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Converting to a class, commenting methods, reading settings from a

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config file, and starting to work on the host variables
pull/600/head
Peter Sankauskas 12 years ago
parent 43eb3214a6
commit a940c9b8fb
2 changed files with 274 additions and 115 deletions
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37
examples/scripts/ec2.ini
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# Ansible EC2 external inventory script settings
#
[ec2]
# When generating inventory, Ansible needs to know how to address a server.
# Each EC2 instance has a lot of variables associated with it. Here is the list:
# http://docs.pythonboto.org/en/latest/ref/ec2.html#module-boto.ec2.instance
# Below are 2 variables that are used as the address of a server:
# - destination_variable
# - vpc_destination_variable
# This is the normal destination variable to use. If you are running Ansible
# from outside EC2, then 'public_dns_name' makes the most sense. If you are
# running Ansible from within EC2, then perhaps you want to use the internal
# address, and should set this to 'private_dns_name'.
destination_variable = public_dns_name
# For server inside a VPC, using DNS names may not make sense. When an instance
# has 'subnet_id' set, this variable is used. If the subnet is public, setting
# this to 'ip_address' will return the public IP address. For instances in a
# private subnet, this should be set to 'private_ip_address', and Ansible must
# be run from with EC2.
vpc_destination_variable = ip_address
# API calls to EC2 are slow. For this reason, we cache the results of an API
# call. Set this to the path you want cache files to be written to. Two files
# will be written to this directory:
# - ansible-ec2.cache
# - ansible-ec2.index
cache_path = /tmp
# The number of seconds a cache file is considered valid. After this many
# seconds, a new API call will be made, and the cache file will be updated.
cache_max_age = 300

352
examples/scripts/ec2_external_inventory.py
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#!/usr/bin/python -tt
"""
'''
EC2 external inventory script
=================================
@ -9,13 +9,94 @@ variables needed for Boto have been set:
export AWS_ACCESS_KEY_ID=''
export AWS_SECRET_ACCESS_KEY=''
For more details, see: http://docs.pythonboto.org/en/latest/boto_config_tut.html
"""
mdehaan
1:14 I'd break the get_instances_by_region function up so it calls a few smaller functions
1:18 each function having a comment is a good thing
1:19 parser script needs to support taking a hostname to get the variables, right?
1:22 pas256: read the source to the cobbler inventory script
1:22 it has two modes... list all my groups
1:22 and another is for this given host, what variables do I use
mdehaan
1:23 if you are not actually generating the file, and are using it as a param to -i, it will need to do both
mdehaan
1:23 API is not as friendly as YAML or JSON, but it is ok
1:23 I will not do YAML config files again if I can help it
pas256
1:26 Ooo I missed that functionality so `script --list hostname` returns just a JSON object with whatever variables that host has
1:26 very cool
1:26 I can add that
mdehaan
1:26 no
1:26 script --list is one way it is executed
1:26 script --host <hostname>, is the other, I believe
pas256
1:26 o ok
mdehaan
1:27 looks like the cobbler one needs fixing up
1:27 pilt [~pilt@h-60-43.a163.priv.bahnhof.se] entered the room.
mdehaan
1:27 sorry about that, clear no one is using it
pas256
1:27 the cobbler script doesn't care what the first arg is, only the count
1:27 lol yeah
mdehaan
1:27 I really kinda like the idea of just generating the inventory file
1:27 maybe it should just do that
1:27 faster, no need to cache
1:27 plus it's a nice record of exactly what it will use
pas256
1:27 but with EC2, it is always changing
1:28 at least for us it is
mdehaan
1:28 https://github.com/ansible/ansible/issues/560
mdehaan
1:29 pas256: yeah, true
mdehaan
1:29 either way
1:29 pilt left the room (quit: Client Quit).
mdehaan
1:29 you could still run it if you wanted to look
pas256
1:30 yep
mdehaan
1:31 so assuming there is a metadata way to get variables out of EC2 you could store them with the host
1:31 and let ansible see all of them or some of them
pas256
1:32 yeah the instance object has a lot of data in it, I am only grouping by what makes sense to group by
mdehaan
1:33 can you define your own namespaces for variables? Maybe there could be an ansible one...
1:33 though there shouldn't be a lot of host specific variables really
1:33 group specific variables are nice to support though
1:33 I can see use in that
pas256
1:33 ec2_ everything?
mdehaan
1:33 webservers get fooserver=xyz.example.com
1:33 you need some way of doing stuff like that
1:34 I don't know EC2's API at all
1:34 or EC2, really
pas256
1:34 AWS in general is pretty sweet there is a lot to it
mdehaan
1:35 yeah, seems like you could spend a long time learning all their various services
1:35 it's kind of a specialization in itself
pas256
1:35 agreed
'''
import os
import argparse
import re
from time import time
from boto import ec2
import ConfigParser
try:
import json
@ -23,126 +104,167 @@ except ImportError:
import simplejson as json
### Settings
# I can see other uses where this variable is something else, say if someone
# is running Ansible within EC2, these might be internal IP addresses
destinationVariable = "public_dns_name"
vpcDestinationVariable = "ip_address"
cachePath = "/tmp/ansible-ec2.cache"
cacheMaxAge = 300 # seconds
# 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('--refresh-cache', action='store_true', default=False,
help='refreshes the cache by making API requests to EC2 (default: False, use cache)')
args = parser.parse_args()
# Instance IDs, tags, security groups, regions, availability zones
inventory = {}
def doApiCall(regionInfo):
# Loop over all regions
region = regionInfo.name
conn = ec2.connect_to_region(region)
inventory[region] = []
reservations = conn.get_all_instances()
for reservation in reservations:
for instance in reservation.instances:
if instance.state == 'terminated':
continue
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()
# Force cache refresh?
if self.args.refresh_cache:
json_inventory = self.do_api_calls_update_cache()
# Select the best destination address
if instance.subnet_id:
dest = getattr(instance, vpcDestinationVariable)
else:
dest = getattr(instance, destinationVariable)
if dest == None:
# Skip instances we cannot address (e.g. VPC private subnet)
continue
# Group by instance ID (always a group of 1)
inventory[instance.id] = [dest]
#
if self.args.host:
print self.args.host
# Group by region
inventory[region].append(dest);
# Group by availability zone
if instance.placement in inventory:
inventory[instance.placement].append(dest);
elif 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:
# Use cache
json_inventory = self.get_inventory_from_cache()
else:
inventory[instance.placement] = [dest]
json_inventory = self.do_api_calls_update_cache()
else:
json_inventory = self.do_api_calls_update_cache()
# Group by security group
for group in instance.groups:
key = toSafe("security-group_" + group.name)
if key in inventory:
inventory[key].append(dest);
print json_inventory
print self.json_format_dict(self.index, True)
def read_settings(self):
''' Reads the settings from the ec2.ini file '''
config = ConfigParser.SafeConfigParser()
config.read('ec2.ini')
self.destination_variable = config.get('ec2', 'destination_variable')
self.vpc_destination_variable = config.get('ec2', 'vpc_destination_variable')
cache_path = config.get('ec2', 'cache_path')
self.cache_max_age = config.getint('ec2', 'cache_max_age')
self.cache_path_cache = cache_path + "/ansible-ec2.cache"
self.cache_path_index = cache_path + "/ansible-ec2.index"
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 regionInfo in ec2.regions():
region = regionInfo.name
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)
self.inventory[region] = []
reservations = conn.get_all_instances()
for reservation in reservations:
for instance in reservation.instances:
if instance.state == 'terminated':
continue
# Select the best destination address
if instance.subnet_id:
dest = getattr(instance, self.vpc_destination_variable)
else:
inventory[key] = [dest]
# Group by tag keys
for k, v in instance.tags.iteritems():
key = toSafe("tag_" + k + "=" + v)
if key in inventory:
inventory[key].append(dest);
dest = getattr(instance, self.destination_variable)
if dest == None:
# Skip instances we cannot address (e.g. VPC private subnet)
continue
# Add to index
self.index[dest] = [region, instance.id]
# Group by instance ID (always a group of 1)
self.inventory[instance.id] = [dest]
# Group by region
self.inventory[region].append(dest);
# Group by availability zone
if instance.placement in self.inventory:
self.inventory[instance.placement].append(dest);
else:
inventory[key] = [dest]
return formatInventory(True)
def getInventoryFromCache():
cache = open(cachePath, 'r')
jsonInventory = cache.read()
return jsonInventory
def getInventoryFromApiUpdateCache():
for region in ec2.regions():
doApiCall(region)
self.inventory[instance.placement] = [dest]
# Group by security group
for group in instance.groups:
key = self.to_safe("security-group_" + group.name)
if key in self.inventory:
self.inventory[key].append(dest);
else:
self.inventory[key] = [dest]
# Group by tag keys
for k, v in instance.tags.iteritems():
key = self.to_safe("tag_" + k + "=" + v)
if key in self.inventory:
self.inventory[key].append(dest);
else:
self.inventory[key] = [dest]
return self.json_format_dict(self.inventory, True)
jsonInventory = formatInventory(True)
cache = open(cachePath, 'w')
cache.write(jsonInventory)
cache.close()
return jsonInventory
def get_inventory_from_cache(self):
cache = open(self.cache_path_cache, 'r')
json_inventory = cache.read()
return json_inventory
def toSafe(word):
return re.sub("[^A-Za-z0-9\-]", "_", word)
def formatInventory(pretty=False):
if pretty:
return json.dumps(inventory, sort_keys=True, indent=2)
else:
return json.dumps(inventory)
# Do work here
if args.refresh_cache:
jsonInventory = getInventoryFromApiUpdateCache()
def get_index_from_cache(self):
cache = open(self.cache_path_index, 'r')
json_index = cache.read()
return json_index
elif os.path.isfile(cachePath):
modTime = os.path.getmtime(cachePath)
currentTime = time()
if (modTime + cacheMaxAge) > currentTime:
# Use cache
jsonInventory = getInventoryFromCache()
else:
jsonInventory = getInventoryFromApiUpdateCache()
else:
jsonInventory = getInventoryFromApiUpdateCache()
def write_to_cache(self, data, file):
json_data = self.json_format_dict(data, True)
cache = open(file, '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)
print jsonInventory
# Run the script
Ec2Inventory()

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