IoT with MQTT and Kubernetes

This repository contains:

• An example IoT thing: the fridge.
• A Kubernetes operator to instantiate cloud controllers for things.

Run go get at the root of the repo.

We will need one MQTT hub with its ca.pem and two devices with their crt.pem and key.pem.

Fridge

Go to the fridge/ folder and run go run main.go --help.

Usage:
  fridge CLIENT_ID [TOPIC=/fr/fridge/51966]

Flags:
  -c, --client-crt string   Path to client certificate (default "crt.pem")
  -k, --client-key string   Path to client key (default "key.pem")
      --help                Print help
  -s, --server-crt string   Path to server certificate (default "ca.pem")
  -u, --url string          Server URL to connect to (default "tls://iot.fr-par.scw.cloud:8883")

1. Add a device to your hub and put its certificate and key into crt.pem and key.pem.
2. Put the hub certificate into ca.pem.
3. Run go run main.go <YOUR_CLIENT_ID>.

State

The fridge should now be up and running and broadcasting its state to the MQTT hub every second.

2020/09/14 11:48:03 {"T":25,"D":4,"O":false}
2020/09/14 11:48:04 {"T":24,"D":4,"O":false}
2020/09/14 11:48:05 {"T":23,"D":4,"O":false}

Abbreviation	Name	Description
T	Temperature	The inner temperature of the fridge
D	Desired temperature	The desired temperature inside our fridge
O	Open	Is the door open

Commands

The fridge can be operated through your keyboard:

Key	Action
O	Open the door
C	Close the door
Arrow Up	Increase the desired temperature by 1
Arrow Down	Decrease the desired temperature by 1
I	Print fridge state
A	Emulate an alert by sending a message on ${topic}/alert

Kubernetes Operator

You must have a Kubernetes cluster to install the operator. The easiest way to run a Kubernetes cluster locally in a docker container is k3d.

Go to the operator/ folder and run make install to install custom resource definitions managed by the operator to your cluster.

Available resources

Kind	API Version	Description
Fridge	iot.ctison.dev/v1	Monitor a fridge thing through MQTT hub

Fridge spec

Field	Description
topic	Topic to listen for and where to publish alerts (${topic}/alerts)

Example configuration

Let's create the following resource in our cluster by running kubectl apply -f config/samples/iot_v1_fridge.yaml.

apiVersion: iot.ctison.dev/v1
kind: Fridge
metadata:
  name: fridge-sample
spec:
  topic: /fr/fridge/51966

Run the operator

The operator has the following usage:

Usage: fridge-operator CLIENT_ID

Available flags:
  -client-cert string
        Path to client certificate (default "crt.pem")
  -client-key string
        Path to client key (default "key.pem")
  -enable-leader-election
        Enable leader election for controller manager. Enabling this will ensure there is only one active controller manager.
  -kubeconfig string
        Paths to a kubeconfig. Only required if out-of-cluster.
  -master --kubeconfig
        (Deprecated: switch to --kubeconfig) The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster.
  -metrics-addr string
        The address the metric endpoint binds to. (default ":8080")
  -server-cert string
        Path to server certificate (default "ca.pem")
  -url string
        URL of the mqtt server. (default "tls://iot.fr-par.scw.cloud:8883")

1. Add a device to your hub and put its certificate and key into crt.pem and key.pem.
2. Put the hub certificate into ca.pem.
3. Run go run main.go <YOUR_CLIENT_ID>.

The operator should now spawn a controller for our Fridge resource and this controller should start dumping received messages from the hub in the configured topic. Every time the controller detects the door of the fridge is open, it should send an alert to ${topic}/alert asking to close the door!