Amazon AWS recently released the IOT service, a utility for lightweight devices to create and consume messages on the internet, and also in the case of AWS to leverage the rest of their feature set, such as Kinesis, Lambda, S3, DynamoDB, etc.
Of course, I didn’t fancy using the AWS SDK to do this. I just wanted to get mosquitto_pub and mosquitto_sub working on the command line, so see how easy it would be to get plain old MQTT working with it. It’s not that difficult.
First off, create a working directory, and download the root CA file for your client to use
wget https://www.symantec.com/content/en/us/enterprise/verisign/roots/VeriSign-Class%203-Public-Primary-Certification-Authority-G5.pem -O rootCA.pem
Now that you have the root certificate, head to the AWS IOT console, sign up or sign in, and click on the “Create a Resource”, and then the “Create a thing” button. Give it a name, and optional attributes, and hit “Create”. Once the page loads, you can now select your new “Thing” and aim for the “Connect a Device” button. You can then choose which SDK to use. That’s up to you, but after you select it and hit the “Generate Certificate and Policy” button you will be invited to download three files – public and private keys, and a cert. Do so, save them in your working directory, and also somewhere safe if you plan on deleting the directory later. You can’t download them again.
Now you have to ascertain what your broker endpoint is. The AWS IOT UI isn’t the clearest on this, but it’s helpfully hidden inside the parameter “REST API Endpoint”. You’ll need to select a thing from the console, and it appears at the top right. It’s just the domain part of the REST endpoint, so “https://A2HAT5HHRF2IFT.iot.eu-west-1.amazonaws.com/things/KyleG_Test/shadow” becomes A2HAT5HHRF2IFT.iot.eu-west-1.amazonaws.com
Once you have that information, and have the certificate files in place, it’s a simple case of passing some SSL options to the mosquitto client tools.
mosquitto_pub –cafile rootCA.pem –cert dec39df945-certificate.pem.crt –key dec39df945-private.pem.key -h A2HAT5HHRF2IFT.iot.eu-west-1.amazonaws.com -p 8883 -q 1 -d -t ‘$aws/things/KyleG_Desktop/shadow/update’ -m ‘testing’