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NOTE: This module will go out of support by March 31, 2023. For authenticating with Azure AD, use module azidentity instead. For help migrating from auth to azidentiy please consult the migration guide. General information about the retirement of this and other legacy modules can be found here.

Authentication

Typical SDK operations must be authenticated and authorized. The autorest.Authorizer interface allows use of any auth style in requests, such as inserting an OAuth2 Authorization header and bearer token received from Azure AD.

The SDK itself provides a simple way to get an authorizer which first checks for OAuth client credentials in environment variables and then falls back to Azure's Managed Service Identity when available, e.g. when on an Azure VM. The following snippet from the previous section demonstrates this helper.

import "github.com/Azure/go-autorest/autorest/azure/auth"

// create a VirtualNetworks client
vnetClient := network.NewVirtualNetworksClient("<subscriptionID>")

// create an authorizer from env vars or Azure Managed Service Idenity
authorizer, err := auth.NewAuthorizerFromEnvironment()
if err != nil {
    handle(err)
}

vnetClient.Authorizer = authorizer

// call the VirtualNetworks CreateOrUpdate API
vnetClient.CreateOrUpdate(context.Background(),
// ...

The following environment variables help determine authentication configuration:

  • AZURE_ENVIRONMENT: Specifies the Azure Environment to use. If not set, it defaults to AzurePublicCloud. Not applicable to authentication with Managed Service Identity (MSI).
  • AZURE_AD_RESOURCE: Specifies the AAD resource ID to use. If not set, it defaults to ResourceManagerEndpoint for operations with Azure Resource Manager. You can also choose an alternate resource programmatically with auth.NewAuthorizerFromEnvironmentWithResource(resource string).

More Authentication Details

The previous is the first and most recommended of several authentication options offered by the SDK because it allows seamless use of both service principals and Azure Managed Service Identity. Other options are listed below.

Note: If you need to create a new service principal, run az ad sp create-for-rbac -n "<app_name>" in the azure-cli. See these docs for more info. Copy the new principal's ID, secret, and tenant ID for use in your app, or consider the --sdk-auth parameter for serialized output.

  • The auth.NewAuthorizerFromEnvironment() described above creates an authorizer from the first available of the following configuration:

    1. **Client Credentials**: Azure AD Application ID and Secret.

    - `AZURE_TENANT_ID`: Specifies the Tenant to which to authenticate.
    - `AZURE_CLIENT_ID`: Specifies the app client ID to use.
    - `AZURE_CLIENT_SECRET`: Specifies the app secret to use.

2. **Client Certificate**: Azure AD Application ID and X.509 Certificate.

    - `AZURE_TENANT_ID`: Specifies the Tenant to which to authenticate.
    - `AZURE_CLIENT_ID`: Specifies the app client ID to use.
    - `AZURE_CERTIFICATE_PATH`: Specifies the certificate Path to use.
    - `AZURE_CERTIFICATE_PASSWORD`: Specifies the certificate password to use.

3. **Resource Owner Password**: Azure AD User and Password. This grant type is *not
   recommended*, use device login instead if you need interactive login.

    - `AZURE_TENANT_ID`: Specifies the Tenant to which to authenticate.
    - `AZURE_CLIENT_ID`: Specifies the app client ID to use.
    - `AZURE_USERNAME`: Specifies the username to use.
    - `AZURE_PASSWORD`: Specifies the password to use.

4. **Azure Managed Service Identity**: Delegate credential management to the
   platform. Requires that code is running in Azure, e.g. on a VM. All
   configuration is handled by Azure. See [Azure Managed Service
   Identity](https://docs.microsoft.com/azure/active-directory/msi-overview)
   for more details.

  • The auth.NewAuthorizerFromFile() method creates an authorizer using credentials from an auth file created by the Azure CLI. Follow these steps to utilize:

    1. Create a service principal and output an auth file using az ad sp create-for-rbac --sdk-auth > client_credentials.json.
    2. Set environment variable AZURE_AUTH_LOCATION to the path of the saved output file.
    3. Use the authorizer returned by auth.NewAuthorizerFromFile() in your client as described above.

  • The auth.NewAuthorizerFromCLI() method creates an authorizer which uses Azure CLI to obtain its credentials.

    The default audience being requested is https://management.azure.com (Azure ARM API). To specify your own audience, export AZURE_AD_RESOURCE as an evironment variable. This is read by auth.NewAuthorizerFromCLI() and passed to Azure CLI to acquire the access token.

    For example, to request an access token for Azure Key Vault, export

    AZURE_AD_RESOURCE="https://vault.azure.net"

  • auth.NewAuthorizerFromCLIWithResource(AUDIENCE_URL_OR_APPLICATION_ID) - this method is self contained and does not require exporting environment variables. For example, to request an access token for Azure Key Vault:

    auth.NewAuthorizerFromCLIWithResource("https://vault.azure.net")

    To use NewAuthorizerFromCLI() or NewAuthorizerFromCLIWithResource(), follow these steps:

    1. Install Azure CLI v2.0.12 or later. Upgrade earlier versions.
    2. Use az login to sign in to Azure.

    If you receive an error, use az account get-access-token to verify access.

    If Azure CLI is not installed to the default directory, you may receive an error reporting that az cannot be found.
    Use the AzureCLIPath environment variable to define the Azure CLI installation folder.

    If you are signed in to Azure CLI using multiple accounts or your account has access to multiple subscriptions, you need to specify the specific subscription to be used. To do so, use:

    az account set --subscription <subscription-id>

    To verify the current account settings, use:

    az account list

  • Finally, you can use OAuth's Device Flow by calling auth.NewDeviceFlowConfig() and extracting the Authorizer as follows:

    config := auth.NewDeviceFlowConfig(clientID, tenantID)
a, err := config.Authorizer()