arduino-iot-cloud 1.4.0

Arduino IoT Cloud Python client

Arduino IoT Cloud Python client ☁️🐍☁️

This is a Python client for the Arduino IoT Cloud, which runs on both CPython and MicroPython. The client supports basic and advanced authentication methods, synchronous and asynchronous modes and provides a user-friendly API that allows users to connect to the cloud and create and link local objects to cloud objects with just a few lines of code.

Minimal Example

The following basic example shows how to connect to the Arduino IoT cloud using basic username and password authentication, and control an LED from a dashboard's switch widget.

from secrets import DEVICE_ID
from secrets import SECRET_KEY

# Switch callback, toggles the LED.
def on_switch_changed(client, value):
    # Note the client object passed to this function can be used to access
    # and modify any registered cloud object. The following line updates
    # the LED value.
    client["led"] = value

# 1. Create a client object, which is used to connect to the IoT cloud and link local
# objects to cloud objects. Note a username and password can be used for basic authentication
# on both CPython and MicroPython. For more advanced authentication methods, please see the examples.
client = ArduinoCloudClient(device_id=DEVICE_ID, username=DEVICE_ID, password=SECRET_KEY)

# 2. Register cloud objects.
# Note: The following objects must be created first in the dashboard and linked to the device.
# When the switch is toggled from the dashboard, the on_switch_changed function is called with
# the client object and new value args.
client.register("sw1", value=None, on_write=on_switch_changed)

# The LED object is updated in the switch's on_write callback.
client.register("led", value=None)

# 3. Start the Arduino cloud client.
client.start()

Your secrets.py file should look like this:

WIFI_SSID  = ""  # WiFi network SSID (for MicroPython)
WIFI_PASS  = ""  # WiFi network key  (for MicroPython)
DEVICE_ID  = "" # Provided by Arduino cloud when creating a device.
SECRET_KEY = "" # Provided by Arduino cloud when creating a device.

Note that by default, the client runs in asynchronous mode. In this mode, the client runs an asyncio loop that updates tasks and records, polls networking events, etc. The client also supports a synchronous mode, which requires periodic client polling. To run the client in synchronous mode, pass sync_mode=True when creating a client object and call client.update() periodically after connecting. For example:

# Run the client in synchronous mode.
client = ArduinoCloudClient(device_id=DEVICE_ID, ..., sync_mode=True)
....
client.register("led", value=None)
....
# In synchronous mode, this function returns immediately after connecting to the cloud.
client.start()

# Update the client periodically.
while True:
    client.update()
    time.sleep(0.100)

For more detailed examples and advanced API features, please see the examples.

Testing on CPython/Linux

The client supports basic authentication using a username and password, and the more advanced key/cert pair stored on filesystem or in a crypto device. To test this functionality, the following steps can be used to emulate a crypto device (if one is not available) using SoftHSM on Linux.

Create softhsm token

Using the first available slot, in this case 0

softhsm2-util --init-token --slot 0 --label "arduino" --pin 1234 --so-pin 1234

Import the key and certificate using p11tool

p11tool --provider=/usr/lib/softhsm/libsofthsm2.so --login --set-pin=1234 --write "pkcs11:token=arduino" --load-privkey key.pem --label "Mykey"
p11tool --provider=/usr/lib/softhsm/libsofthsm2.so --login --set-pin=1234 --write "pkcs11:token=arduino" --load-certificate cert.pem --label "Mykey"

List objects

This should print the key and certificate

p11tool --provider=/usr/lib/softhsm/libsofthsm2.so --login --set-pin=1234 --list-all pkcs11:token=arduino

Object 0:
	URL: pkcs11:model=SoftHSM%20v2;manufacturer=SoftHSM%20project;serial=841b431f98150134;token=arduino;id=%67%A2%AD%13%53%B1%CE%4F%0E%CB%74%34%B8%C6%1C%F3%33%EA%67%31;object=mykey;type=private
	Type: Private key (EC/ECDSA)
	Label: mykey
	Flags: CKA_WRAP/UNWRAP; CKA_PRIVATE; CKA_SENSITIVE;
	ID: 67:a2:ad:13:53:b1:ce:4f:0e:cb:74:34:b8:c6:1c:f3:33:ea:67:31

Object 1:
	URL: pkcs11:model=SoftHSM%20v2;manufacturer=SoftHSM%20project;serial=841b431f98150134;token=arduino;id=%67%A2%AD%13%53%B1%CE%4F%0E%CB%74%34%B8%C6%1C%F3%33%EA%67%31;object=Mykey;type=cert
	Type: X.509 Certificate (EC/ECDSA-SECP256R1)
	Expires: Sat May 31 12:00:00 2053
	Label: Mykey
	ID: 67:a2:ad:13:53:b1:ce:4f:0e:cb:74:34:b8:c6:1c:f3:33:ea:67:31

Deleting Token:

When done with the token it can be deleted with the following command:

softhsm2-util --delete-token --token "arduino"

Run the example script

• Set KEY_PATH, CERT_PATH and DEVICE_ID in examples/example.py.
• Provide a CA certificate in a ca-root.pem file or set CA_PATH to None if it's not used.
• Override the default pin and provide ENGINE_PATH and MODULE_PATH in ssl_params if needed.
• Run the example:

python examples/example.py

Testing on MicroPython

MicroPython supports both modes of authentication: basic mode, using a username and password, and mTLS with the key and certificate stored on the filesystem or a secure element (for provisioned boards). To use key and certificate files stored on the filesystem, they must first be converted to DER format. The following commands can be used to convert from PEM to DER:

openssl ec -in key.pem -out key.der -outform DER
openssl x509 -in cert.pem -out cert.der -outform DER

In this case KEY_PATH, CERT_PATH, can be set to the key and certificate DER paths, respectively:

KEY_PATH = "path/to/key.der"
CERT_PATH = "path/to/cert.der"

Alternatively, if the key and certificate are stored on the SE, their URIs can be specified in the following format:

KEY_PATH = "se05x:token=0x00000064"
CERT_PATH = "se05x:token=0x00000065"

With the key and certificate set, the example can be run with the following command examples/micropython_advanced.py

Useful links

• micropython-senml library
• micropython-cbor2 library
• m2crypto
• umqtt.simple
• openssl docs/man