#!/usr/bin/python
# -*- encoding: utf-8; py-indent-offset: 4 -*-
# +------------------------------------------------------------------+
# |             ____ _               _        __  __ _  __           |
# |            / ___| |__   ___  ___| | __   |  \/  | |/ /           |
# |           | |   | '_ \ / _ \/ __| |/ /   | |\/| | ' /            |
# |           | |___| | | |  __/ (__|   <    | |  | | . \            |
# |            \____|_| |_|\___|\___|_|\_\___|_|  |_|_|\_\           |
# |                                                                  |
# | Copyright Mathias Kettner 2014             mk@mathias-kettner.de |
# +------------------------------------------------------------------+
#
# This file is part of Check_MK.
# The official homepage is at http://mathias-kettner.de/check_mk.
#
# check_mk 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 in version 2.  check_mk is  distributed
# in the hope that it will be useful, but WITHOUT ANY WARRANTY;  with-
# out even the implied warranty of  MERCHANTABILITY  or  FITNESS FOR A
# PARTICULAR PURPOSE. See the  GNU General Public License for more de-
# tails. You should have  received  a copy of the  GNU  General Public
# License along with GNU Make; see the file  COPYING.  If  not,  write
# to the Free Software Foundation, Inc., 51 Franklin St,  Fifth Floor,
# Boston, MA 02110-1301 USA.

# Check_MK-Agent-Plugin - Apache Server Status
#
# Fetches the server-status page from detected or configured apache
# processes to gather status information about this apache process.
#
# To make this agent plugin work you have to load the status_module
# into your apache process. It is also needed to enable the "server-status"
# handler below the URL "/server-status".
#
# By default this plugin tries to detect all locally running apache processes
# and to monitor them. If this is not good for your environment you might
# create an apache_status.cfg file in MK_CONFDIR and populate the servers
# list to prevent executing the detection mechanism.
#
# It is also possible to override or extend the ssl_ports variable to make the
# check contact other ports than 443 with HTTPS requests.

import os, sys, urllib2, re, socket

config_dir = os.getenv("MK_CONFDIR", "/etc/check_mk")
config_file = config_dir + "/apache_status.conf"

if not os.path.exists(config_file):
    config_file = config_dir + "/apache_status.cfg"

# We have to deal with socket timeouts. Python > 2.6
# supports timeout parameter for the urllib2.urlopen method
# but we are on a python 2.5 system here which seem to use the
# default socket timeout. We are local here so  set it to 1 second.
socket.setdefaulttimeout(5.0)

# None or list of (proto, ipaddress, port) tuples.
# proto is 'http' or 'https'
servers = None
ssl_ports = [ 443, ]

if os.path.exists(config_file):
    execfile(config_file)


def try_detect_servers():
    results = []

    for line in os.popen('netstat -tlnp 2>/dev/null').readlines():
        parts = line.split()
        # Skip lines with wrong format
        if len(parts) < 7 or '/' not in parts[6]:
            continue

        pid, proc = parts[6].split('/', 1)
        to_replace = re.compile('^.*/')
        proc = to_replace.sub('', proc)

        procs = [ 'apache2', 'httpd', 'httpd2-prefork', 'httpd2-worker', 'httpd.worker', 'fcgi-pm' ]
        # the pid/proc field length is limited to 19 chars. Thus in case of
        # long PIDs, the process names are stripped of by that length.
        # Workaround this problem here
        procs = [ p[:19 - len(pid) - 1] for p in procs ]

        # Skip unwanted processes
        if proc not in procs:
            continue

        address, port = parts[3].rsplit(':', 1)
        port = int(port)

        # Use localhost when listening globally
        if address == '0.0.0.0':
            address = '127.0.0.1'
        elif address == '::':
            address = '[::1]'
        elif ':' in address:
            address = '[%s]' % address

        # Switch protocol if port is SSL port. In case you use SSL on another
        # port you would have to change/extend the ssl_port list
        if port in ssl_ports:
            proto = 'https'
        else:
            proto = 'http'

        results.append((proto, address, port))

    return results


if servers is None:
    servers = try_detect_servers()


if not servers:
    sys.exit(0)


sys.stdout.write('<<<apache_status>>>\n')
for server in servers:
    if isinstance(server, tuple):
        proto, address, port = server
        page = 'server-status'
    else:
        proto = server['protocol']
        address = server['address']
        port = server['port']
        page = server.get('page', 'server-status')

    portspec = port and ":%d" % port or ""

    try:
        url = '%s://%s%s/%s?auto' % (proto, address, portspec, page)
        # Try to fetch the status page for each server
        try:
            request = urllib2.Request(url, headers={"Accept" : "text/plain"})
            fd = urllib2.urlopen(request)
        except urllib2.URLError, e:
            if 'unknown protocol' in str(e):
                # HACK: workaround misconfigurations where port 443 is used for
                # serving non ssl secured http
                url = 'http://%s%s/server-status?auto' % (address, portspec)
                fd = urllib2.urlopen(url)
            else:
                raise
        except Exception, e:
            if 'doesn\'t match' in str(e):
                # HACK: workaround if SSL port is found and localhost is using
                # SSL connections but certificate does not match
                portspec = ':80'
                url = 'http://%s%s/server-status?auto' % (address, portspec)
                fd = urllib2.urlopen(url)
            else:
                raise

        for line in fd.read().split('\n'):
            if not line.strip():
                continue
            if line.lstrip()[0] == '<':
                # Seems to be html output. Skip this server.
                break

            sys.stdout.write("%s %s %s\n" % (address, port, line))
    except urllib2.HTTPError, e:
        sys.stderr.write('HTTP-Error (%s%s): %s %s\n' % (address, portspec, e.code, e))

    except Exception, e:
        sys.stderr.write('Exception (%s%s): %s\n' % (address, portspec, e))