Added module haproxy, to handle enable/disable backend server with shutdown_sessions feature in haproxy.

net_infrastructure/haproxy.py

@@ -0,0 +1,391 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# (c) 2014, Ravi Bhure <ravibhure@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/>.
+
+DOCUMENTATION = '''
+---
+module: haproxy
+short_description: An Ansible module to handle actions enable/disable server and set/get weight from haproxy using socket commands.
+description:
+    - Enable/Diable Haproxy Backend Server,
+    - Get/Set weight of Haproxy Backend Server,
+      using haproxy socket commands - http://haproxy.1wt.eu
+notes:
+    - "enable or disable or set weight commands are restricted and can only be issued on sockets configured for level 'admin', "
+    - "Check - http://haproxy.1wt.eu/download/1.5/doc/configuration.txt, "
+    - "Example: 'stats socket /var/run/haproxy.sock level admin'"
+options:
+  action:
+    description:
+      - Action to take.
+    required: true
+    default: null
+    choices: [ "enable_server", "disable_server", "get_weight", "set_weight" ]
+  host:
+    description:
+      - Host (backend) to operate in Haproxy.
+    required: true
+    default: null
+  socket:
+    description:
+      - Haproxy socket file name with path.
+    required: false
+    default: /var/run/haproxy.sock
+  backend:
+    description:
+      - Name of the haproxy backend pool.
+        Required, else auto-detection applied.
+    required: false
+    default: auto-detected
+  weight:
+    description:
+      - The value passed in argument. If the value ends with the '%' sign, then the new weight will be relative to the initially cnfigured weight. Relative weights are only permitted between 0 and 100% and absolute weights are permitted between 0 and 256.
+    required: false
+    default: null
+  shutdown_sessions:
+    description:
+      - When disabling server, immediately terminate all the sessions attached to the specified server. This can be used to terminate long-running sessions after a server is put into maintenance mode, for instance.
+    required: false
+    default: false
+'''
+
+EXAMPLES = '''
+# disable backend server in 'www' backend
+- haproxy: action=disable_server host={{ inventory_hostname }} backend=www
+
+# disable backend server without backend name (applied to all)
+- haproxy: action=disable_server host={{ inventory_hostname }}
+
+# disable server, provide socket file
+- haproxy: action=disable_server host={{ inventory_hostname }} socket=/var/run/haproxy.sock backend=www
+
+# disable backend server in 'www' backend and drop open sessions to it
+- haproxy: action=disable_server host={{ inventory_hostname }} backend=www shutdown_sessions=true
+
+# enable backend server in 'www' backend
+- haproxy: action=enable_server host={{ inventory_hostname }} backend=www
+
+# report a server's current weight in 'www' backend
+- haproxy: action=get_weight host={{ inventory_hostname }} backend=www
+
+# change a server's current weight in 'www' backend
+- haproxy: action=set_weight host={{ inventory_hostname }} backend=www weight=10
+
+author: Ravi Bhure <ravibhure@gmail.com>
+version_added: "1.6"
+'''
+
+import logging
+import socket
+import re
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_SOCKET_LOCATION="/var/run/haproxy.sock"
+RECV_SIZE = 1024
+
+def main():
+    ACTION_CHOICES = [
+        'enable_server',
+        'disable_server',
+        'get_weight',
+        'set_weight'
+        ]
+
+    # load ansible module object
+    module = AnsibleModule(
+        argument_spec = dict(
+            action = dict(required=True, default=None, choices=ACTION_CHOICES),
+            host=dict(required=True, default=None),
+            backend=dict(required=False, default=None),
+            weight=dict(required=False, default=None),
+            socket = dict(required=False, default=DEFAULT_SOCKET_LOCATION),
+            shutdown_sessions=dict(required=False, default=False),
+        ),
+    )
+    action = module.params['action']
+    host = module.params['host']
+    backend = module.params['backend']
+    weight = module.params['weight']
+    socket = module.params['socket']
+    shutdown_sessions = module.params['shutdown_sessions']
+
+    ##################################################################
+    # Required args per action:
+    # (enable/disable)_server = (host)
+    #
+    # AnsibleModule will verify most stuff, we need to verify
+    # 'socket' manually.
+
+    ##################################################################
+
+    if action in ['enable_server', 'disable_server', 'get_weight', 'set_weight']:
+        if not host:
+            module.fail_json(msg='no host specified for action requiring one')
+    ##################################################################
+    if not socket:
+        module.fail_json('unable to locate haproxy.sock')
+
+    ##################################################################
+    supports_check_mode=True,
+    required_one_of=[['action', 'host']]
+
+    ansible_haproxy = HAProxy(module, **module.params)
+    if module.check_mode:
+        module.exit_json(changed=True)
+    else:
+        ansible_haproxy.act()
+    ##################################################################
+
+######################################################################
+class TimeoutException(Exception):
+  pass
+
+class HAProxy(object):
+    """
+    Used for communicating with HAProxy through its local UNIX socket interface.
+    Perform common tasks in Haproxy related to enable server and
+    disable server.
+
+    The complete set of external commands Haproxy handles is documented
+    on their website:
+
+    http://haproxy.1wt.eu/download/1.5/doc/configuration.txt#Unix Socket commands
+    """
+
+    def __init__(self, module, **kwargs):
+        self.module = module
+        self.action = kwargs['action']
+        self.host = kwargs['host']
+        self.backend = kwargs['backend']
+        self.weight = kwargs['weight']
+        self.socket = kwargs['socket']
+        self.shutdown_sessions = kwargs['shutdown_sessions']
+
+        self.command_results = []
+
+    def execute(self, cmd, timeout=200):
+        """
+        Executes a HAProxy command by sending a message to a HAProxy's local
+        UNIX socket and waiting up to 'timeout' milliseconds for the response.
+        """
+
+        buffer = ""
+
+
+        self.client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        self.client.connect(self.socket)
+        self.client.sendall('%s\n' % cmd)
+        result = ''
+        buf = ''
+        buf = self.client.recv(RECV_SIZE)
+        while buf:
+          result += buf
+          buf = self.client.recv(RECV_SIZE)
+	self.command_results = result.strip()
+        self.client.close()
+        return result
+
+    def enable_server(self, host, backend):
+        """
+        Enables backend server for a particular backend.
+
+        enable server <backend>/<server>
+          If the server was previously marked as DOWN for maintenance, this marks the
+          server UP and checks are re-enabled.
+
+          Both the backend and the server may be specified either by their name or by
+          their numeric ID, prefixed with a sharp ('#').
+
+          This command is restricted and can only be issued on sockets configured for
+          level "admin".
+
+        Syntax: enable server <pxname>/<svname>
+        """
+        svname = host
+        if self.backend is None:
+          output = self.execute('show stat')
+          #sanitize and make a list of lines
+          output = output.lstrip('# ').strip()
+          output = output.split('\n')
+          result = output
+
+          for line in result:
+            if 'BACKEND' in line:
+              result =  line.split(',')[0]
+              pxname = result
+              cmd = "enable server %s/%s" % (pxname, svname)
+              self.execute(cmd)
+
+        else:
+            pxname = backend
+            cmd = "enable server %s/%s" % (pxname, svname)
+            self.execute(cmd)
+
+    def disable_server(self, host, backend, shutdown_sessions):
+        """
+        Disable backend server for a particular backend.
+
+        disable server <backend>/<server>
+          Mark the server DOWN for maintenance. In this mode, no more checks will be
+          performed on the server until it leaves maintenance.
+          If the server is tracked by other servers, those servers will be set to DOWN
+          during the maintenance.
+
+          In the statistics page, a server DOWN for maintenance will appear with a
+          "MAINT" status, its tracking servers with the "MAINT(via)" one.
+
+          Both the backend and the server may be specified either by their name or by
+          their numeric ID, prefixed with a sharp ('#').
+
+          This command is restricted and can only be issued on sockets configured for
+          level "admin".
+
+        Syntax: disable server <pxname>/<svname>
+        """
+        svname = host
+        if self.backend is None:
+          output = self.execute('show stat')
+          #sanitize and make a list of lines
+          output = output.lstrip('# ').strip()
+          output = output.split('\n')
+          result = output
+
+          for line in result:
+            if 'BACKEND' in line:
+              result =  line.split(',')[0]
+              pxname = result
+              cmd = "disable server %s/%s" % (pxname, svname)
+              if shutdown_sessions:
+                cmd += "; shutdown sessions server %s/%s" % (pxname, svname)
+              self.execute(cmd)
+
+        else:
+            pxname = backend
+            cmd = "disable server %s/%s" % (pxname, svname)
+            if shutdown_sessions:
+              cmd += "; shutdown sessions server %s/%s" % (pxname, svname)
+            self.execute(cmd)
+
+    def get_weight(self, host, backend):
+        """
+        Report a server's current weight.
+
+        get weight <backend>/<server>
+          Report the current weight and the initial weight of server <server> in
+          backend <backend> or an error if either doesn't exist. The initial weight is
+          the one that appears in the configuration file. Both are normally equal
+          unless the current weight has been changed. Both the backend and the server
+          may be specified either by their name or by their numeric ID, prefixed with a
+          sharp ('#').
+
+        Syntax: get weight <pxname>/<svname>
+        """
+        svname = host
+        if self.backend is None:
+          output = self.execute('show stat')
+          #sanitize and make a list of lines
+          output = output.lstrip('# ').strip()
+          output = output.split('\n')
+          result = output
+
+          for line in result:
+            if 'BACKEND' in line:
+              result =  line.split(',')[0]
+              pxname = result
+              cmd = "get weight %s/%s" % (pxname, svname)
+              self.execute(cmd)
+
+        else:
+            pxname = backend
+            cmd = "get weight %s/%s" % (pxname, svname)
+            self.execute(cmd)
+
+    def set_weight(self, host, backend, weight):
+        """
+        Change a server's current weight.
+
+        set weight <backend>/<server> <weight>[%]
+          Change a server's weight to the value passed in argument. If the value ends
+          with the '%' sign, then the new weight will be relative to the initially
+          configured weight. Relative weights are only permitted between 0 and 100%,
+          and absolute weights are permitted between 0 and 256. Servers which are part
+          of a farm running a static load-balancing algorithm have stricter limitations
+          because the weight cannot change once set. Thus for these servers, the only
+          accepted values are 0 and 100% (or 0 and the initial weight). Changes take
+          effect immediately, though certain LB algorithms require a certain amount of
+          requests to consider changes. A typical usage of this command is to disable
+          a server during an update by setting its weight to zero, then to enable it
+          again after the update by setting it back to 100%. This command is restricted
+          and can only be issued on sockets configured for level "admin". Both the
+          backend and the server may be specified either by their name or by their
+          numeric ID, prefixed with a sharp ('#').
+
+        Syntax: set weight <pxname>/<svname>
+        """
+        svname = host
+        weight = weight
+        if self.backend is None:
+          output = self.execute('show stat')
+          #sanitize and make a list of lines
+          output = output.lstrip('# ').strip()
+          output = output.split('\n')
+          result = output
+
+          for line in result:
+            if 'BACKEND' in line:
+              result =  line.split(',')[0]
+              pxname = result
+              cmd = "set weight %s/%s %s" % (pxname, svname, weight)
+              self.execute(cmd)
+
+        else:
+            pxname = backend
+            cmd = "set weight %s/%s %s" % (pxname, svname, weight)
+            self.execute(cmd)
+
+    def act(self):
+        """
+        Figure out what you want to do from ansible, and then do the
+        needful (at the earliest).
+        """
+        # toggle enable/disbale server
+        if self.action == 'enable_server':
+            self.enable_server(self.host, self.backend)
+
+        elif self.action == 'disable_server':
+            self.disable_server(self.host, self.backend, self.shutdown_sessions)
+
+        # toggle get/set weight
+        elif self.action == 'get_weight':
+            self.get_weight(self.host, self.backend)
+
+        elif self.action == 'set_weight':
+            self.set_weight(self.host, self.backend, self.weight)
+        # wtf?
+        else:
+            self.module.fail_json(msg="unknown action specified: '%s'" % \
+                                      self.action)
+
+        self.module.exit_json(stdout=self.command_results, changed=True)
+
+# import module snippets
+from ansible.module_utils.basic import *
+
+main()