Drogue Cloud

Drogue Cloud is our IoT connectivity layer. It will offer the IoT specific endpoints, authenticate devices, and normalize events.

We will need to perform the following steps:

Create a new application
Register a new device
Finally, send some data

Costs

We will be using the public Drogue IoT sandbox, which is completely free for trying out Drogue IoT.

Create application

Log in to the public sandbox console, and navigate to the "Applications" view. Create a new application with a unique name and remember that name.

Figure 1. New application dialog

Once it is created, we need to configure the event source, sending data to our Knative endpoint. For this we need the following information from the previous steps:

Public endpoint URL
Endpoint token

Go to the "YAML" tab of the application, and edit the .spec section (create one if there is none):

spec:
  knative:
    endpoint:
      url: https://pusher.your-public-url.codeengine.appdomain.cloud (1)
      auth:
        bearer:
          token: abcdef123456 (2)

1	Public URL of Knative endpoint
2	Token configured in the Knative endpoint

After storing the configuration, the changes will be applied. After a bit, the state should change back to "Ready" and in the YAML section, you should see the condition KnativeReady in the section .status.conditions to become True. Currently, you need to reload the data to see the change.

Register device

Now we need to register a new device. While we don’t use any physical device, the procedure is the same for simulating one using e.g. curl, http or mqtt.

Navigate to the "Devices" view, and select your application from the drop-down in the top. Use the New device button to create a new device named device1:

Figure 2. Dialog to create a new device

The newly created device does not have any credentials assigned, so it currently cannot be used to connect. For the sake of simplicity, we will just add a plain text password to the device. Navigate to the "YAML" tab of the device and add the following:

spec:
  credentials:
    credentials: (1)
      - pass: my-password (2)

1	Indeed, the `credentials` field contains another field named `credentials`.
2	The password, stored plain text

Plain text passwords

Storing passwords plain text might not be a good idea. Don’t worry, Drogue Cloud can make use of hashed passwords or X.509 client certificates.

Using the command line tool drg, you can make use of them pretty easily. But for this tutorial, we wanted to stick to the web browser.

Send some data

We are good to go for a first test. We wired up Drogue Cloud with TimescaleDB using Knative, registered a device, and created a table in the database. So, let’s send some data (be sure to replace the application and password):

curl -v -XPOST -u device1@my-application:my-password https://http.sandbox.drogue.cloud/v1/state -d '{"features": {"temperature":{"value":42}}}'

If you prefer MQTT, you can do the same using mqtt:

mqtt pub -v -h mqtt.sandbox.drogue.cloud -p 443 -u 'device1@my-application' -pw 'my-password' -s -t telemetry -m '{"features": {"temperature":{"value":42}}}'

When the command has completed successfully, check the table with psql:

tsdb=> select * from temperatures;
             time              | device_id | temperature
-------------------------------+-----------+-------------
 2022-03-11 16:41:44.799424+00 | device1   |          42
(1 row)

tsdb=>

Yay!

What’s next?

So, we wired it all up and data ends up in the Timescale database.

Now comes the fun part, as we want to make use of that data and leverage the powers of TimescaleDB, and draw some nice charts.