Sync /etc/hosts with Azure vms adresses

0_update_hosts_from_azure_vms.sh

#!/bin/bash

set -euo pipefail

# Configuration
HOSTS_FILE="/etc/hosts"
BACKUP_DIR="$HOME/.azure_hosts_backups"
AZURE_MARKER_START="# === AZURE VMs START ==="
AZURE_MARKER_END="# === AZURE VMs END ==="

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

log_info() {
    echo -e "${GREEN}[INFO]${NC} $1"
}

log_warn() {
    echo -e "${YELLOW}[WARN]${NC} $1"
}

log_error() {
    echo -e "${RED}[ERROR]${NC} $1"
}

# Check if Azure CLI is installed
check_azure_cli() {
    if ! command -v az &> /dev/null; then
        log_error "Azure CLI is not installed. Please install it first."
        exit 1
    fi
}

# Check if user is logged in to Azure
check_azure_login() {
    if ! az account show &> /dev/null; then
        log_error "Not logged in to Azure. Please run 'az login' first."
        exit 1
    fi
}

# Create backup directory
create_backup_dir() {
    mkdir -p "$BACKUP_DIR"
}

# Backup current hosts file
backup_hosts_file() {
    local timestamp=$(date +"%Y%m%d_%H%M%S")
    local backup_file="$BACKUP_DIR/hosts_backup_$timestamp"
    
    if cp "$HOSTS_FILE" "$backup_file"; then
        log_info "Hosts file backed up to: $backup_file"
    else
        log_error "Failed to backup hosts file"
        exit 1
    fi
}

# Get VM information from Azure
get_azure_vms() {    
    # Get all VMs with their public and private IPs
    az vm list-ip-addresses --output json | jq -r '
        .[] | 
        select(.virtualMachine.network.publicIpAddresses != null and (.virtualMachine.network.publicIpAddresses | length) > 0) |
        .virtualMachine.name as $name |
        .virtualMachine.network.publicIpAddresses[0].ipAddress as $public_ip |
        (.virtualMachine.network.privateIpAddresses[0] // "") as $private_ip |
        "\($public_ip)\t\($name)\t# Azure VM (Private: \($private_ip))"
    ' 2>/dev/null || {
        log_error "Failed to fetch VM information from Azure"
        exit 1
    }
}

# Remove existing Azure VM entries from hosts file
remove_existing_azure_entries() {
    local temp_file=$(mktemp)
    
    # Remove content between markers (including markers)
    awk "
        BEGIN { skip = 0 }
        /^$AZURE_MARKER_START/ { skip = 1; next }
        /^$AZURE_MARKER_END/ { skip = 0; next }
        !skip { print }
    " "$HOSTS_FILE" > "$temp_file"
    
    if mv "$temp_file" "$HOSTS_FILE"; then
        log_info "Removed existing Azure VM entries from hosts file"
    else
        log_error "Failed to update hosts file"
        exit 1
    fi
}

# Add Azure VM entries to hosts file
add_azure_entries() {
    local vm_entries="$1"
    
    if [ -z "$vm_entries" ]; then
        log_warn "No VMs with public IPs found in Azure"
        return
    fi
    
    # Add markers and VM entries to hosts file
    {
        echo ""
        echo "$AZURE_MARKER_START"
        echo "$vm_entries"
        echo "$AZURE_MARKER_END"
    } >> "$HOSTS_FILE"
    
    log_info "Added Azure VM entries to hosts file"
}

# Display summary
show_summary() {
    local vm_count=$(echo "$1" | grep -c "^[0-9]" || echo "0")
    log_info "Summary: Added $vm_count VM entries to $HOSTS_FILE"
    
    if [ "$vm_count" -gt 0 ]; then
        echo ""
        echo "Added entries:"
        echo "$1" | while IFS=$'\t' read -r ip name comment; do
            echo "  $ip -> $name"
        done
    fi
}

# Main function
main() {
    log_info "Starting Azure VM hosts file update..."
    
    # Preliminary checks
    check_azure_cli
    check_azure_login
    
    # Check if we have write permissions to hosts file
    if [ ! -w "$HOSTS_FILE" ]; then
        log_error "No write permission to $HOSTS_FILE. Please run with sudo."
        exit 1
    fi
    
    # Setup
    create_backup_dir
    backup_hosts_file
    
    # Get VM information
    log_info "Fetching VM information from Azure..."
    vm_entries=$(get_azure_vms)
    
    # Update hosts file
    remove_existing_azure_entries
    add_azure_entries "$vm_entries"
    
    # Show results
    show_summary "$vm_entries"
    
    log_info "Azure VM hosts file update completed successfully!"
}

# Help function
show_help() {
    cat << EOF
Usage: $0 [OPTIONS]

Update /etc/hosts file with Azure VM IP addresses and names.

OPTIONS:
    -h, --help      Show this help message
    -d, --dry-run   Show what would be added without modifying hosts file

REQUIREMENTS:
    - Azure CLI installed and configured
    - Logged in to Azure (az login)
    - Write permission to /etc/hosts (run with sudo if needed)
    - jq installed for JSON parsing

EXAMPLES:
    # Update hosts file with Azure VMs
    sudo $0
    
    # See what would be added (dry run)
    $0 --dry-run

EOF
}

# Handle command line arguments
case "${1:-}" in
    -h|--help)
        show_help
        exit 0
        ;;
    -d|--dry-run)
        log_info "DRY RUN: Showing what would be added to hosts file"
        check_azure_cli
        check_azure_login
        vm_entries=$(get_azure_vms)
        if [ -n "$vm_entries" ]; then
            echo ""
            echo "Would add the following entries:"
            echo "$vm_entries"
        else
            log_warn "No VMs with public IPs found"
        fi
        exit 0
        ;;
    "")
        main
        ;;
    *)
        log_error "Unknown option: $1"
        show_help
        exit 1
        ;;
esac

1_restore_hosts_backup.sh

#!/bin/bash

set -euo pipefail

BACKUP_DIR="$HOME/.azure_hosts_backups"
HOSTS_FILE="/etc/hosts"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
NC='\033[0m'

log_info() {
    echo -e "${GREEN}[INFO]${NC} $1"
}

log_error() {
    echo -e "${RED}[ERROR]${NC} $1"
}

# List available backups
list_backups() {
    if [ ! -d "$BACKUP_DIR" ]; then
        log_error "No backup directory found at $BACKUP_DIR"
        exit 1
    fi
    
    local backups=($(ls -1t "$BACKUP_DIR"/hosts_backup_* 2>/dev/null || true))
    
    if [ ${#backups[@]} -eq 0 ]; then
        log_error "No backups found in $BACKUP_DIR"
        exit 1
    fi
    
    echo "Available backups (newest first):"
    for i in "${!backups[@]}"; do
        local backup="${backups[$i]}"
        local basename=$(basename "$backup")
        local timestamp=$(echo "$basename" | sed 's/hosts_backup_//')
        local readable_date=$(date -j -f "%Y%m%d_%H%M%S" "$timestamp" "+%Y-%m-%d %H:%M:%S" 2>/dev/null || echo "$timestamp")
        echo "  $((i+1)). $basename ($readable_date)"
    done
    
    echo ""
    read -p "Select backup number to restore (1-${#backups[@]}): " selection
    
    if [[ "$selection" =~ ^[0-9]+$ ]] && [ "$selection" -ge 1 ] && [ "$selection" -le ${#backups[@]} ]; then
        selected_backup="${backups[$((selection-1))]}"
        restore_backup "$selected_backup"
    else
        log_error "Invalid selection"
        exit 1
    fi
}

# Restore selected backup
restore_backup() {
    local backup_file="$1"
    
    if [ ! -f "$backup_file" ]; then
        log_error "Backup file not found: $backup_file"
        exit 1
    fi
    
    if [ ! -w "$HOSTS_FILE" ]; then
        log_error "No write permission to $HOSTS_FILE. Please run with sudo."
        exit 1
    fi
    
    if cp "$backup_file" "$HOSTS_FILE"; then
        log_info "Successfully restored hosts file from: $(basename "$backup_file")"
    else
        log_error "Failed to restore backup"
        exit 1
    fi
}

# Main
case "${1:-}" in
    -h|--help)
        echo "Usage: $0"
        echo "Restore /etc/hosts file from Azure VM update backups"
        exit 0
        ;;
    *)
        list_backups
        ;;
esac