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#! /usr/bin/env python
'''
etcd dynamic inventory script
=================================
Generarates inventory for ansible from etcd using python-etcd library.
The script assumes etcd.ini to be present alongside it. To choose a different
path, set the ETCD_INI_PATH environment variable:
export ETCD_INI_PATH=/path/to/etcd.ini
All etcd variables are prefixed with /ansible by default, but this can be changed
in the etcd.ini file.
Some example keys to get an idea of how to store your data in etcd (assume prefix is '/ansible'):
## Group Variables
{prefix}/groupvars/{group}/{key}
Example:
/ansible/groupvars/group1/foo
## Host Variables
{prefix}/hostvars/{host}/{key}
Example:
/ansible/hostvars/host1/foo
## Host group membership
{prefix}/hosts/{group}/{host}
Example:
/ansible/hosts/group1/host1
## Group children
{prefix}/groups/{parent}/{child}
Example:
/ansible/groups/group1/group2
'''
import sys
import os
import argparse
import re
from time import time
import ConfigParser
try :
import json
except ImportError :
import simplejson as json
try :
import etcd
except ImportError :
raise ImportError ("python-etcd library is required" )
class EtcdInventory :
def _empty_inventory (self ):
return { '_meta' : { 'hostvars' : {} } }
def __init__ (self ):
''' Main execution path '''
self .inventory = self ._empty_inventory ()
# Read settings and parse CLI arguments
self .read_settings ()
self .parse_cli_args ()
# Cache
if self .cache_enabled :
if self .args .refresh_cache :
self .refresh_cache ()
elif not self .is_cache_valid ():
self .refresh_cache ()
if self .inventory == self ._empty_inventory ():
self .load_from_cache ()
else :
self .get_inventory ()
# Data to print
if self .args .host :
data_to_print = self .get_host_info ()
elif self .args .list :
data_to_print = self .json_format_dict (self .inventory , True )
print data_to_print
def get_host_info (self ):
''' Get the hostvars for the given --host arg '''
host = self .args .host
hostvars = self .inventory ['_meta' ]['hostvars' ]
if host in hostvars :
return self .json_format_dict (hostvars [host ],True )
return self .json_format_dict ({}, True )
def parse_cli_args (self ):
''' Command line argument processing '''
parser = argparse .ArgumentParser (description = 'Produce an Ansible Inventory file based on etcd' )
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 etcd (default: False - use cache files)' )
self .args = parser .parse_args ()
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 :
return True
return False
def read_settings (self ):
''' Reads the settings from the etcd.ini file '''
config = ConfigParser .SafeConfigParser ()
etcd_default_ini_path = os .path .join (os .path .dirname (os .path .realpath (__file__ )), 'etcd.ini' )
etcd_default_cache_path = os .path .join (os .path .dirname (os .path .realpath (__file__ )), 'etcd.cache' )
etcd_ini_path = os .environ .get ('ETCD_INI_PATH' , etcd_default_ini_path )
config .read (etcd_ini_path )
# Some sensible defaults
self .prefix = '/ansible'
self .host = 'localhost'
self .port = 4001
self .proto = 'http'
self .ca_cert = None
self .cert = None
self .cache_max_age = 300
self .cache_enabled = True
self .cache_dir = os .path .expanduser ('~/.ansible/tmp' )
secure = False
# Connection to etcd
if config .has_option ('etcd' ,'host' ):
self .host = config .get ('etcd' ,'host' )
if config .has_option ('etcd' ,'port' ):
self .port = config .getint ('etcd' ,'port' )
if config .has_option ('etcd' ,'secure' ):
secure = config .getboolean ('etcd' ,'secure' )
if secure :
self .proto = 'https'
if config .has_option ('etcd' ,'ca_cert' ):
self .ca_cert = config .get ('etcd' ,'ca_cert' )
if config .has_option ('etcd' ,'client_cert' ) and config .has_option ('etcd' ,'client_key' ):
self .cert = (config .get ('etcd' ,'client_cert' ),config .get ('etcd' ,'client_key' ))
# Cache related
if config .has_option ('cache' ,'enabled' ):
self .cache_enabled = config .getboolean ('cache' ,'enabled' )
if config .has_option ('cache' ,'path' ):
self .cache_dir = os .path .expanduser (config .get ('cache' , 'path' ))
self .cache_path_cache = self .cache_dir + "/ansible-etcd.cache"
if config .has_option ('cache' ,'max_age' ):
self .cache_max_age = config .getint ('cache' , 'max_age' )
def add_group (self ,group ):
if group not in self .inventory :
self .inventory [group ] = { 'hosts' : [], 'vars' : {}, 'children' : [] }
def get_inventory (self ):
''' Get inventory from etcd '''
client = etcd .Client (host = self .host ,port = self .port ,protocol = self .proto ,ca_cert = self .ca_cert ,cert = self .cert )
try :
inventory = client .read (self .prefix ,recursive = True )
except KeyError as e :
raise Exception ("Unable read inventory; " + str (e ))
except Exception as e :
msg = str (e )
if "alert bad certificate" in msg :
raise Exception ("Make sure client_cert and client_key are set correctly; " + msg )
if "No JSON object could be decoded" in msg :
raise Exception ("Double check your secure = true setting; " + msg )
if "No more machines in the cluster" in msg :
raise Exception ("Are your host and port correct?; " + msg )
raise
self .inventory = self ._empty_inventory ()
for i in inventory .leaves :
prefix = self .prefix + '/'
relpath = i .key [len (prefix ):]
path_parts = relpath .split ('/' )
t = path_parts [0 ]
if len (path_parts ) != 3 :
continue
# Host Variables
if t == 'hostvars' :
_ ,host ,key = path_parts
if host not in self .inventory ['_meta' ]['hostvars' ]:
self .inventory ['_meta' ]['hostvars' ][host ] = {}
self .inventory ['_meta' ]['hostvars' ][host ][key ] = i .value
## Add group variables
if t == 'groupvars' :
_ ,group ,key = path_parts
self .add_group (group )
self .inventory [group ]['vars' ][key ] = i .value
# Add host to group
if t == 'hosts' :
_ ,group ,host = path_parts
self .add_group (group )
self .inventory [group ]['hosts' ].append (host )
# Group children
if t == 'groups' :
_ ,group ,child = path_parts
self .add_group (group )
self .inventory [group ]['children' ].append (child )
def refresh_cache (self ):
''' Get inventory from etcd and refresh the cache files '''
self .get_inventory ()
if not os .path .exists (self .cache_dir ):
os .makedirs (self .cache_dir )
json_data = self .json_format_dict (self .inventory , True )
cache = open (self .cache_path_cache , 'w' )
cache .write (json_data )
cache .close ()
def load_from_cache (self ):
''' Reads the cached inventory file sets self.inventory '''
cache = open (self .cache_path_cache , 'r' )
json_inventory = cache .read ()
self .inventory = json .loads (json_inventory )
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 )
EtcdInventory ()
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