Tring to connect to Azure Digital Twins from Visual Studio Code: DefaultAzureCredential(); .getToken error

Question

I'm trying to connect to an Azure Digital wins Instance from Visual Studio Code, using Javascript API for Azure Digital Twins.

I have npm install @azure/identity installed, and npm install @azure/digital-twins-core,

I can login to Azure portal using "az login" from the Powershell terminal in VS Code. It finds my account and subscription and logs in.

az account get-access-token --output json returns my token.

Here's the code I'm trying to run. It basicall should create two models in the Azure Digital Twins instance:

'''

const { DefaultAzureCredential } = require("@azure/identity");
const { DigitalTwinsClient } = require("@azure/digital-twins-core");
const { v4 } = require("uuid");
const { inspect } = require("util");


async function main() {
  const modelId = `dtmi:model_${v4()
    .split("-")
    .join("")};1`;
  const componentId = `dtmi:component_${v4()
    .split("-")
    .join("")};1`;
  const digitalTwinId = `digitalTwin-${v4()}`;

  const temporaryComponent = {
    "@id": componentId,
    "@type": "Interface",
    "@context": "dtmi:dtdl:context;2",
    displayName: "Component1",
    contents: [
      {
        "@type": "Property",
        name: "ComponentProp1",
        schema: "string"
      }
    ]
  };

  const temporaryModel = {
    "@id": modelId,
    "@type": "Interface",
    "@context": "dtmi:dtdl:context;2",
    displayName: "TempModel",
    contents: [
      {
        "@type": "Property",
        name: "Prop1",
        schema: "double"
      },
      {
        "@type": "Component",
        name: "Component1",
        schema: componentId
      }
    ]
  };

  const temporaryTwin = {
    $dtId: digitalTwinId,
    $metadata: {
      $model: modelId
    },
    Prop1: 42,
    Component1: {
      $metadata: {},
      ComponentProp1: "value1"
    }
  };

  // AZURE_DIGITALTWINS_URL: The URL to your Azure Digital Twins instance
  const url = 'https://ParADIM-ADT-Dev.api.wcus.digitaltwins.azure.net';
  if (url === undefined) {
    throw new Error("Required environment variable AZURE_DIGITALTWINS_URL is not set.");
  }

  // DefaultAzureCredential is provided by @azure/identity. It supports
  // different authentication mechanisms and determines the appropriate
  // credential type based of the environment it is executing in. See
  // https://www.npmjs.com/package/@azure/identity for more information on
  // authenticating with DefaultAzureCredential or other implementations of
  // TokenCredential.
  const credential = new DefaultAzureCredential();
  const serviceClient = new DigitalTwinsClient(url, credential);

  // Create models
  const newModels = [temporaryComponent, temporaryModel];
  const models = await serviceClient.createModels(newModels);
  //console.log(`Created Models:`);
  //console.log(inspect(models));
  
}

main().catch((err) => {
  console.log("error code: ", err.code);
  console.log("error message: ", err.message);
  console.log("error stack: ", err.stack);
});

'''

Here's the error I'm getting: C:\\Program Files\\nodejs\\node.exe .\\index.js error code: undefined error message: Unexpected end of JSON input error stack: Error: Unexpected end of JSON input at AzureCliCredential.getToken (c:\\ADTProject\\node_modules@azure\\identity\\dist\\index.js:1529:27) at processTicksAndRejections (internal/process/task_queues.js:95:5) at async DefaultAzureCredential.getToken (c:\\ADTProject\\node_modules@azure\\identity\\dist\\index.js:1358:25)

So, an unexpected end of JSON input. Thi error is coming from @azure\\identity\\dist\\index.js which is part of the azure\\identity package, so not code I wrote. The code I'm using is from a tutorial, and the JSON is compliant. Seems it's getting an error executing the getToken function.

ANy help appreciated! I've hit a wall on this one!

THANKS!!

Answer 1

As the code pulled from the documentation, looking into the error trace it got failed to retrieve a token from specified credentials, might be issue in how we are passing it. Below is how we usually connect in JavaScript:

const client = new SecretClient(keyVaultUrl, new DefaultAzureCredential());

Below is the sample code to communicate with Cosmos and storage:

import { SecretClient } from '@azure/keyvault-secrets';
import { DefaultAzureCredential } from '@azure/identity';
import { CosmosClient } from '@azure/cosmos';

const keyVaultUrl = process.env('APP_KEY_VAULT_URI');
const credential = new DefaultAzureCredential();
let storageClient;
let cosmosClient;

async function configureClients() {
    const kvClient = new SecretClient(keyVaultUrl, credential);
    const storageUri = await client.getSecret('storageUri');
    const cosmosDbConnectionString = await client.getSecret('cosmosDb');

    cosmosClient = new CosmosClient(cosmosDbConnectonString);
    storageClient = new BlobServiceClient(storageUri, credential);
}

For more information about environmental variables, setting keyvault refer to azure sdk blog to know about Authentication