Resolving Azure Global Endpoint 404 Error in Quarkus REST Client

Understanding the Azure Device Registration Failure

When integrating with Azure’s Device Provisioning Service (DPS) through a Quarkus REST client, unexpected errors such as a 404 Not Found can create significant challenges. This error might arise even if the client setup and endpoint URL seem correct at first glance.

The 404 error typically indicates that the requested resource does not exist on the server. This can be particularly puzzling when you're confident the parameters and paths match those in the official Azure documentation. Such an error could stem from various subtle issues in the request structure.

In this context, properly understanding the REST API structure, including query parameters, authorization headers, and payload formatting, is crucial. The documentation you are referencing may be outdated, or there could be a mismatch in the API version being used.

By analyzing the Quarkus client configuration and the API endpoint closely, we can pinpoint the exact cause of this error. This guide will help you ensure a successful device registration by focusing on common pitfalls and providing actionable insights to resolve this issue.

Exploring the Solution to Azure REST Client Errors

The Quarkus REST client interface presented in the example is designed to interact with the Azure Device Provisioning Service (DPS). The primary goal is to register a device by invoking the relevant Azure endpoint. The structure of this interface leverages Quarkus’s integration with the MicroProfile Rest Client API. The @RegisterRestClient annotation is crucial as it defines the REST client and links it to the configuration key in the application.properties file. This configuration ensures that the base URL for the DPS is correctly referenced. The @Path annotation specifies the endpoint path that will be appended to the base URL when making requests.

When calling the registerDevice method, the parameters passed include a payload containing the device information, the registration ID, and the authorization token. The @PathParam annotation is used to insert the registration ID into the request URL dynamically. This flexibility is vital in REST clients because the registration ID varies depending on the device being registered. Similarly, the @HeaderParam annotation inserts the SAS token into the Authorization header, ensuring that the request is authenticated properly according to Azure’s security requirements.

The second script improves upon the initial implementation by introducing enhanced error handling and logging. This is done by wrapping the registerDevice method in a try-catch block. The ClientWebApplicationException is caught when a REST API call fails, such as when a 404 error is encountered. Logging the error through Quarkus’s logging library allows for better diagnostics when troubleshooting issues. This is a common best practice in software development, as it helps developers pinpoint the source of errors without having to debug the code line by line.

In the third script, the focus shifts to unit testing. Using Mockito, a powerful framework for Java unit testing, we mock the AzureRestClient to simulate its behavior without making actual HTTP calls. This makes the tests faster and more reliable. Methods like mock() and when() allow developers to define the expected behavior of the mocked client, ensuring that the test can check if the client behaves as expected. The mock response simulates a successful device registration, allowing us to validate the output. These unit tests help ensure that the code is robust and works correctly under different conditions, without interacting with external systems.

import jakarta.ws.rs.*;
import jakarta.ws.rs.core.MediaType;
import jakarta.ws.rs.core.Response;
import org.eclipse.microprofile.rest.client.inject.RegisterRestClient;
import org.eclipse.microprofile.rest.client.annotation.ClientHeaderParam;
import org.jboss.resteasy.reactive.ClientWebApplicationException;
@RegisterRestClient(configKey = "dps-api")
@Path("/registrations")
public interface AzureRestClient {
    @PUT
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    @Path("/{registrationId}/register?api-version=2021-10-01")
    Response registerDevice(RegistrationPayload payload,
                          @PathParam("registrationId") String registrationId,
                          @HeaderParam("Authorization") String authorization);
}

import jakarta.ws.rs.*;
import jakarta.ws.rs.core.MediaType;
import jakarta.ws.rs.core.Response;
import org.eclipse.microprofile.rest.client.inject.RegisterRestClient;
import org.jboss.logging.Logger;
@RegisterRestClient(configKey = "dps-api")
@Path("/registrations")
public interface AzureRestClient {
    Logger logger = Logger.getLogger(AzureRestClient.class);
    @PUT
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    @Path("/{registrationId}/register?api-version=2021-10-01")
    default Response registerDevice(RegistrationPayload payload,
                          @PathParam("registrationId") String registrationId,
                          @HeaderParam("Authorization") String authorization) {
        try {
            return this.registerDevice(payload, registrationId, authorization);
        } catch (ClientWebApplicationException e) {
            logger.error("Error registering device: " + e.getMessage());
            throw e;
        }
    }
}

import static org.mockito.Mockito.*;
import org.junit.jupiter.api.Test;
import jakarta.ws.rs.core.Response;
public class AzureRestClientTest {
    private AzureRestClient client = mock(AzureRestClient.class);
    @Test
    public void testRegisterDeviceSuccess() {
        RegistrationPayload payload = new RegistrationPayload("device123", "groupId");
        Response mockResponse = Response.ok().build();
        when(client.registerDevice(payload, "device123", "validSasToken"))
            .thenReturn(mockResponse);
        Response response = client.registerDevice(payload, "device123", "validSasToken");
        assertEquals(200, response.getStatus());
    }
}

Resolving 404 Errors in Azure Device Registration with Quarkus

One of the key aspects when dealing with Azure's Device Provisioning Service (DPS) and encountering a 404 error is verifying the endpoint structure. The REST API provided by Azure is highly specific, and a common reason for receiving a 404 Not Found response could be related to an incorrect idScope. The idScope is critical because it identifies the provisioning service instance to which you are registering the device. Ensure that this is correctly set in the URL.

Another crucial factor is the SAS token used for authentication. A 404 response may occur if the SAS token is invalid or incorrectly formatted. Ensure that the token has been generated correctly using the right shared access key and that it's included in the Authorization header of the HTTP request. Additionally, check that the expiry time of the token is set appropriately. If the token expires before the request is made, it can lead to authentication errors.

Moreover, it's essential to ensure that the correct API version is being used in the request URL. The Azure DPS REST API evolves, and using an outdated or incorrect version may result in a 404 error. In the case of device registration, make sure the API version in the request URL matches the latest one specified in the Azure documentation. Staying updated with the documentation helps avoid such errors and improves overall integration success.