Servizio AMQP (ex MQTT)

bin-ubuntu/get-config

@@ -224,8 +224,8 @@ start() {
             # reset and remove exam configuration files
             echo "$NORMAL_CONFIG_NAME" > /local/config_name
             echo "" > /local/examid
-            rm /local/esame-machine.conf >/dev/null 2>&1
-            rm /local/esame-machine.conf.prev >/dev/null 2>&1
+            #rm /local/esame-machine.conf >/dev/null 2>&1
+            #rm /local/esame-machine.conf.prev >/dev/null 2>&1
             rm /local/iptables >/dev/null 2>&1
             rm /local/iptables.prev >/dev/null 2>&1
             rm /local/mk-homedir >/dev/null 2>&1
@@ -250,6 +250,14 @@ start() {
         ESAME_USB_GUARD=${RES_USB_GUARD}
     fi
 
+
+    # extract ESAME_AMQP from configuration file
+    ESAME_AMQP=0
+    RES_AMQP=`awk -F= -v key="ESAME_AMQP" '$1==key {print $2}' /local/esame-machine.conf | sed "s/\"//g"`
+    if [[ "${RES_AMQP}" != "" ]]; then
+        ESAME_AMQP=${RES_AMQP}
+    fi
+
     if [[ -n "${CONFIG_NAME}" ]]; then
         echo "Configuration: ${CONFIG_NAME}"
         if [ "${EXAM_ID}" != "" ]; then
@@ -287,8 +295,8 @@ start() {
         # if [[ "$CONFIG_NAME" == "$NORMAL_CONFIG_NAME" ]]; then
         if [[ "${EXAM_ID}" == "" ]]; then
             # remove some files used by exam mode
-            rm /local/esame-machine.conf >/dev/null 2>&1
-            rm /local/esame-machine.conf.prev >/dev/null 2>&1
+            #rm /local/esame-machine.conf >/dev/null 2>&1
+            #rm /local/esame-machine.conf.prev >/dev/null 2>&1
             rm /local/iptables >/dev/null 2>&1
             rm /local/iptables.prev >/dev/null 2>&1
             rm /local/mk-homedir >/dev/null 2>&1
@@ -319,6 +327,16 @@ start() {
             fi
         fi
 
+        # if we use AMQP server, just disable esame-get-config.timer
+        if [[ ${ESAME_AMQP} == 1 ]]; then
+            systemctl disable esame-get-config.timer
+            systemctl stop esame-get-config.timer
+        # otherwise, enable it
+        else
+            systemctl enable esame-get-config.timer
+            systemctl start esame-get-config.timer
+        fi
+
         # choose the correct target
         # we have just booted/rebooted, update the current configuration via web service
         updateCurrentConfigId

bin-ubuntu/mqtt-subscribe

-#!/bin/bash
-#/usr/local/bin/lm-subscriber -b penelope.di.unipmn.it -t "lab98/config" -c "echo reboot..." -f /local/config_name \
-/usr/local/bin/lm-subscriber -b penelope.di.unipmn.it -t "lab98/config" -c "/usr/libexec/labmanager/get-config start" -f /local/config_name \
-	--port 8883 \
-	--auth-user sub_client \
-	--auth-pwd zse45rdx \
-	--ca-cert /etc/ssl/certs/mqtt_ca.crt \
-	-l DEBUG
-

bin-ubuntu/rabbitmq-client.py

@@ -3,76 +3,142 @@ import pika
 import dbus
 from random import randint
 from time import sleep
+import os
+import socket
+import logging
+
+#####################################################################
+# Conguration class
+#####################################################################
+class Config:
+    server_host = 'rabbitmq.edu-al.unipmn.it';
+    server_port = 5672;
+    server_user = 'labmanager-client';
+    server_password = '3aB7=2zV9:1jN3-4hE2';
+    server_virtualhost = 'labmanager';
+    server_exchange_name = 'labmanager-test';
+    server_exchange_type = 'x-recent-history'; # It's a plugin. Enable with 'rabbitmq-plugins enable rabbitmq_recent_history_exchange'
+    server_credentials = pika.PlainCredentials(server_user, server_password, True)
+    systemd_getconfig_unit_name = 'esame-get-config.service'
+    systemd_manager = None
+#####################################################################
+
+
+#####################################################################
+# LOGGER Configuration
+#####################################################################
+# Values: DEBUG, INFO, WARNING, ERROR, CRITICAL
+LOG_LEVEL = logging.INFO
+LOG_FORMAT = ('%(levelname) -10s %(asctime)s: %(message)s')
+
+LOGGER = logging.getLogger(__name__)
+#####################################################################
+
+
+#####################################################################
+'''
+Creates an object to interact with Systemd via DBUS
+'''
+#####################################################################
+def create_systemd_manager():
+    bus = dbus.SystemBus()
+    # Get systemd reference
+    systemd = bus.get_object(
+        'org.freedesktop.systemd1',
+        '/org/freedesktop/systemd1')
+    # Create systemd manager
+    systemd_manager = dbus.Interface(
+        systemd,
+        'org.freedesktop.systemd1.Manager')
+    return systemd_manager
+
+
+def random_sleep(min, max):
+    sleep_secs = randint(min, max)
+    LOGGER.info('Sleep %d seconds' % sleep_secs)
+    sleep(sleep_secs)
+
+
+'''
+On message callback
+'''
+def on_message_callback(ch, method, properties, body):
+    LOGGER.info('Received message \'%s\'' % body.decode('UTF-8'))
+
+    # Sleep a random number of seconds (between 1 and 10)
+    # to avoid all machines reboot at the same time
+    random_sleep(1, 10)
+    LOGGER.info('Starting Systemd service \'%s\'' %
+        Config.systemd_getconfig_unit_name)
+    start_unit = Config.systemd_manager.StartUnit(Config.systemd_getconfig_unit_name, 'fail')
+
+
+'''
+Main flow
+'''
+def main():
+    logging.basicConfig(level=LOG_LEVEL, format=LOG_FORMAT)
+
+    # If we don't use AMQP, just exit (if the variable is not set, set it to 0)
+    ESAME_AMQP = os.environ.get('ESAME_AMQP', '0')
+    LOGGER.info('ESAME_AMQP=%s', ESAME_AMQP)
+
+    if ESAME_AMQP != '1':
+        exit(0)
+
+    Config.systemd_manager = create_systemd_manager()
+
+    if Config.systemd_manager == None:
+        exit(0)
+
+    # Main loop
+    while True:
+        try:
+            connection = pika.BlockingConnection(
+                pika.ConnectionParameters(
+                    host=Config.server_host,
+                    port=Config.server_port,
+                    virtual_host=Config.server_virtualhost,
+                    credentials=Config.server_credentials
+                )
+            )
 
-server_host = 'rabbitmq.edu-al.unipmn.it';
-server_port = 5672;
-server_username = 'labmanager-client';
-server_pwd = '3aB7=2zV9:1jN3-4hE2';
-server_vhost = 'labmanager';
-
-exchange_name = 'labmanager-test';
-exchange_type = 'x-recent-history'; # It's a plugin. Enable with 'rabbitmq-plugins enable rabbitmq_recent_history_exchange'
-
-systemd_getconfig_unit_name = 'esame-get-config.service'
-
-bus = dbus.SystemBus()
-systemd = bus.get_object(
-    'org.freedesktop.systemd1',
-    '/org/freedesktop/systemd1'
-)
-
-manager = dbus.Interface(
-    systemd,
-    'org.freedesktop.systemd1.Manager'
-)
+            LOGGER.info('Connected to %s on port %d' % (Config.server_host, Config.server_port))
 
-server_credentials = pika.PlainCredentials(server_username, server_pwd, True)
+            channel = connection.channel()
 
-while True:
-    try:
+            '''
+            The publisher declares the exchange
+            Here we just check it exists before binding a queue to it
+            '''
+            check_exchange = channel.exchange_declare(exchange=Config.server_exchange_name, exchange_type=Config.server_exchange_type, passive=True)
+            LOGGER.info("check_exchange.method = %s", check_exchange.method)
 
-        connection = pika.BlockingConnection(
-            pika.ConnectionParameters(
-                host=server_host,
-                port=server_port,
-                virtual_host=server_vhost,
-                credentials=server_credentials
-            )
-        )
+            if type(check_exchange.method) is pika.spec.Exchange.DeclareOk:
 
-        channel = connection.channel()
+                result = channel.queue_declare(queue='', exclusive=True)
+                queue_name = result.method.queue
 
-        '''
-        L'exchange lo dichiara il publisher
-        TODO: qui serve sapere se esiste gia' e in caso negativo aspettare e ripetere (valutare se usare passive=true)
-        '''
-        # channel.exchange_declare(exchange=exchange_name, exchange_type=exchange_type)
+                channel.queue_bind(exchange=Config.server_exchange_name, queue=queue_name)
 
-        result = channel.queue_declare(queue='', exclusive=True)
-        queue_name = result.method.queue
+                LOGGER.info('Waiting for RabbitMQ messages')
 
-        channel.queue_bind(exchange=exchange_name, queue=queue_name)
+                channel.basic_consume(
+                    queue=queue_name, on_message_callback=on_message_callback, auto_ack=True)
 
-        print('Waiting for RabbitMQ messages')
+                channel.start_consuming()
 
-        def callback(ch, method, properties, body):
-            # Sleep a random number of seconds (between 1 and 10)
-            # to avoid all machines reboot at the same time
-            sleep(randint(1,10))
-            
-            print("RabbitMQ message: %s" % body.decode('UTF-8'))
-            start_unit = manager.StartUnit(systemd_getconfig_unit_name, 'fail')
+        # Intercept some error conditions and continue
+        except (pika.exceptions.ConnectionClosedByBroker,
+                pika.exceptions.AMQPChannelError,
+                pika.exceptions.AMQPConnectionError,
+                socket.gaierror,
+                ValueError) as error:
+            LOGGER.error('Error: %s', error.args)
 
-        channel.basic_consume(
-            queue=queue_name, on_message_callback=callback, auto_ack=True)
+            random_sleep(10, 20)
+            continue
 
-        channel.start_consuming()
 
-    except pika.exceptions.ConnectionClosedByBroker:
-        break
-    # Don't recover on channel errors
-    except pika.exceptions.AMQPChannelError:
-        break
-    # Recover on all other connection errors
-    except pika.exceptions.AMQPConnectionError:
-        continue
+if __name__ == '__main__':
+    main()

install-labmanager-ubuntu.sh

@@ -248,9 +248,11 @@ echo
 echo -e "\e[1mEnable systemd services...\e[0m"
 systemctl enable esame-*.service
 systemctl enable esamesync-esame.service
-# comment following 2 lines to use MQTT configuration change listener
-systemctl enable esame-get-config.timer
-systemctl start esame-get-config.timer
+# The following 2 commands are not needed anymore as get-config at boot time
+# will switch and activate the timer on and off when needed
+# (according to AMQP configuration)
+#systemctl enable esame-get-config.timer
+#systemctl start esame-get-config.timer
 echo
 echo
 

systemd-ubuntu/esame-get-config.service

@@ -5,4 +5,5 @@ Wants=network-online.target
 
 [Service]
 Type=oneshot
+EnvironmentFile=-/local/esame-machine.conf
 ExecStart=/usr/libexec/labmanager/get-config start

systemd-ubuntu/esame-mqtt.service

-[Unit]
-Description=Subscriber to LabManager MQTT server
-After=network-online.target esamesync-esame.service
-Wants=network-online.target esamesync-esame.service
-
-[Service]
-Type=oneshot
-RemainAfterExit=yes
-EnvironmentFile=-/local/esame-machine.conf
-ExecStart=/usr/libexec/labmanager/subscribe
-#ExecStop=
-
-[Install]
-WantedBy=esame.target graphical.target esamekiosk.target esameshow.target

systemd-ubuntu/esame-rabbitmq-client.service

@@ -5,7 +5,9 @@ Wants=network-online.target
 
 [Service]
 Type=oneshot
-ExecStart=/usr/bin/python3 /usr/libexec/labmanager/rabbitmq/rabbitmq-client.py
+RemainAfterExit=yes
+EnvironmentFile=-/local/esame-machine.conf
+ExecStart=/usr/bin/python3 /usr/libexec/labmanager/rabbitmq-client.py
 
 [Install]
-WantedBy=esame.target esamekiosk.target esameshow.target graphical.target
\ No newline at end of file
+WantedBy=esame.target esamekiosk.target esameshow.target graphical.target