SEND_NOTIFICATION" == "connectivity_restored" || -z "$DISCORD_SEND_NOTIFICATION" ) ]]; then
            # Send Discord webhook notification for internet connectivity restored
            message="Internet connectivity restored on $INTERFACE at $(date)"
            send_discord_notification "$message"
        fi

        if [[ "$PREVIOUS_CONNECTIVITY_STATUS" == "disconnected" && ( "$HA_SEND_NOTIFICATION" == "connectivity_restored" || -z "$HA_SEND_NOTIFICATION" || "$HA_NOTIFICATION_ONLY" == true ) ]]; then
            # Send Home Assistant webhook notification for internet connectivity restored
            send_home_assistant_notification "Internet connectivity restored" "connectivity_restored"
        fi

        # Update previous connectivity status to "connected"
        PREVIOUS_CONNECTIVITY_STATUS="connected"
    fi

    if ! check_dns_resolution "$DNS_CHECK_ADDRESS"; then
        # DNS resolution failed
        if [[ "$DISCORD_SEND_NOTIFICATION" == "dns_failure" || -z "$DISCORD_SEND_NOTIFICATION" ]]; then
            # Send Discord webhook notification for DNS resolution failed
            message="DNS resolution failed on $INTERFACE at $(date)"
            send_discord_notification "$message"
        fi

        if [[ "$HA_SEND_NOTIFICATION" == "dns_failure" || -z "$HA_SEND_NOTIFICATION" || "$HA_NOTIFICATION_ONLY" == true ]]; then
            # Send Home Assistant webhook notification for DNS resolution failed
            send_home_assistant_notification "DNS resolution failed" "dns_failure"
        fi

        # Update previous DNS resolution status to "failed"
        PREVIOUS_DNS_STATUS="failed"
    else
        # DNS resolution is successful
        if [[ "$PREVIOUS_DNS_STATUS" == "failed" && ( "$DISCORD_SEND_NOTIFICATION" == "dns_restored" || -z "$DISCORD_SEND_NOTIFICATION" ) ]]; then
            # Send Discord webhook notification for DNS resolution restored
            message="DNS resolution restored on $INTERFACE at $(date)"
            send_discord_notification "$message"
        fi

        if [[ "$PREVIOUS_DNS_STATUS" == "failed" && ( "$HA_SEND_NOTIFICATION" == "dns_restored" || -z "$HA_SEND_NOTIFICATION" || "$HA_NOTIFICATION_ONLY" == true ) ]]; then
            # Send Home Assistant webhook notification for DNS resolution restored
            send_home_assistant_notification "DNS resolution restored" "dns_restored"
        fi

        # Update previous DNS resolution status to "resolved"
        PREVIOUS_DNS_STATUS="resolved"
    fi
}

# Function to display usage information
usage() {
    echo "Usage: $0 [-p ping_ip_address] [-d dns_check_address] [-w discord_webhook_urls] [-h ha_webhook_urls] [-n notification_type] [-o]"
    echo "Options:"
    echo "  -p ping_ip_address       Specify the IP address for internet connectivity check (default: 8.8.8.8)"
    echo "  -d dns_check_address     Specify the DNS address for DNS resolution check (default: github.com)"
    echo "  -w discord_webhook_urls  Specify one or multiple Discord webhook URLs as a comma-separated list"
    echo "  -h ha_webhook_urls       Specify one or multiple Home Assistant webhook URLs as a comma-separated list"
    echo "  -n notification_type     Specify the type of notification to send (connectivity_down, dns_failure, connectivity_restored)"
    echo "  -o                       Send Home Assistant notification exclusively"
    exit 1
}

# Parse command-line options using getopts
while getopts ":p:d:w:h:n:o" opt; do
    case "$opt" in
        p) PING_IP=$OPTARG ;;
        d) DNS_CHECK_ADDRESS=$OPTARG ;;
        w) IFS=',' read -ra DISCORD_WEBHOOK_URLS <<< "$OPTARG" ;;
        h) IFS=',' read -ra HA_WEBHOOK_URLS <<< "$OPTARG" ;;
        n)
            SEND_NOTIFICATION=$OPTARG
            # Separate the SEND_NOTIFICATION option for Discord and Home Assistant
            DISCORD_SEND_NOTIFICATION=$SEND_NOTIFICATION
            HA_SEND_NOTIFICATION=$SEND_NOTIFICATION
            ;;
        o) HA_NOTIFICATION_ONLY=true ;;
        \?) echo "Invalid option: -$OPTARG" >&2 ; usage ;;
        :) echo "Option -$OPTARG requires an argument." >&2 ; usage ;;
    esac
done

# Acquire the lock before starting the main loop
acquire_lock

# Run the main loop
while true; do
    main
    sleep 1m  # Adjust the time interval as needed for internet connectivity and DNS resolution checks
done

# Release the lock when the script exits
release_lock