mqtt.py

#!/usr/bin/env python
import mosquitto
import ssl
import time
import sys
import os

mqtt_host = 'localhost'
mqtt_port = 1883
mqtt_username = None
mqtt_password = None

check_topic = 'nagios/test'
check_payload = 'PiNG'
max_wait = 4

status = 0
message = ''

nagios_codes = [ 'OK', 'WARNING', 'CRITICAL', 'UNKNOWN' ]

def on_connect(mosq, userdata, rc):
    """
    Upon successfully being connected, we subscribe to the check_topic
    """

    mosq.subscribe(check_topic, 0)

def on_publish(mosq, userdata, mid):
    pass

def on_subscribe(mosq, userdata, mid, granted_qos):
    """
    When the subscription is confirmed, we publish our payload
    on the check_topic. Since we're subscribed to this same topic,
    on_message() will fire when we see that same message
    """

    (res, mid) =  mosq.publish(check_topic, check_payload, qos=2, retain=False)

def on_message(mosq, userdata, msg):
    """
    This is invoked when we get our own message back. Verify that it
    is actually our message and if so, we've completed a round-trip.
    """

    global message
    global status

    if str(msg.payload) == check_payload:
        userdata['have_response'] = True
        status = 0
        elapsed = (time.time() - userdata['start_time'])
        message = "PUB to %s at %s responded in %.2f" % (check_topic, mqtt_host, elapsed)

def on_disconnect(mosq, userdata, rc):
    exitus(1, "Unexpected disconnection. Incorrect credentials?")

def exitus(status=0, message="all is well"):
    """
    Produce a Nagios-compatible single-line message and exit according
    to status
    """

    print "%s - %s" % (nagios_codes[status], message)
    sys.exit(status)

userdata = {
    'have_response' : False,
    'start_time'    : time.time(),
}
mqttc = mosquitto.Mosquitto('nagios-%d' % (os.getpid()), clean_session=True, userdata=userdata)
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_disconnect = on_disconnect
mqttc.on_publish = on_publish
mqttc.on_subscribe = on_subscribe

#mqttc.tls_set('root.ca',
#    cert_reqs=ssl.CERT_REQUIRED,
#    tls_version=1)

#mqttc.tls_set('root.ca', certfile='c1.crt', keyfile='c1.key', cert_reqs=ssl.CERT_REQUIRED, tls_version=3, ciphers=None)
#mqttc.tls_insecure_set(True)    # optional: avoid check certificate name if true

# username & password may be None
mqttc.username_pw_set(mqtt_username, mqtt_password)

# Attempt to connect to broker. If this fails, issue CRITICAL

try:
    mqttc.connect(mqtt_host, mqtt_port, 60)
except Exception, e:
    status = 2
    message = "Connection to %s:%d failed: %s" % (mqtt_host, mqtt_port, str(e))
    exitus(status, message)

rc = 0
while userdata['have_response'] == False and rc == 0:
    rc = mqttc.loop()
    if time.time() - userdata['start_time'] > max_wait:
        message = 'timeout waiting for PUB'
        status = 2
        break

mqttc.disconnect()

exitus(status, message)