Migrate pi-hole A and CNAME dns records to AdGuard DNS Rewrite rules

migrate-dns-rewrites.py

import sys
import yaml
import re
from typing import List, Dict, Any

class NoAliasDumper(yaml.SafeDumper):
    """Custom YAML dumper that ignores aliases."""
    def ignore_aliases(self, data):
        return True

def parse_custom_hosts(custom_list_content: str) -> List[Dict[str, str]]:
    """Parse Pi-hole custom.list format into list of host records."""
    records = []
    
    for line in custom_list_content.strip().split('\n'):
        line = line.strip()
        if not line or line.startswith('#'):
            continue
            
        # Split line into IP and hostname
        parts = line.split()
        if len(parts) != 2:
            continue
            
        ip_address, hostname = parts
        
        # Validate IP address format
        if not re.match(r'^(?:\d{1,3}\.){3}\d{1,3}$', ip_address):
            print(f"Warning: Skipping invalid IP address: {ip_address}", file=sys.stderr)
            continue
            
        # Create rewrite record
        records.append({
            'domain': hostname,
            'answer': ip_address
        })
    
    return records

def parse_cname_records(cname_content: str) -> List[Dict[str, str]]:
    """Parse Pi-hole CNAME records into list of CNAME mappings."""
    records = []
    
    for line in cname_content.strip().split('\n'):
        line = line.strip()
        if not line or line.startswith('#'):
            continue
            
        # Parse CNAME record format: cname=alias,target
        if not line.startswith('cname='):
            continue
            
        # Remove 'cname=' prefix and split into alias and target
        mapping = line[6:].split(',')
        if len(mapping) != 2:
            continue
            
        alias, target = mapping
        
        # Create rewrite record
        records.append({
            'domain': alias,
            'answer': target
        })
    
    return records

def create_adguard_config(host_records: List[Dict[str, str]], 
                         cname_records: List[Dict[str, str]]) -> Dict[str, Any]:
    """Create AdGuard Home configuration structure."""
    # Combine all records
    all_records = host_records + cname_records
    
    # Create config structure
    config = {
        'dns': {
            'rewrites': all_records
        }
    }
    
    return config

def main():
    if len(sys.argv) != 3:
        print("Usage: python script.py <custom.list> <05-pihole-custom-cname.conf>")
        sys.exit(1)

    custom_list_file = sys.argv[1]
    cname_file = sys.argv[2]

    # Read input files
    try:
        with open(custom_list_file, 'r') as f:
            custom_list_content = f.read()
    except FileNotFoundError:
        print(f"Error: Custom hosts file {custom_list_file} not found", file=sys.stderr)
        sys.exit(1)

    try:
        with open(cname_file, 'r') as f:
            cname_content = f.read()
    except FileNotFoundError:
        print(f"Error: CNAME file {cname_file} not found", file=sys.stderr)
        sys.exit(1)

    # Parse records
    host_records = parse_custom_hosts(custom_list_content)
    cname_records = parse_cname_records(cname_content)

    # Create config
    config = create_adguard_config(host_records, cname_records)

    # Output YAML
    print(yaml.dump(config, Dumper=NoAliasDumper, default_flow_style=False, 
                   sort_keys=False, width=float("inf")))

if __name__ == "__main__":
    main()