Convert hosts found in a standard ssh config into Ansible YAML inventory

ssh_config_to_ansible_inventory.py

#!/usr/bin/env python3
"""
Convert SSH config file to Ansible YAML inventory
No external dependencies required - uses only standard library
"""

import os
import sys
import yaml
import re
from collections import defaultdict

def parse_ssh_config(config_path):
    """Parse SSH config file and extract host information"""
    if not os.path.exists(config_path):
        print(f"Error: SSH config file not found at {config_path}", file=sys.stderr)
        sys.exit(1)

    hosts = {}
    current_host = None

    with open(config_path, 'r') as f:
        for line in f:
            line = line.strip()
            if not line or line.startswith('#'):
                continue

            # Match Host directive which can contain multiple host patterns
            if line.lower().startswith('host '):
                host_patterns = line[5:].split()
                # We'll process each host pattern separately
                for pattern in host_patterns:
                    # Skip wildcard patterns for Ansible inventory
                    if '*' in pattern:
                        continue
                    current_host = pattern
                    hosts[current_host] = {'ansible_host': None, 'ansible_user': None}
            elif current_host and ' ' in line:
                key, value = line.split(None, 1)
                key = key.lower()

                if key == 'hostname':
                    hosts[current_host]['ansible_host'] = value
                elif key == 'user':
                    hosts[current_host]['ansible_user'] = value

    # Remove hosts that don't have hostname specified
    return {k: v for k, v in hosts.items() if v['ansible_host']}

def generate_ansible_inventory(hosts):
    """Generate Ansible inventory structure from parsed hosts"""
    inventory = {
        'all': {
            'hosts': {},
            'children': {
                'ungrouped': {
                    'hosts': {}
                }
            }
        }
    }

    # Add all hosts to the inventory
    for hostname, host_vars in hosts.items():
        inventory['all']['hosts'][hostname] = host_vars

    return inventory

def main():
    # Default SSH config path
    ssh_config_path = os.path.expanduser('~/.ssh/config')

    # Allow custom path as command line argument
    if len(sys.argv) > 1:
        ssh_config_path = sys.argv[1]

    # Parse SSH config
    hosts = parse_ssh_config(ssh_config_path)

    if not hosts:
        print("No valid hosts found in SSH config", file=sys.stderr)
        sys.exit(1)

    # Generate Ansible inventory
    inventory = generate_ansible_inventory(hosts)

    # Output as YAML
    # We need to handle the YAML output manually since PyYAML doesn't format it exactly as Ansible expects
    print("---")
    yaml.dump(inventory, sys.stdout, default_flow_style=False)

if __name__ == "__main__":
    main()