Azure - Is it possible to setup environment variables with Enterprise Applications?

In our project, we do not use App Registrations, instead we use Enterprise applications in Azure.

I am trying to access a secret from Azure Key Vault in local development(.NET Core), which requires DefaultAzureCredential which in turn uses environment variables namely AZURE_CLIENT_ID, AZURE_CLIENT_SECRET/AZURE_CLIENT_CERTIFICATE_PATH, and AZURE_TENANT_ID. AZURE_CLIENT_SECRET is present in App Registration only.

Is it possible to setup environment variables with Enterprise Applications?

If not, is there any way to access the secret in Azure Key Vault using .NET Core?

Anyway, when we want to access Azure KeyVault secret, we have to grant access policy. And we can grant access policy for Azure AD applications, specific User/Group, and ManagedIdentity instance generally.

When we want to use DefauleAzureCredential, we have the option to set client id/client secret/tenant id for an Azure AD app, since you don't have the client secret, maybe this is not available for you. Then we can also use user credential, I think it's good for us to use this when we test the code in local machine, only we need to do is adding access policy for a user, then sign in Visual Studio with that user, then we can simply get authorized to access the vault secret by code below:

public async Task<string> IndexAsync()
        {
            const string secretName = "clientsecret";
            var kvUri = "https://keyvaultname.vault.azure.net/";
            var a = new DefaultAzureCredential();
            var client = new SecretClient(new Uri(kvUri), a);
            var secret = await client.GetSecretAsync(secretName);
            string secretVaule = secret.Value.Value;
            return secretVaule ;
        }

We can also use ManagedIdentity, but this requires the app to be host in Azure. Just following this official document. It also contains a sample inside the document.

builder.Configuration.AddAzureKeyVault(
       new Uri("https://vaultName.vault.azure.net/"),
       new DefaultAzureCredential(
           new DefaultAzureCredentialOptions { ManagedIdentityClientId = "userManagedIdentityClientId" }//required when using user ManagedIdentity
       ));