Write EC2 hosts to ssh_config

write_ec2_hosts.py

"""
First generate the hosts.yaml file using the ec2.py inventory script.
 
./inventory/ec2.py --refresh-cache > hosts.yaml
"""

import os
import yaml

user = "ec2-user"
config = "/home/"+user+"/.ssh/config"

hosts = open("hosts.yaml", 'r')
hosts_yaml = yaml.load(hosts)

# Add any static hosts to the config first.
ssh_config = open(config, 'w')
write_line = "Host %s\nUser %s\nHostname %s\nIdentityFile ~/.ssh/%s\n\n" % (
                                "github.com",
                                "git",
                                "github.com",
                                "id_rsa")
ssh_config.write(write_line)
ssh_config.close()

# Open the dynamic hosts file and look at each host
for host in hosts_yaml['_meta']['hostvars']:
    # Check to see if our host has a public or private address
    if hosts_yaml['_meta']['hostvars'][host]['ec2_dns_name'] != "":
        write_line = "\nHost %s\nUser %s\nHostname %s\nIdentityFile ~/.ssh/%s\n\n" % (
                                hosts_yaml['_meta']['hostvars'][host]['ec2_dns_name'],
                                user,
                                hosts_yaml['_meta']['hostvars'][host]['ec2_dns_name'],
                                hosts_yaml['_meta']['hostvars'][host]['ec2_key_name'])
    elif hosts_yaml['_meta']['hostvars'][host]['ec2_private_dns_name'] != "":
        write_line = "\nHost %s\nUser %s\nHostname %s\nIdentityFile ~/.ssh/%s\n\n" % (
                                hosts_yaml['_meta']['hostvars'][host]['ec2_private_dns_name'],
                                user,
                                hosts_yaml['_meta']['hostvars'][host]['ec2_private_dns_name'],
                                hosts_yaml['_meta']['hostvars'][host]['ec2_key_name'])
    else:
        # If we couldn't determine the ip address we write the instance id instead.
        write_line = "\nHost %s\n\n" % hosts_yaml['_meta']['hostvars'][host]['ec2_id']

    # Write the config line
    ssh_config = open(config, 'a')
    ssh_config.write(write_line)
    ssh_config.close()