consul_io.py

#!/usr/bin/env python

#
# (c) 2015, Steve Gargan <steve.gargan@gmail.com>
#
# 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/>.

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

'''
Consul.io inventory script (http://consul.io)
======================================

Generates Ansible inventory from nodes in a Consul cluster. This script will
group nodes by:
 - datacenter,
 - registered service
 - service tags
 - service status
 - values from the k/v store

This script can be run with the switches
--list as expected groups all the nodes in all datacenters
--datacenter, to restrict the nodes to a single datacenter
--host to restrict the inventory to a single named node. (requires datacenter config)

The configuration for this plugin is read from a consul.ini file located in the
same directory as this inventory script. All config options in the config file
are optional except the host and port, which must point to a valid agent or
server running the http api. For more information on enabling the endpoint see.

http://www.consul.io/docs/agent/options.html

Other options include:

'datacenter':

which restricts the included nodes to those from the given datacenter

'domain':

if specified then the inventory will generate domain names that will resolve
via Consul's inbuilt DNS. The name is derived from the node name, datacenter
and domain <node_name>.node.<datacenter>.<domain>. Note that you will need to
have consul hooked into your DNS server for these to resolve. See the consul
DNS docs for more info.

which restricts the included nodes to those from the given datacenter

'servers_suffix':

defining the a suffix to add to the service name when creating the service
group. e.g Service name of 'redis' and a suffix of '_servers' will add
each nodes address to the group name 'redis_servers'. No suffix is added
if this is not set

'tags':

boolean flag defining if service tags should be used to create Inventory
groups e.g. an nginx service with the tags ['master', 'v1'] will create
groups nginx_master and nginx_v1 to which the node running the service
will be added. No tag groups are created if this is missing.

'token':

ACL token to use to authorize access to the key value store. May be required
to retrieve the kv_groups and kv_metadata based on your consul configuration.

'kv_groups':

This is used to lookup groups for a node in the key value store. It specifies a
path to which each discovered node's name will be added to create a key to query
the key/value store. There it expects to find a comma separated list of group
names to which the node should be added e.g. if the inventory contains
'nyc-web-1' and kv_groups = 'ansible/groups' then the key
'v1/kv/ansible/groups/nyc-web-1' will be queried for a group list. If this query
 returned 'test,honeypot' then the node address to both groups.

'kv_metadata':

kv_metadata is used to lookup metadata for each discovered node. Like kv_groups
above it is used to build a path to lookup in the kv store where it expects to
find a json dictionary of metadata entries. If found, each key/value pair in the
dictionary is added to the metadata for the node.

'availability':

if true then availability groups will be created for each service. The node will
be added to one of the groups based on the health status of the service. The
group name is derived from the service name and the configurable availability
suffixes

'available_suffix':

suffix that should be appended to the service availability groups for available
services e.g. if the suffix is '_up' and the service is nginx, then nodes with
healthy nginx services will be added to the nginix_up group. Defaults to
'_available'

'unavailable_suffix':

as above but for unhealthy services, defaults to '_unavailable'

Note that if the inventory discovers an 'ssh' service running on a node it will
register the port as ansible_ssh_port in the node's metadata and this port will
be used to access the machine.
```

'''

import os
import re
import argparse
from time import time
import sys
import ConfigParser
import urllib, urllib2, base64

try:
  import json
except ImportError:
  import simplejson as json

try:
  import consul
except ImportError, e:
  print """failed=True msg='python-consul required for this module. see
  http://python-consul.readthedocs.org/en/latest/#installation'"""
  sys.exit(1)



class ConsulInventory(object):

  def __init__(self):
    ''' Create an inventory based on the catalog of nodes and services
    registered in a consul cluster'''
    self.node_metadata = {}
    self.nodes = {}
    self.nodes_by_service = {}
    self.nodes_by_tag = {}
    self.nodes_by_datacenter = {}
    self.nodes_by_kv = {}
    self.nodes_by_availability = {}
    self.current_dc = None

    config = ConsulConfig()
    self.config = config

    self.consul_api = config.get_consul_api()

    if config.has_config('datacenter'):
      if config.has_config('host'):
        self.load_data_for_node(config.host, config.datacenter)
      else:
        self.load_data_for_datacenter(config.datacenter)
    else:
      self.load_all_data_consul()

    self.combine_all_results()
    print json.dumps(self.inventory, sort_keys=True, indent=2)

  def load_all_data_consul(self):
    ''' cycle through each of the datacenters in the consul catalog and process
        the nodes in each '''
    self.datacenters = self.consul_api.catalog.datacenters()
    for datacenter in self.datacenters:
      self.current_dc = datacenter
      self.load_data_for_datacenter(datacenter)


  def load_availability_groups(self, node, datacenter):
    '''check the health of each service on a node and add add the node to either
    an 'available' or 'unavailable' grouping. The suffix for each group can be
    controlled from the config'''
    if self.config.has_config('availability'):
      for service_name, service in node['Services'].iteritems():
        for node in self.consul_api.health.service(service_name)[1]:
            for check in node['Checks']:
                if check['ServiceName'] == service_name:
                      ok = 'passing' == check['Status']
                      if ok:
                        suffix = self.config.get_availability_suffix(
                                    'available_suffix', '_available')
                      else:
                        suffix = self.config.get_availability_suffix(
                                    'unavailable_suffix', '_unavailable')
                      self.add_node_to_map(self.nodes_by_availability,
                                            service_name + suffix, node['Node'])


  def load_data_for_datacenter(self, datacenter):
    '''processes all the nodes in a particular datacenter'''
    index, nodes = self.consul_api.catalog.nodes(dc=datacenter)
    for node in nodes:
      self.add_node_to_map(self.nodes_by_datacenter, datacenter, node)
      self.load_data_for_node(node['Node'], datacenter)

  def load_data_for_node(self, node, datacenter):
    '''loads the data for a sinle node adding it to various groups based on
    metadata retrieved from the kv store and service availability'''

    index, node_data = self.consul_api.catalog.node(node, dc=datacenter)
    node = node_data['Node']
    self.add_node_to_map(self.nodes, 'all', node)
    self.add_metadata(node_data, "consul_datacenter", datacenter)
    self.add_metadata(node_data, "consul_nodename", node['Node'])

    self.load_groups_from_kv(node_data)
    self.load_node_metadata_from_kv(node_data)
    self.load_availability_groups(node_data, datacenter)

    for name, service in node_data['Services'].items():
      self.load_data_from_service(name, service, node_data)

  def load_node_metadata_from_kv(self, node_data):
    ''' load the json dict at the metadata path defined by the kv_metadata value
        and the node name add each entry in the dictionary to the the node's
        metadata '''
    node = node_data['Node']
    if  self.config.has_config('kv_metadata'):
      key = "%s/%s/%s" % (self.config.kv_metadata, self.current_dc, node['Node'])
      index, metadata = self.consul_api.kv.get(key)
      if metadata and metadata['Value']:
        try:
            metadata = json.loads(metadata['Value'])
            for k,v in metadata.items():
              self.add_metadata(node_data, k, v)
        except:
            pass

  def load_groups_from_kv(self, node_data):
    ''' load the comma separated list of groups at the path defined by the
        kv_groups config value and the node name add the node address to each
        group found '''
    node = node_data['Node']
    if  self.config.has_config('kv_groups'):
      key = "%s/%s/%s" % (self.config.kv_groups, self.current_dc, node['Node'])
      index, groups = self.consul_api.kv.get(key)
      if groups and groups['Value']:
        for group in groups['Value'].split(','):
          self.add_node_to_map(self.nodes_by_kv, group.strip(), node)

  def load_data_from_service(self, service_name, service, node_data):
    '''process a service registered on a node, adding the node to a group with
    the service name. Each service tag is extracted and the node is added to a
    tag grouping also'''
    self.add_metadata(node_data, "consul_services", service_name, True)

    if self.is_service("ssh", service_name):
      self.add_metadata(node_data, "ansible_ssh_port", service['Port'])

    if self.config.has_config('servers_suffix'):
      service_name = service_name + self.config.servers_suffix

    self.add_node_to_map(self.nodes_by_service, service_name, node_data['Node'])
    self.extract_groups_from_tags(service_name, service, node_data)

  def is_service(self, target, name):
    return name and (name.lower() == target.lower())

  def extract_groups_from_tags(self, service_name, service, node_data):
    '''iterates each service tag and adds the node to groups derived from the
    service and tag names e.g. nginx_master'''
    if self.config.has_config('tags') and service['Tags']:
      tags = service['Tags']
      self.add_metadata(node_data, "consul_%s_tags" % service_name, tags)
      for tag in service['Tags']:
        tagname = service_name +'_'+tag
        self.add_node_to_map(self.nodes_by_tag, tagname, node_data['Node'])

  def combine_all_results(self):
    '''prunes and sorts all groupings for combination into the final map'''
    self.inventory = {"_meta": { "hostvars" : self.node_metadata}}
    groupings = [self.nodes, self.nodes_by_datacenter, self.nodes_by_service,
                self.nodes_by_tag, self.nodes_by_kv, self.nodes_by_availability]
    for grouping in groupings:
      for name, addresses in grouping.items():
        self.inventory[name] = sorted(list(set(addresses)))

  def add_metadata(self, node_data, key, value, is_list = False):
    ''' Pushed an element onto a metadata dict for the node, creating
        the dict if it doesn't exist '''
    key = self.to_safe(key)
    node = self.get_inventory_name(node_data['Node'])

    if node in self.node_metadata:
      metadata = self.node_metadata[node]
    else:
      metadata = {}
      self.node_metadata[node] = metadata
    if is_list:
      self.push(metadata, key, value)
    else:
      metadata[key] = value

  def get_inventory_name(self, node_data):
      '''return the ip or a node name that can be looked up in consul's dns'''
      domain = self.config.domain
      if domain:
          node_name = node_data['Node']
          if self.current_dc:
              return '%s.node.%s.%s' % ( node_name, self.current_dc, domain)
          else:
              return '%s.node.%s' % ( node_name, domain)
      else:
          return node_data['Address']

  def add_node_to_map(self, map, name, node):
      self.push(map, name, self.get_inventory_name(node))


  def push(self, my_dict, key, element):
    ''' Pushed an element onto an array that may not have been defined in the
        dict '''
    key = self.to_safe(key)
    if key in my_dict:
      my_dict[key].append(element)
    else:
      my_dict[key] = [element]

  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 sanitize_dict(self, d):

    new_dict = {}
    for k, v in d.items():
      if v != None:
        new_dict[self.to_safe(str(k))] = self.to_safe(str(v))
    return new_dict

  def sanitize_list(self, seq):
    new_seq = []
    for d in seq:
      new_seq.append(self.sanitize_dict(d))
    return new_seq


class ConsulConfig(dict):

  def __init__(self):
    self.read_settings()
    self.read_cli_args()

  def has_config(self, name):
    if hasattr(self, name):
      return getattr(self, name)
    else:
      return False

  def read_settings(self):
    ''' Reads the settings from the consul.ini file '''
    config = ConfigParser.SafeConfigParser()
    config.read(os.path.dirname(os.path.realpath(__file__)) + '/consul.ini')

    config_options = ['host', 'token', 'datacenter', 'servers_suffix',
                      'tags', 'kv_metadata', 'kv_groups', 'availability',
                      'unavailable_suffix', 'available_suffix', 'url',
                      'domain']
    for option in config_options:
      value = None
      if config.has_option('consul', option):
          value = config.get('consul', option)
      setattr(self, option, value)

  def read_cli_args(self):
    ''' Command line argument processing '''
    parser = argparse.ArgumentParser(description=
        'Produce an Ansible Inventory file based nodes in a Consul cluster')

    parser.add_argument('--list', action='store_true',
        help='Get all inventory variables from all nodes in the consul cluster')
    parser.add_argument('--host', action='store',
        help='Get all inventory variables about a specific consul node, \
              requires datacenter set in consul.ini.')
    parser.add_argument('--datacenter', action='store',
        help='Get all inventory about a specific consul datacenter')

    args = parser.parse_args()
    arg_names = ['host', 'datacenter']

    for arg in arg_names:
      if getattr(args, arg):
        setattr(self, arg, getattr(args, arg))

  def get_availability_suffix(self, suffix, default):
      if self.has_config(suffix):
        return self.has_config(suffix)
      return default


  def get_consul_api(self):
      '''get an instance of the api based on the supplied configuration'''
      host = 'localhost'
      port =  8500
      token = None

      if hasattr(self, 'url'):
          from urlparse import urlparse
          o = urlparse(self.url)
          if o.hostname:
              host = o.hostname
          if o.port:
              port = o.port

      if hasattr(self, 'token'):
          token = self.token
          if not token:
              token = 'anonymous'
      return consul.Consul(host=host, port=port, token=token)

ConsulInventory()