Getting token to access Azure keyvault fails with Operation Cancelled message - azure

Question

We're trying to access a secret from Azure keyvault.
The code tries to get an access token that will then be used to retrieve the secret from the keyvault.
private async Task<string> GetAccessToken(string authority, string resource, string scope)
{
...
return this.useGlobalMsiRunAs ?
await tokenProviderGlobal.Value.KeyVaultTokenCallback(authority, resource, scope) :
await tokenProvider.Value.KeyVaultTokenCallback(authority, resource, scope);
}
useGlobalMsiRunAs is set to false and the code calls tokenProvider.Value.KeyVaultTokenCallback(...).
The above call fails with Access token could not be acquired. The operation was canceled
---> Microsoft.Azure.Services.AppAuthentication.AzureServiceTokenProviderException: Parameters: Connection String: [No connection string specified], Resource: https://vault.azure.net, Authority: https://login.windows.net/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Exception Message: Tried the following 3 methods to get an access token, but none of them worked.
Parameters: Connection String: [No connection string specified], Resource: https://vault.azure.net, Authority: https://login.windows.net//xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Exception Message: Tried to get token using Managed Service Identity. Access token could not be acquired. The operation was canceled.
Parameters: Connection String: [No connection string specified], Resource: https://vault.azure.net, Authority: https://login.windows.net//xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Exception Message: Tried to get token using Visual Studio. Access token could not be acquired. Environment variable LOCALAPPDATA not set.
Parameters: Connection String: [No connection string specified], Resource: https://vault.azure.net, Authority: https://login.windows.net//xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Exception Message: Tried to get token using Azure CLI. Access token could not be acquired.
at Microsoft.Azure.Services.AppAuthentication.AzureServiceTokenProvider.GetAuthResultAsyncImpl(String resource, String authority, CancellationToken cancellationToken)
at Microsoft.Azure.Services.AppAuthentication.AzureServiceTokenProvider.<get_KeyVaultTokenCallback>b__12_0(String authority, String resource, String scope)
at abc.xyz.Common.Service.AzureKeyVaultAccess.GetAccessToken(String authority, String resource, String scope) in d:\dbs\el\manb\private\ClientCenter\MT\Source\Common\ClientCenter.Common.NetStandard\Service\AzureKeyVaultAccess.cs:line 472
at Microsoft.Azure.KeyVault.KeyVaultCredential.PostAuthenticate(HttpResponseMessage response)
at Microsoft.Azure.KeyVault.KeyVaultCredential.ProcessHttpRequestAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at Microsoft.Azure.KeyVault.KeyVaultClient.GetSecretWithHttpMessagesAsync(String vaultBaseUrl, String secretName, String secretVersion, Dictionary`2 customHeaders, CancellationToken cancellationToken)
at Microsoft.Azure.KeyVault.KeyVaultClientExtensions.GetSecretAsync(IKeyVaultClient operations, String vaultBaseUrl, String secretName, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
We are using a managed identity, so the answer in this question didn't help.
Can someone please give some leads as to what could be wrong here?

Answer 1

You can use either system-assigned or user-assigned managed identity for your AKS Cluster’s Agent pool
Once you assign the system-assigned or user-assigned managed identity for your AKS Cluster’s Agent pool, you can add the access policy in your key vault with read access to the secrets
Then you would be able to access Azure Key vault secrets from your AKS cluster
Your code can use a managed identity to request access tokens for services that support Azure AD authentication. Azure takes care of rolling the credentials that are used by the service instance
To access key vault using system-assigned managed identity, you can use DefaultAzureCredential() class
If you are using user-assigned managed identity, you can use ManagedIdentityCredential() class
Reference: c# - How to use user-assigned managed identity to access Key Vault for Function App Config in Azure - Stack Overflow