IoT gateway tutorial

Create a registry, create a gateway, bind a device, listen for messages, and publish messages.

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For detailed documentation that includes this code sample, see the following:

• Gateways

Code sample

Python

For more information, see the Cloud IoT Core Python API reference documentation.

To authenticate to Cloud IoT Core, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

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import csv
import datetime
import logging
import os
import sys
import time

sys.path.append(os.path.join(os.path.dirname(__file__), "..", "manager"))  # noqa
import cloudiot_mqtt_example  # noqa
import manager  # noqa


logging.getLogger("googleapiclient.discovery_cache").setLevel(logging.CRITICAL)

cloud_region = "us-central1"
device_id_template = "test-device-{}"
gateway_id_template = "test-gateway-{}"
topic_id = f"test-device-events-topic-{int(time.time())}"

ca_cert_path = "resources/roots.pem"
log_path = "config_log.csv"
rsa_cert_path = "resources/rsa_cert.pem"
rsa_private_path = "resources/rsa_private.pem"

if (
    "GOOGLE_CLOUD_PROJECT" not in os.environ
    or "GOOGLE_APPLICATION_CREDENTIALS" not in os.environ
):
    print("You must set GCLOUD_PROJECT and GOOGLE_APPLICATION_CREDENTIALS")
    quit()

project_id = os.environ["GOOGLE_CLOUD_PROJECT"]
service_account_json = os.environ["GOOGLE_APPLICATION_CREDENTIALS"]

pubsub_topic = f"projects/{project_id}/topics/{topic_id}"
registry_id = f"test-registry-{int(time.time())}"

base_url = f"https://console.cloud.google.com/iot/locations/{cloud_region}"
edit_template = "{}/registries/{}?project={}".format(base_url, "{}", "{}")

device_url_template = "{}/registries/{}/devices/{}?project={}".format(
    base_url, "{}", "{}", "{}"
)

mqtt_bridge_hostname = "mqtt.googleapis.com"
mqtt_bridge_port = 8883

num_messages = 15
jwt_exp_time = 20
listen_time = 30


if __name__ == "__main__":
    print("Running demo")

    gateway_id = device_id_template.format("RS256")
    device_id = device_id_template.format("noauthbind")

    print(f"Creating registry: {registry_id}")
    manager.create_registry(
        service_account_json, project_id, cloud_region, pubsub_topic, registry_id
    )

    print(f"Creating gateway: {gateway_id}")
    manager.create_gateway(
        service_account_json,
        project_id,
        cloud_region,
        registry_id,
        None,
        gateway_id,
        rsa_cert_path,
        "RS256",
    )

    print(f"Creating device to bind: {device_id}")
    manager.create_device(
        service_account_json, project_id, cloud_region, registry_id, device_id
    )

    print("Binding device")
    manager.bind_device_to_gateway(
        service_account_json,
        project_id,
        cloud_region,
        registry_id,
        device_id,
        gateway_id,
    )

    print(f"Listening for messages for {listen_time} seconds")
    print("Try setting configuration in: ")
    print(f"\t{edit_template.format(registry_id, project_id)}")
    try:
        input("Press enter to continue")
    except SyntaxError:
        pass

    def log_callback(client):
        def log_on_message(unused_client, unused_userdata, message):
            if not os.path.exists(log_path):
                with open(log_path, "w") as csvfile:
                    logwriter = csv.writer(csvfile, dialect="excel")
                    logwriter.writerow(["time", "topic", "data"])

            with open(log_path, "a") as csvfile:
                logwriter = csv.writer(csvfile, dialect="excel")
                logwriter.writerow(
                    [
                        datetime.datetime.now(tz=datetime.timezone.utc).isoformat(),
                        message.topic,
                        message.payload,
                    ]
                )

        client.on_message = log_on_message

    cloudiot_mqtt_example.listen_for_messages(
        service_account_json,
        project_id,
        cloud_region,
        registry_id,
        device_id,
        gateway_id,
        num_messages,
        rsa_private_path,
        "RS256",
        ca_cert_path,
        mqtt_bridge_hostname,
        mqtt_bridge_port,
        jwt_exp_time,
        listen_time,
        log_callback,
    )

    print("Publishing messages demo")
    print(f"Publishing: {num_messages} messages")
    cloudiot_mqtt_example.send_data_from_bound_device(
        service_account_json,
        project_id,
        cloud_region,
        registry_id,
        device_id,
        gateway_id,
        num_messages,
        rsa_private_path,
        "RS256",
        ca_cert_path,
        mqtt_bridge_hostname,
        mqtt_bridge_port,
        jwt_exp_time,
        "Hello from gateway_demo.py",
    )

    print("You can read the state messages for your device at this URL:")
    print(f"\t{device_url_template}".format(registry_id, device_id, project_id))
    try:
        input("Press enter to continue after reading the messages.")
    except SyntaxError:
        pass

    # Clean up
    manager.unbind_device_from_gateway(
        service_account_json,
        project_id,
        cloud_region,
        registry_id,
        device_id,
        gateway_id,
    )
    manager.delete_device(
        service_account_json, project_id, cloud_region, registry_id, device_id
    )
    manager.delete_device(
        service_account_json, project_id, cloud_region, registry_id, gateway_id
    )
    manager.delete_registry(service_account_json, project_id, cloud_region, registry_id)

What's next

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