Sending Messages from Leaf Device Downstream device not being handled by IoT Edge running at Transparent Gateway

Question

I have followed all the instruction for setting up a "Downstream Device" to send messages through IoT Edge running in Transparent Gateway. I believe my routing rules are correct, but my Function module is not receiving any of the Messages through the message flow.

These are the instruction I've followed: https://docs.microsoft.com/en-us/azure/iot-edge/how-to-create-transparent-gateway-linux

I am using 2 Linxu VMs (ubuntu 16.04.5).

1. IoT Edge Transparent Gateway VM is configured with all the certs properly setup, configured and verified. I've been able to using the openssl tool from the

openssl s_client -connect {my-gateway-machine-name-dns-name}.centralus.cloudapp.azure.com:8883 -CAfile /certs/certs/azure-iot-test-only.root.ca.cert.pem -showcerts

2. Downstream device running on Linux VM with Certs installed and verified. My connection string is as follows:

   HostName={IoTHubName}.azure-devices.net;DeviceId=TC51_EdgeDownStreamDevice01;SharedAccessKey={My-Shared-Access-Key}=GatewayHostName={my-gateway-machine-name-dns-name}.centralus.cloudapp.azure.com

a. I have verified I get a successful verification of the SSL cert using the openssl tool. b. I'm using the the following in my downstream device for my connection using the NodeJS SDK

var client = DeviceClient.fromConnectionString(connectionString, Mqtt); c. I can see the messages showing up at the Azure IoT Hub in the Cloud, but I can't get my module running on the IoT Edge Transparent Gateway to be hit.

3. Here are my routing rules configured for the edgeHub as specified in "Routing messages from downstream devices" in the sample doc page.

This is what the example docs show: { "routes":{ "sensorToAIInsightsInput1":"FROM /messages/* WHERE NOT IS_DEFINED($connectionModuleId) INTO BrokeredEndpoint(\"/modules/ai_insights/inputs/input1\")", "AIInsightsToIoTHub":"FROM /messages/modules/ai_insights/outputs/output1 INTO $upstream" } }

This is what my routing configuration is set to: "routes": { "downstreamBatterySensorToBatteryDataFunctionInput1": "FROM /* WHERE NOT IS_DEFINED($connectionModuleId) INTO BrokeredEndpoint(\"/modules/BatteryDataFunctionModule/inputs/input1\")", "BatteryDataFunctionModuleToIoTHub": "FROM /messages/modules/BatteryDataFunctionModule/outputs/* INTO $upstream" }

** Note that I've used by "FROM /* WHERE NOT IS_DEFINED" and "FROM /messages/* WHERE NOT IS_DEFINED"

4. My module on the IoT Edge is setup as a Function. When I use the out of the box example where the simulator device is another module running on the IoT Edge, then my function is hit correctly. Its only when I'm trying to use a "Downstream Device" that the module is not being triggered.

I have enabled "Debug Logging for the IoT Edge Service" running on my Transparent Gateway.

This is the basic Run method for the Function module:

#r "Microsoft.Azure.Devices.Client"
#r "Newtonsoft.Json"

using System.IO;
using Microsoft.Azure.Devices.Client;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

// Filter messages based on the temperature value in the body of the     message and the temperature threshold value.
public static async Task Run(Message messageReceived, IAsyncCollector<Message> output, TraceWriter log)
{

How can I figure out how to get my Module running in IoT Edge to be hit/triggered from a Downstream device?

Answer 1

So, you say you are seeing messages show up in IoT Hub, but not in Edge... A couple of things:

you posted this as your connection string in your node app: HostName={IoTHubName}.azure-devices.net;DeviceId=TC51_EdgeDownStreamDevice01;SharedAccessKey={My-Shared-Access-Key}=GatewayHostName={my-gateway-machine-name-dns-name}.centralus.cloudapp.azure.com

Did you copy/paste this exactly? the reason I ask is that, between the shared access key and the word "GatewayHostName", you have an equals sign and not a semi-colon..

it should be: HostName={IoTHubName}.azure-devices.net;DeviceId=TC51_EdgeDownStreamDevice01;SharedAccessKey={My-Shared-Access-Key};GatewayHostName={my-gateway-machine-name-dns-name}.centralus.cloudapp.azure.com

(note the ';' before GatewayHostName… if you really did have an equals sign there instead of a semicolon, there's no telling what kind of chaos that would cause :-)

Secondly, in your route, you call your module BatteryDataFunctionModule.. just want to make sure that module name is exact, including being case-sensitive. You probably know that, but don't want to assume..

Finally, if the two things above check out, can you add an addition debugging route that sends the 'incoming data' to IoTHub as well..
"FROM /* WHERE NOT IS_DEFINED($connectionModuleId) INTO $upstream"

so we can make sure the messages are actually making it through iot edge.

Answer 2

There are 2 problems that needed to be addressed to get the Downstream Device to communication

1. Thanks to @Steve-Busby-Msft I needed to have a semi-colon (;) at the end of the SharedAccessKey and before the GatewayHostName

you posted this as your connection string in your node app: HostName={IoTHubName}.azure-devices.net;DeviceId=TC51_EdgeDownStreamDevice01;SharedAccessKey={My-Shared-Access-Key}=GatewayHostName={my-gateway-machine-name-dns-name}.centralus.cloudapp.azure.com

2. The NodeJS application Downstream Device also has to load up the cert correctly at the 'Application level'.

Notice the section of code for

var edge_ca_cert_path = '[Path to Edge CA certificate]';

Node JS Downstream Application

'use strict';

var fs = require('fs');
var Protocol = require('azure-iot-device-mqtt').Mqtt;
// Uncomment one of these transports and then change it in fromConnectionString to test other transports
// var Protocol = require('azure-iot-device-http').Http;
// var Protocol = require('azure-iot-device-amqp').Amqp;
var Client = require('azure-iot-device').Client;
var Message = require('azure-iot-device').Message;

// 1) Obtain the connection string for your downstream device and to it
//    append this string GatewayHostName=<edge device hostname>;
// 2) The edge device hostname is the hostname set in the config.yaml of the Edge device
//    to which this sample will connect to.
//
// The resulting string should look like the following
//  "HostName=<iothub_host_name>;DeviceId=<device_id>;SharedAccessKey=<device_key>;GatewayHostName=<edge device hostname>"
var connectionString = '[Downstream device IoT Edge connection string]';

// Path to the Edge "owner" root CA certificate
var edge_ca_cert_path = '[Path to Edge CA certificate]';

// fromConnectionString must specify a transport constructor, coming from any transport package.
var client = Client.fromConnectionString(connectionString, Protocol);

var connectCallback = function (err) {
  if (err) {
    console.error('Could not connect: ' + err.message);
  } else {
    console.log('Client connected');
    client.on('message', function (msg) {
      console.log('Id: ' + msg.messageId + ' Body: ' + msg.data);
      // When using MQTT the following line is a no-op.
      client.complete(msg, printResultFor('completed'));
      // The AMQP and HTTP transports also have the notion of completing, rejecting or abandoning the message.
      // When completing a message, the service that sent the C2D message is notified that the message has been processed.
      // When rejecting a message, the service that sent the C2D message is notified that the message won't be processed by the device. the method to use is client.reject(msg, callback).
      // When abandoning the message, IoT Hub will immediately try to resend it. The method to use is client.abandon(msg, callback).
      // MQTT is simpler: it accepts the message by default, and doesn't support rejecting or abandoning a message.
    });

    // Create a message and send it to the IoT Hub every second
    var sendInterval = setInterval(function () {
      var windSpeed = 10 + (Math.random() * 4); // range: [10, 14]
      var temperature = 20 + (Math.random() * 10); // range: [20, 30]
      var humidity = 60 + (Math.random() * 20); // range: [60, 80]
      var data = JSON.stringify({ deviceId: 'myFirstDownstreamDevice', windSpeed: windSpeed, temperature: temperature, humidity: humidity });
      var message = new Message(data);
      message.properties.add('temperatureAlert', (temperature > 28) ? 'true' : 'false');
      console.log('Sending message: ' + message.getData());
      client.sendEvent(message, printResultFor('send'));
    }, 2000);

    client.on('error', function (err) {
      console.error(err.message);
    });

    client.on('disconnect', function () {
      clearInterval(sendInterval);
      client.removeAllListeners();
      client.open(connectCallback);
    });
  }
};

// Provide the Azure IoT device client via setOptions with the X509
// Edge root CA certificate that was used to setup the Edge runtime
var options = {
  ca : fs.readFileSync(edge_ca_cert_path, 'utf-8'),
};

client.setOptions(options, function(err) {
  if (err) {
    console.log('SetOptions Error: ' + err);
  } else {
    client.open(connectCallback);
  }
});