Examples: Lambda Functions on AWS IoT Greengrass

Publish Data from the MQTT-Broker to the Amazon Cloud

This lambda function subscribes data from MQTT-Broker from Edge Device and publishes is to the Amazon Cloud to the topic tv/greengrass.

#!/usr/bin/python
import paho.mqtt.subscribe as subscribe
import paho.mqtt.publish as publish
import traceback
import json

def function_handler(event, context):
    return

# AWS part
# Change following parameters
aws_host = "a10kx625z9icrs-ats.iot.eu-central-1.amazonaws.com"  # Endpoint
aws_port = 8883
aws_tls = {'certfile': "/home/pi/Downloads/certs/1b9a6e0dcb.cert.pem",
           'keyfile': "/home/pi/Downloads/certs/1b9a6e0dcb.private.key",
           'ca_certs': "/home/pi/Downloads/certs/root.ca.pem"
           }

# TV part
#Change following parameters
tv_iot_api_version = "v1.0"
tv_host = "localhost"
tv_port = 18884

tv_tls = {'certfile': "/home/pi/Downloads/test_client_greengrass/cert-7a2b7efc1ad1473d87e049517a19628b.pem",
          'keyfile': "/home/pi/Downloads/test_client_greengrass/key-7a2b7efc1ad1473d87e049517a19628b.pem",
          'ca_certs': "/home/pi/Downloads/test_client_greengrass/TeamViewerAuthority.crt"}

client_id = "fd9e67783b7441ffb7cd62dda121567a"
sensor_id = "111804"

def subscribe_data():
    try:
        mqtt_topic_subscribe_data = "/" + tv_iot_api_version + "/" + client_id + "/sensor/" + sensor_id + "/livedata"
        print("Suscribing to " + mqtt_topic_subscribe_data)
        subscribe.callback(on_subscribe, mqtt_topic_subscribe_data, hostname=tv_host, port=tv_port, tls=tv_tls)
    except Exception as e:
        traceback.print_exc()
        print(str(e))

def on_subscribe(client, userdata, message):
    json_message = json.loads(message.payload.decode('utf8'))
    msgArr = []
    for metric in json_message["metrics"]:
        messageJ = {}
        messageJ['metricId'] = metric["metricId"]
        messageJ['metricValue'] = metric["value"]
        msgArr.append(messageJ)

    msgs = []
    msgs.append({'topic': "tv/greengrass", 'payload': json.dumps(msgArr)})
    print(msgs)
    publish.multiple(msgs, hostname=aws_host, port=aws_port, tls=aws_tls)
subscribe_data()

Fetch Data from the Amazon Cloud

This lambda function subscribes the data from Amazon Cloud and pushes the data to TeamViewer metrics and real-time data can be visualized with the IoT Management Console and the dashboard.

#!/usr/bin/python
import paho.mqtt.subscribe as subscribe
import paho.mqtt.publish as publish
import traceback
import json
import ssl
def function_handler(event, context):
    return

# AWS part
# Change following parameters
aws_host = "a10kx625z9icrs-ats.iot.eu-central-1.amazonaws.com"  # Endpoint
aws_port = 8883
aws_tls = {'certfile': "/home/pi/Downloads/certs/1b9a6e0dcb.cert.pem",
           'keyfile': "/home/pi/Downloads/certs/1b9a6e0dcb.private.key",
           'ca_certs': "/home/pi/Downloads/certs/root.ca.pem",
           'tls_version': ssl.PROTOCOL_TLSv1_2
          }

# TV part
#Change following parameters
tv_iot_api_version = "v1.0"
tv_host = "localhost"
tv_port = 18884

tv_tls = {'certfile': "/home/pi/Downloads/test_client_greengrass/cert-7a2b7efc1ad1473d87e049517a19628b.pem",
          'keyfile': "/home/pi/Downloads/test_client_greengrass/key-7a2b7efc1ad1473d87e049517a19628b.pem",
          'ca_certs': "/home/pi/Downloads/test_client_greengrass/TeamViewerAuthority.crt"}

client_id = "7a2b7efc1ad1473d87e049517a19628b"
sensor_id = "71b91c40fb2d4f61bec2fa593172085d"

def aws_subscribe():
    print("Suscribing to tv/greengrassSub")
    subscribe.callback(on_subscribe, "tv/greengrassSub", hostname=aws_host, port=aws_port, tls=aws_tls)

def on_subscribe(client, userdata, message):
    try:
        metric_data = json.loads(message.payload.decode('utf8'))
        mqtt_topic_push_data = "/" + tv_iot_api_version + "/" + client_id + "/sensor/" + sensor_id + "/metric/pushValues"
        # metric_data =  {"metrics": [{"value": 1, "metricId": "7ad8ad3e2dbe4cdcba0ee3ec0cbd2717"}]}
        msgs = []
        msgs.append({'topic': mqtt_topic_push_data, 'payload': json.dumps(metric_data)})
        print(msgs)
        publish.multiple(msgs, hostname=tv_host, port=tv_port, tls=tv_tls)

    except Exception as e:
        traceback.print_exc()
        print(str(e))
aws_subscribe()