The Device Twin service holds information about the state of the connected devices. Once a device is registered in the IoT Identity Service, a device twin it created to hold the current and desired state of the device.

The device twin record holds:

• Summary of the device
• Last known heartbeat from the device
• The groups that the device belongs to
• Details about the device's state
• Details about the device's desired state

The service provides a cache so the devices can be monitored by the IoT Management Service, and relays actions to the device IoT agent e.g. to install a new application.

The project uses vendorized dependencies using govendor. Development has been done on minimum Go version 1.12.1.

$ go get github.com/canonical/iot-devicetwin
$ cd iot-devicetwin
$ go build ./...

go run cmd/devicetwin/main.go -help
 -configdir string
       Directory path to the config file (default "certs")
 -datasource string
       The data repository data source
 -driver string
       The data repository driver (default "memory")
 -mqttport string
       Port of the MQTT broker (default "8883")
 -mqtturl string
       URL of the MQTT broker (default "mqtt.example.com")
 -port string
       The port the service listens on (default "8040")

The service connects to the MQTT Broker using the certificates in the configdir (named ca.crt, server.crt and server.key).

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