Learn MQTT with Go

Learning MQTT with Golang by doing. This repo is a simple example of using a Golang application as a client (pub & sub) of an MQTT broker.

1883, Eclipse Mosquitto unsecured (opening the port on the internet is not recommended).

Architecture

Ideally I would like this application to resemble the above design. Conceptually, there

Development

For local development we use Mosquitto as our MQTT broker, with TLS enabled.

sudo apt install mosquitto-clients

First generate local development certs using:

make gen-local-tls-certs

This will create CA, server, and client certificates suitable for local development. Server and CA certs are created in ./.mosquitto/certs. The client cert is create in the project root.

Start the local development environment with:

make start-dev

Stop the local development environment with:

make stop-dev

Testing

Unit tests can be run with:

make test

Integration tests are run via:

make test-integration

Usage

To run the application end to end first start the development server:

make start-dev

Next we can start our subscriber. The following command connects to the TLS listener port.

go run cmd/subscriber/main.go --host 0.0.0.0 --port 8883

Design Considerations

See DESIGN_CONCIDERATIONS.md

Resources:

• Mosquitto Docs
• Mosquitto TLS Tutorial
• Golang MQTT Tutorial
• MQTT as a Service
• Using Wireshark for MQTT Analysis
• Caddy as reverse proxy
• Using Python paho MQTT client with TLS
• ESP32 Micropython MQTT with TLS: Note cert file format for uPy MQTT client needs to be in .der format which is a binary format.
• TLS refresher
• HA Mosquitto in K8s
• Lamport Timestamps Tutorial
• Vector Clocks Lecture