Demonstrates replacing the Managed Identity authentication strategy to do custom authentication such as Azure CLI login as a fall-back.

AzureCredentialSqlAuthenticationProvider.cs

using Azure.Core;
using Azure.Identity;
using Microsoft.Data.SqlClient;
using System.Threading.Tasks;

namespace Example
{
    public class AzureCredentialSqlAuthenticationProvider : SqlAuthenticationProvider
    {
        public async override Task<SqlAuthenticationToken> AcquireTokenAsync(SqlAuthenticationParameters parameters)
        {
            var azureTokenCredential = new ChainedTokenCredential(
                new ManagedIdentityCredential(parameters.UserId == string.Empty ? null : parameters.UserId),
                new AzureCliCredential(),
                new VisualStudioCodeCredential(),
                new VisualStudioCredential());

            var tokenResponse = await azureTokenCredential.GetTokenAsync(new TokenRequestContext(new[] { parameters.Resource }), cancellationToken: default);

            return new SqlAuthenticationToken(tokenResponse.Token, tokenResponse.ExpiresOn);
        }

        public override bool IsSupported(SqlAuthenticationMethod authenticationMethod)
        {
            return authenticationMethod == SqlAuthenticationMethod.ActiveDirectoryManagedIdentity
                || authenticationMethod == SqlAuthenticationMethod.ActiveDirectoryMSI;
        }
    }
}

Program.cs

using Microsoft.Data.SqlClient;

namespace Example
{
    /*
     * Enable developer credential fall-back to support local developing
     * 
     * https://github.com/dotnet/SqlClient/issues/815
     * https://docs.microsoft.com/en-us/sql/connect/ado-net/introduction-microsoft-data-sqlclient-namespace?view=sql-server-ver15#azure-active-directory-managed-identity-authentication
     * 
     * To use this authentication, just add this to your connection string instead of credentials
     * Authentication=Active Directory Managed Identity; User Id={ObjectIdOfManagedIdentity};
     * 
     * Requires Microsoft.Data.SqlClient >= 2.1.1
     */
     
    var azureSqlTokenProvider = new AzureCredentialSqlAuthenticationProvider();
      
    SqlAuthenticationProvider.SetProvider(SqlAuthenticationMethod.ActiveDirectoryManagedIdentity, azureSqlTokenProvider);
    SqlAuthenticationProvider.SetProvider(SqlAuthenticationMethod.ActiveDirectoryMSI, azureSqlTokenProvider);
}