ansible/examples/scripts/ec2_external_inventory.py

#!/usr/bin/python -tt

'''
EC2 external inventory script
=================================

Generates inventory that Ansible can understand by making API request to
AWS EC2 using the Boto library. 

NOTE: This script assumes Ansible is being executed where the environment
variables needed for Boto have already been set:
    export AWS_ACCESS_KEY_ID='AK123'
    export AWS_SECRET_ACCESS_KEY='abc123'
    
For more details, see: http://docs.pythonboto.org/en/latest/boto_config_tut.html

When run against a specific host, this script returns the following variables:
 - ec2_ami_launch_index
 - ec2_architecture
 - ec2_association
 - ec2_attachTime
 - ec2_attachment
 - ec2_attachmentId
 - ec2_client_token
 - ec2_deleteOnTermination
 - ec2_description
 - ec2_deviceIndex
 - ec2_dns_name
 - ec2_eventsSet
 - ec2_group_name
 - ec2_hypervisor
 - ec2_id
 - ec2_image_id
 - ec2_instanceState
 - ec2_instance_type
 - ec2_ipOwnerId
 - ec2_ip_address
 - ec2_item
 - ec2_kernel
 - ec2_key_name
 - ec2_launch_time
 - ec2_monitored
 - ec2_monitoring
 - ec2_networkInterfaceId
 - ec2_ownerId
 - ec2_persistent
 - ec2_placement
 - ec2_platform
 - ec2_previous_state
 - ec2_private_dns_name
 - ec2_private_ip_address
 - ec2_publicIp
 - ec2_public_dns_name
 - ec2_ramdisk
 - ec2_reason
 - ec2_region
 - ec2_requester_id
 - ec2_root_device_name
 - ec2_root_device_type
 - ec2_security_group_ids
 - ec2_security_group_names
 - ec2_shutdown_state
 - ec2_sourceDestCheck
 - ec2_spot_instance_request_id
 - ec2_state
 - ec2_state_code
 - ec2_state_reason
 - ec2_status
 - ec2_subnet_id
 - ec2_tenancy
 - ec2_virtualization_type
 - ec2_vpc_id

These variables are pulled out of a boto.ec2.instance object. There is a lack of
consistency with variable spellings (camelCase and underscores) since this
just loops through all variables the object exposes. It is preferred to use the
ones with underscores when multiple exist.

In addition, if an instance has AWS Tags associated with it, each tag is a new
variable named:
 - ec2_tag_[Key] = [Value]

Security groups are comma-separated in 'ec2_security_group_ids' and 
'ec2_security_group_names'.
'''

# (c) 2012, Peter Sankauskas
#
# This file is part of Ansible,
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

######################################################################

import os
import argparse
import re
from time import time
from boto import ec2
import ConfigParser

try:
    import json
except ImportError:
    import simplejson as json


class Ec2Inventory(object):
    def __init__(self):
        ''' Main execution path '''
        
        # Inventory grouped by instance IDs, tags, security groups, regions,
        # and availability zones
        self.inventory = {}
        
        # Index of hostname (address) to instance ID
        self.index = {}
        
        # Read settings and parse CLI arguments
        self.read_settings()
        self.parse_cli_args()
        
        # Cache
        if self.args.refresh_cache:
            self.do_api_calls_update_cache()  
        elif not self.is_cache_valid():
            self.do_api_calls_update_cache()
        
        # Data to print
        if self.args.host:
            data_to_print = self.get_host_info()
        
        elif self.args.list:
            # Display list of instances for inventory
            if len(self.inventory) == 0:
                data_to_print = self.get_inventory_from_cache()
            else:
                data_to_print = self.json_format_dict(self.inventory, True)
              
        print data_to_print
        
        
    def is_cache_valid(self):
        ''' Determines if the cache files have expired, or if it is still valid '''

        if os.path.isfile(self.cache_path_cache):
            mod_time = os.path.getmtime(self.cache_path_cache)
            current_time = time()
            if (mod_time + self.cache_max_age) > current_time:
                if os.path.isfile(self.cache_path_index):
                    return True
                
        return False
        
        
    def read_settings(self):
        ''' Reads the settings from the ec2.ini file '''
        
        config = ConfigParser.SafeConfigParser()
        config.read(os.path.dirname(os.path.realpath(__file__)) + '/ec2.ini')
        
        # Regions
        self.regions = []
        configRegions = config.get('ec2', 'regions')
        if (configRegions == 'all'):
            for regionInfo in ec2.regions():
                self.regions.append(regionInfo.name)
        else:
            self.regions = configRegions.split(",")
        
        # Destination addresses
        self.destination_variable = config.get('ec2', 'destination_variable')
        self.vpc_destination_variable = config.get('ec2', 'vpc_destination_variable')

        # Cache related
        cache_path = config.get('ec2', 'cache_path')
        self.cache_path_cache = cache_path + "/ansible-ec2.cache"
        self.cache_path_index = cache_path + "/ansible-ec2.index"
        self.cache_max_age = config.getint('ec2', 'cache_max_age')
        
        
    def parse_cli_args(self):
        ''' Command line argument processing '''
        
        parser = argparse.ArgumentParser(description='Produce an Ansible Inventory file based on EC2')
        parser.add_argument('--list', action='store_true', default=True, 
                           help='List instances (default: True)')
        parser.add_argument('--host', action='store', 
                           help='Get all the variables about a specific instance')
        parser.add_argument('--refresh-cache', action='store_true', default=False, 
                           help='Force refresh of cache by making API requests to EC2 (default: False - use cache files)')
        self.args = parser.parse_args()
        
        
    def do_api_calls_update_cache(self):
        ''' Do API calls to each region, and save data in cache files '''
        
        for region in self.regions:
            self.get_instances_by_region(region)
        
        self.write_to_cache(self.inventory, self.cache_path_cache)
        self.write_to_cache(self.index, self.cache_path_index)


    def get_instances_by_region(self, region):
        ''' Makes an AWS EC2 API call to the list of instances in a particular
        region '''
        
        conn = ec2.connect_to_region(region)
        reservations = conn.get_all_instances()
        for reservation in reservations:
            for instance in reservation.instances:
                self.add_instance(instance, region)


    def get_instance(self, region, instance_id):
        ''' Gets details about a specific instance '''
        conn = ec2.connect_to_region(region)
        reservations = conn.get_all_instances([instance_id])
        for reservation in reservations:
            for instance in reservation.instances:
                return instance
            
        
    def add_instance(self, instance, region):
        ''' Adds an instance to the inventory and index, as long as it is
        addressable '''
        
        # Only want running instances
        if instance.state == 'terminated':
            return
        
        # Select the best destination address
        if instance.subnet_id:
            dest = getattr(instance, self.vpc_destination_variable)
        else:
            dest =  getattr(instance, self.destination_variable)

        if dest == None:
            # Skip instances we cannot address (e.g. private VPC subnet)
            return

        # Add to index
        self.index[dest] = [region, instance.id]

        # Inventory: Group by instance ID (always a group of 1)
        self.inventory[instance.id] = [dest]
        
        # Inventory: Group by region
        self.push(self.inventory, region, dest)
                        
        # Inventory: Group by availability zone
        self.push(self.inventory, instance.placement, dest)
        
        # Inventory: Group by security group
        for group in instance.groups:
            key = self.to_safe("security_group_" + group.name)
            self.push(self.inventory, key, dest)
                
        # Inventory: Group by tag keys
        for k, v in instance.tags.iteritems():
            key = self.to_safe("tag_" + k + "=" + v)
            self.push(self.inventory, key, dest)        
    
    
    def get_host_info(self):
        ''' Get variables about a specific host '''
        
        if len(self.index) == 0:
            # Need to load index from cache
            self.load_index_from_cache()
        
        (region, instance_id) = self.index[self.args.host]
        instance = self.get_instance(region, instance_id)
        instance_vars = {}
        for key in vars(instance):
            value = getattr(instance, key)
            key = self.to_safe('ec2_' + key)
            
            # Handle complex types
            if type(value) in [int, bool]:
                instance_vars[key] = value
            elif type(value) in [str, unicode]:
                instance_vars[key] = value.strip()
            elif type(value) == type(None):
                instance_vars[key] = ''
            elif key == 'ec2_region':
                instance_vars[key] = value.name
            elif key == 'ec2_tags':
                for k, v in value.iteritems():
                    key = self.to_safe('ec2_tag_' + k)
                    instance_vars[key] = v
            elif key == 'ec2_groups':
                group_ids = []
                group_names = []
                for group in value:
                    group_ids.append(group.id)
                    group_names.append(group.name)
                instance_vars["ec2_security_group_ids"] = ','.join(group_ids)
                instance_vars["ec2_security_group_names"] = ','.join(group_names)
            else:
                pass
                # TODO Product codes if someone finds them useful
                #print key
                #print type(value)
                #print value
                           
        return self.json_format_dict(instance_vars, True)        
    
    
    def push(self, my_dict, key, element):
        ''' Pushed an element onto an array that may not have been defined in
        the dict '''
        
        if key in my_dict:
            my_dict[key].append(element);
        else:
            my_dict[key] = [element]        
    
    
    def get_inventory_from_cache(self):
        ''' Reads the inventory from the cache file and returns it as a JSON
        object '''

        cache = open(self.cache_path_cache, 'r')
        json_inventory = cache.read()
        return json_inventory


    def load_index_from_cache(self):
        ''' Reads the index from the cache file sets self.index '''

        cache = open(self.cache_path_index, 'r')
        json_index = cache.read()
        self.index = json.loads(json_index)
    
    
    def write_to_cache(self, data, filename):
        ''' Writes data in JSON format to a file '''
        
        json_data = self.json_format_dict(data, True)
        cache = open(filename, 'w')
        cache.write(json_data)
        cache.close()
        
        
    def to_safe(self, word):
        ''' Converts 'bad' characters in a string to underscores so they can be
        used as Ansible groups '''
        
        return re.sub("[^A-Za-z0-9\-]", "_", word)
        
        
    def json_format_dict(self, data, pretty=False):
        ''' Converts a dict to a JSON object and dumps it as a formatted
        string '''
        
        if pretty:
            return json.dumps(data, sort_keys=True, indent=2)
        else:
            return json.dumps(data)
        
    
# Run the script
Ec2Inventory()