#!/usr/bin/python # -*- coding: utf-8 -*- # Copyright: (c) 2014, Ravi Bhure <ravibhure@gmail.com> # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt) from __future__ import absolute_import, division, print_function __metaclass__ = type DOCUMENTATION = r''' --- module: haproxy short_description: Enable, disable, and set weights for HAProxy backend servers using socket commands author: - Ravi Bhure (@ravibhure) description: - Enable, disable, drain and set weights for HAProxy backend servers using socket commands. notes: - Enable, disable and drain commands are restricted and can only be issued on sockets configured for level 'admin'. For example, you can add the line 'stats socket /var/run/haproxy.sock level admin' to the general section of haproxy.cfg. See U(http://haproxy.1wt.eu/download/1.5/doc/configuration.txt). - Depends on netcat (nc) being available; you need to install the appropriate package for your operating system before this module can be used. options: backend: description: - Name of the HAProxy backend pool. - If this parameter is unset, it will be auto-detected. type: str drain: description: - Wait until the server has no active connections or until the timeout determined by wait_interval and wait_retries is reached. - Continue only after the status changes to 'MAINT'. - This overrides the shutdown_sessions option. type: bool default: false host: description: - Name of the backend host to change. type: str required: true shutdown_sessions: description: - When disabling a 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. Overridden by the drain option. type: bool default: no socket: description: - Path to the HAProxy socket file. type: path default: /var/run/haproxy.sock state: description: - Desired state of the provided backend host. - Note that C(drain) state was added in version 2.4. - It is supported only by HAProxy version 1.5 or later, - When used on versions < 1.5, it will be ignored. type: str required: true choices: [ disabled, drain, enabled ] agent: description: - Disable/enable agent checks (depending on I(state) value). type: bool default: no version_added: 1.0.0 health: description: - Disable/enable health checks (depending on I(state) value). type: bool default: no version_added: "1.0.0" fail_on_not_found: description: - Fail whenever trying to enable/disable a backend host that does not exist type: bool default: no wait: description: - Wait until the server reports a status of 'UP' when C(state=enabled), status of 'MAINT' when C(state=disabled) or status of 'DRAIN' when C(state=drain) type: bool default: no wait_interval: description: - Number of seconds to wait between retries. type: int default: 5 wait_retries: description: - Number of times to check for status after changing the state. type: int default: 25 weight: description: - 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. type: str ''' EXAMPLES = r''' - name: Disable server in 'www' backend pool community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' backend: www - name: Disable server in 'www' backend pool, also stop health/agent checks community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' health: yes agent: yes - name: Disable server without backend pool name (apply to all available backend pool) community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' - name: Disable server, provide socket file community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' socket: /var/run/haproxy.sock backend: www - name: Disable server, provide socket file, wait until status reports in maintenance community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' socket: /var/run/haproxy.sock backend: www wait: yes # Place server in drain mode, providing a socket file. Then check the server's # status every minute to see if it changes to maintenance mode, continuing if it # does in an hour and failing otherwise. - community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' socket: /var/run/haproxy.sock backend: www wait: yes drain: yes wait_interval: 1 wait_retries: 60 - name: Disable backend server in 'www' backend pool and drop open sessions to it community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' backend: www socket: /var/run/haproxy.sock shutdown_sessions: yes - name: Disable server without backend pool name (apply to all available backend pool) but fail when the backend host is not found community.general.haproxy: state: disabled host: '{{ inventory_hostname }}' fail_on_not_found: yes - name: Enable server in 'www' backend pool community.general.haproxy: state: enabled host: '{{ inventory_hostname }}' backend: www - name: Enable server in 'www' backend pool wait until healthy community.general.haproxy: state: enabled host: '{{ inventory_hostname }}' backend: www wait: yes - name: Enable server in 'www' backend pool wait until healthy. Retry 10 times with intervals of 5 seconds to retrieve the health community.general.haproxy: state: enabled host: '{{ inventory_hostname }}' backend: www wait: yes wait_retries: 10 wait_interval: 5 - name: Enable server in 'www' backend pool with change server(s) weight community.general.haproxy: state: enabled host: '{{ inventory_hostname }}' socket: /var/run/haproxy.sock weight: 10 backend: www - name: Set the server in 'www' backend pool to drain mode community.general.haproxy: state: drain host: '{{ inventory_hostname }}' socket: /var/run/haproxy.sock backend: www ''' import csv import socket import time from string import Template from ansible.module_utils.basic import AnsibleModule from ansible.module_utils._text import to_bytes, to_text DEFAULT_SOCKET_LOCATION = "/var/run/haproxy.sock" RECV_SIZE = 1024 ACTION_CHOICES = ['enabled', 'disabled', 'drain'] WAIT_RETRIES = 25 WAIT_INTERVAL = 5 ###################################################################### 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): self.module = module self.state = self.module.params['state'] self.host = self.module.params['host'] self.backend = self.module.params['backend'] self.weight = self.module.params['weight'] self.socket = self.module.params['socket'] self.shutdown_sessions = self.module.params['shutdown_sessions'] self.fail_on_not_found = self.module.params['fail_on_not_found'] self.agent = self.module.params['agent'] self.health = self.module.params['health'] self.wait = self.module.params['wait'] self.wait_retries = self.module.params['wait_retries'] self.wait_interval = self.module.params['wait_interval'] self._drain = self.module.params['drain'] self.command_results = {} def execute(self, cmd, timeout=200, capture_output=True): """ Executes a HAProxy command by sending a message to a HAProxy's local UNIX socket and waiting up to 'timeout' milliseconds for the response. """ self.client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) self.client.connect(self.socket) self.client.sendall(to_bytes('%s\n' % cmd)) result = b'' buf = b'' buf = self.client.recv(RECV_SIZE) while buf: result += buf buf = self.client.recv(RECV_SIZE) result = to_text(result, errors='surrogate_or_strict') if capture_output: self.capture_command_output(cmd, result.strip()) self.client.close() return result def capture_command_output(self, cmd, output): """ Capture the output for a command """ if 'command' not in self.command_results: self.command_results['command'] = [] self.command_results['command'].append(cmd) if 'output' not in self.command_results: self.command_results['output'] = [] self.command_results['output'].append(output) def discover_all_backends(self): """ Discover all entries with svname = 'BACKEND' and return a list of their corresponding pxnames """ data = self.execute('show stat', 200, False).lstrip('# ') r = csv.DictReader(data.splitlines()) return tuple(map(lambda d: d['pxname'], filter(lambda d: d['svname'] == 'BACKEND', r))) def discover_version(self): """ Attempt to extract the haproxy version. Return a tuple containing major and minor version. """ data = self.execute('show info', 200, False) lines = data.splitlines() line = [x for x in lines if 'Version:' in x] try: version_values = line[0].partition(':')[2].strip().split('.', 3) version = (int(version_values[0]), int(version_values[1])) except (ValueError, TypeError, IndexError): version = None return version def execute_for_backends(self, cmd, pxname, svname, wait_for_status=None): """ Run some command on the specified backends. If no backends are provided they will be discovered automatically (all backends) """ # Discover backends if none are given if pxname is None: backends = self.discover_all_backends() else: backends = [pxname] # Run the command for each requested backend for backend in backends: # Fail when backends were not found state = self.get_state_for(backend, svname) if (self.fail_on_not_found) and state is None: self.module.fail_json( msg="The specified backend '%s/%s' was not found!" % (backend, svname)) if state is not None: self.execute(Template(cmd).substitute(pxname=backend, svname=svname)) if self.wait: self.wait_until_status(backend, svname, wait_for_status) def get_state_for(self, pxname, svname): """ Find the state of specific services. When pxname is not set, get all backends for a specific host. Returns a list of dictionaries containing the status and weight for those services. """ data = self.execute('show stat', 200, False).lstrip('# ') r = csv.DictReader(data.splitlines()) state = tuple( map( lambda d: {'status': d['status'], 'weight': d['weight'], 'scur': d['scur']}, filter(lambda d: (pxname is None or d['pxname'] == pxname) and d['svname'] == svname, r) ) ) return state or None def wait_until_status(self, pxname, svname, status): """ Wait for a service to reach the specified status. Try RETRIES times with INTERVAL seconds of sleep in between. If the service has not reached the expected status in that time, the module will fail. If the service was not found, the module will fail. """ for i in range(1, self.wait_retries): state = self.get_state_for(pxname, svname) # We can assume there will only be 1 element in state because both svname and pxname are always set when we get here # When using track we get a status like this: MAINT (via pxname/svname) so we need to do substring matching if status in state[0]['status']: if not self._drain or state[0]['scur'] == '0': return True time.sleep(self.wait_interval) self.module.fail_json(msg="server %s/%s not status '%s' after %d retries. Aborting." % (pxname, svname, status, self.wait_retries)) def enabled(self, host, backend, weight): """ Enabled action, marks server to UP and checks are re-enabled, also supports to get current weight for server (default) and set the weight for haproxy backend server when provides. """ cmd = "get weight $pxname/$svname; enable server $pxname/$svname" if self.agent: cmd += "; enable agent $pxname/$svname" if self.health: cmd += "; enable health $pxname/$svname" if weight: cmd += "; set weight $pxname/$svname %s" % weight self.execute_for_backends(cmd, backend, host, 'UP') def disabled(self, host, backend, shutdown_sessions): """ Disabled action, marks server to DOWN for maintenance. In this mode, no more checks will be performed on the server until it leaves maintenance, also it shutdown sessions while disabling backend host server. """ cmd = "get weight $pxname/$svname" if self.agent: cmd += "; disable agent $pxname/$svname" if self.health: cmd += "; disable health $pxname/$svname" cmd += "; disable server $pxname/$svname" if shutdown_sessions: cmd += "; shutdown sessions server $pxname/$svname" self.execute_for_backends(cmd, backend, host, 'MAINT') def drain(self, host, backend, status='DRAIN'): """ Drain action, sets the server to DRAIN mode. In this mode, the server will not accept any new connections other than those that are accepted via persistence. """ haproxy_version = self.discover_version() # check if haproxy version supports DRAIN state (starting with 1.5) if haproxy_version and (1, 5) <= haproxy_version: cmd = "set server $pxname/$svname state drain" self.execute_for_backends(cmd, backend, host, "DRAIN") if status == "MAINT": self.disabled(host, backend, self.shutdown_sessions) def act(self): """ Figure out what you want to do from ansible, and then do it. """ # Get the state before the run self.command_results['state_before'] = self.get_state_for(self.backend, self.host) # toggle enable/disable server if self.state == 'enabled': self.enabled(self.host, self.backend, self.weight) elif self.state == 'disabled' and self._drain: self.drain(self.host, self.backend, status='MAINT') elif self.state == 'disabled': self.disabled(self.host, self.backend, self.shutdown_sessions) elif self.state == 'drain': self.drain(self.host, self.backend) else: self.module.fail_json(msg="unknown state specified: '%s'" % self.state) # Get the state after the run self.command_results['state_after'] = self.get_state_for(self.backend, self.host) # Report change status self.command_results['changed'] = (self.command_results['state_before'] != self.command_results['state_after']) self.module.exit_json(**self.command_results) def main(): # load ansible module object module = AnsibleModule( argument_spec=dict( state=dict(type='str', required=True, choices=ACTION_CHOICES), host=dict(type='str', required=True), backend=dict(type='str'), weight=dict(type='str'), socket=dict(type='path', default=DEFAULT_SOCKET_LOCATION), shutdown_sessions=dict(type='bool', default=False), fail_on_not_found=dict(type='bool', default=False), health=dict(type='bool', default=False), agent=dict(type='bool', default=False), wait=dict(type='bool', default=False), wait_retries=dict(type='int', default=WAIT_RETRIES), wait_interval=dict(type='int', default=WAIT_INTERVAL), drain=dict(type='bool', default=False), ), ) if not socket: module.fail_json(msg="unable to locate haproxy socket") ansible_haproxy = HAProxy(module) ansible_haproxy.act() if __name__ == '__main__': main()