Intro
I am trying to have an alexa communicate with a dragonboard to turn on an LED. I am using aws' iot core javascript sdk to listen for mqtt calls and python-shell to execute a python script to blink the LED. I modified device-example.js to look as follows
device-example.js
/*
* Copyright 2010-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
//node.js deps
//npm deps
//app deps
const deviceModule = require('..').device;
const cmdLineProcess = require('./lib/cmdline');
var PythonShell = require('python-shell')
//begin module
function processTest(args) {
//
// The device module exports an MQTT instance, which will attempt
// to connect to the AWS IoT endpoint configured in the arguments.
// Once connected, it will emit events which our application can
// handle.
//
const device = deviceModule({
keyPath: args.privateKey,
certPath: args.clientCert,
caPath: args.caCert,
clientId: args.clientId,
region: args.region,
baseReconnectTimeMs: args.baseReconnectTimeMs,
keepalive: args.keepAlive,
protocol: args.Protocol,
port: args.Port,
host: args.Host,
debug: args.Debug
});
var timeout;
var count = 0;
const minimumDelay = 250;
if (args.testMode === 1) {
device.subscribe('topic_1');
} else {
device.subscribe('topic_2');
}
if ((Math.max(args.delay, minimumDelay)) !== args.delay) {
console.log('substituting ' + minimumDelay + 'ms delay for ' + args.delay + 'ms...');
}
timeout = setInterval(function() {
count++;
if (args.testMode === 1) {
device.publish('topic_2', JSON.stringify({
mode1Process: count
}));
} else {
device.publish('topic_1', JSON.stringify({
mode2Process: count
}));
}
}, Math.max(args.delay, minimumDelay)); // clip to minimum
//
// Do a simple publish/subscribe demo based on the test-mode passed
// in the command line arguments. If test-mode is 1, subscribe to
// 'topic_1' and publish to 'topic_2'; otherwise vice versa. Publish
// a message every four seconds.
//
device
.on('connect', function() {
console.log('connect');
});
device
.on('close', function() {
console.log('close');
});
device
.on('reconnect', function() {
console.log('reconnect');
});
device
.on('offline', function() {
console.log('offline');
});
device
.on('error', function(error) {
console.log('error', error);
});
device
.on('message', function(topic, payload) {
console.log('message', topic, payload.toString());
if(payload.toString() === 'on') {
PythonShell.run('blink_led.py', { uid:0 }, function(err, result) {
if(err) throw err;
console.log('finished');
});
}
});
}
module.exports = cmdLineProcess;
if (require.main === module) {
cmdLineProcess('connect to the AWS IoT service and publish/subscribe to topics using MQTT, test modes 1-2',
process.argv.slice(2), processTest);
}
I wrote a simple script to execute the javascript
start.sh
# stop script on error
set -e
# run pub/sub sample app using certificates downloaded in package
printf "\nRunning pub/sub sample application...\n"
node node_modules/aws-iot-device-sdk/examples/device-example.js --host-name=a1v3w5qj5oveq1.iot.us-east-1.amazonaws.com --private-key=/home/linaro/software/aws-iot/rube.private.key --client-certificate=/home/linaro/software/aws-iot/rube.cert.pem --ca-certificate=/home/linaro/software/aws-iot/root-CA.crt
Question
When I execute the script, every component functions, the script receives mqtt calls, then turns on the LED. When I try to turn the script into a basic systemd service, the python is not executed. The systemd script is below
iot.service
[Unit]
Description=AWS IOT Listener
After=network.target
[Service]
Type=simple
User=linaro
ExecStart=/usr/bin/env sudo /home/linaro/software/aws-iot/start.sh
[Install]
WantedBy=multi-user.target
As a service, MQTT calls are received, but the python is not called at all. No error is thrown. How can I have the python be called when the script is called as a systemd service?
Additional Information: System: Debian jessie
Result of running ./start.sh (not service)
Running pub/sub sample application...
connect
message topic_1 on
finished
"finished" comes from the python script
Result of running as a service
● iot.service - AWS IOT Listener
Loaded: loaded (/lib/systemd/system/iot.service; disabled; vendor preset: enabled)
Active: active (running) since Mon 2018-05-28 06:08:42 UTC; 19s ago
Main PID: 2190 (sudo)
CGroup: /system.slice/iot.service
├─2190 sudo /home/linaro/software/aws-iot/start.sh
├─2191 sh /home/linaro/software/aws-iot/start.sh
└─2192 node node_modules/aws-iot-device-sdk/examples/device-exampl...
May 28 06:08:42 linaro-alip sudo[2190]: linaro : TTY=unknown ; PWD=/ ; USE...h
May 28 06:08:42 linaro-alip sudo[2190]: pam_unix(sudo:session): session open...)
May 28 06:08:42 linaro-alip env[2190]: Running pub/sub sample application...
May 28 06:08:44 linaro-alip env[2190]: connect
May 28 06:09:00 linaro-alip env[2190]: message topic_1 on
Hint: Some lines were ellipsized, use -l to show in full.
Not sure what exactly fixed the problem but here is what I did to make it work