Unable to retrieve cosmosDB data using azure JavaScript function and Key Vault secret

Question

I am using Azure functions (JavaScript/node) to query and retrieve data from CosmosDB. That works fine. However, I haven't been successful at implementing key vault secrets to store the primary key for cosmosDB. I get the error:

Executed 'Functions.getProjects' (Failed, Id=f319f320-af1c-4283-a8f4-43cc6becb3ca, 
Duration=1289ms)
[6/7/2021 4:37:44 AM] System.Private.CoreLib: Exception while executing function: 
Functions.getProjects. System.Private.CoreLib: Result: Failure
Exception: Error: Required Header authorization is missing. Ensure a valid Authorization token 
is passed.

I have followed multiple tutorials on what I need to do to run the code in Azure as well as what I need to do to run the code locally in VS code. To run in Azure, I created my key vault and added the secret. I enabled system assigned managed identity on my function so that it creates a service principal. I then created an access policy in key vault that allows my function/service principal GET, LIST capabilities. I get the same error when testing the function in Azure as I do when I test locally.

My code: config.js - endpoint and key obscured for security

const config = {
  endpoint: "https://<mysiteonazure>.documents.azure.com:443/",
  key: 
  "myreallylongkeyhiddenforsecurity",
  databaseId: "projectsDB",
  containerId: "projects",
  partitionKey: { kind: "Hash", paths: ["/category"] },
};
module.exports = config;

My code: index.js

const config = require("../sharedCode/config");
const { CosmosClient } = require("@azure/cosmos");

const { DefaultAzureCredential } = require("@azure/identity");
const { SecretClient } = require("@azure/keyvault-secrets");

// this value is specified in local.settings.json file for local testing
const keyVaultName = process.env["KEY_VAULT_NAME"];

const keyVaultUri = `https://${keyVaultName}.vault.azure.net`;

// checks to see if local.settings.json has value first, indicates local
// second uses managed identity, indicating azure, since local.settings.js not uploaded
const credential = new DefaultAzureCredential();

const secretClient = new SecretClient(keyVaultUri, credential);

module.exports = async function (context, req) {
  
  const endpoint = config.endpoint;
  const key = await secretClient.getSecret("cosmosProjectKey");
  const keyx = key.value;

  const client = new CosmosClient({ endpoint, keyx });

  const database = client.database(config.databaseId);
  const container = database.container(config.containerId);

  const querySpec = {
    query: "SELECT * from c",
  };

  let myprojects = [];

  const { resources: items } = await container.items
    .query(querySpec)
    .fetchAll();

  items.forEach((item) => {
    myprojects.push(`${item.id} - ${item.project}`);
  });

  context.res = {
    // status: 200, /* Defaults to 200 */
    body: items,
  };
};

As I mentioned, my code works when I hard-code the key in the config file (not the best JS coding). I've removed all the comments that show that the value of the key is returned from key vault. I also left out that I created another service principal, that I believe is used when I try to access the key vault when running the function locally.

Any help greatly appreciated.

Answer 1

Please change the following lines of code:

const key = await secretClient.getSecret("cosmosProjectKey");
const keyx = key.value;

to

const secretKey = await secretClient.getSecret("cosmosProjectKey");
const key = secretKey.value;

And create your CosmosClient using the following

const client = new CosmosClient({ endpoint, key });

Other option would be to create your CosmosClient like this:

const client = new CosmosClient({ endpoint, key: keyx });