Authentication basics

Hong Ooi

There are a number of ways to authenticate to the Azure Resource Manager API with AzureRMR. This vignette goes through the most common scenarios.

Interactive authentication

This is the scenario where you’re using R interactively, such as in your local desktop or laptop, or in a hosted RStudio Server, Jupyter notebook or ssh session. The first time you authenticate with AzureRMR, you run create_azure_login():

# on first use
library(AzureRMR)
az <- create_azure_login()

Notice that you don’t enter your username and password.

AzureRMR will attempt to detect which authentication flow to use, based on your session details. In most cases, it will bring up the Azure Active Directory (AAD) login page in your browser, which is where you enter your user credentials. This is also known as the “authorization code” flow.

There are some complications to be aware of:

All of the above arguments can be combined, eg this will authenticate using the device code flow, with an explicit tenant name, and a custom app ID:

az <- create_azure_login(tenant="yourtenant", app="yourappid", auth_type="device_code")

If needed, you can also supply other arguments that will be passed to AzureAuth::get_azure_token().

Having created the login, in subsequent sessions you run get_azure_login(). This will load your previous authentication details, saving you from having to login again. If you specified the tenant in the create_azure_login() call, you’ll also need to specify it for get_azure_login(); the other arguments don’t have to be repeated.

az <- get_azure_login()

# if you specified the tenant in create_azure_login
az <- get_azure_login(tenant="yourtenant")

Non-interactive authentication

This is the scenario where you want to use AzureRMR as part of an automated script or unattended session, for example in a deployment pipeline. The appropriate authentication flow in this case is the client credentials flow.

For this scenario, you must have a custom app ID and client secret. On the client side, these are supplied in the app and password arguments. You must also specify your tenant as AAD won’t be able to detect it from a user’s credentials.

az <- create_azure_login(tenant="yourtenant", app="yourccappid", password="client_secret")

In the non-interactive scenario, you don’t use get_azure_login(); instead, you simply call create_azure_login() as part of your script.

Creating a custom app registration

This part is meant mostly for Azure tenant administrators, or users who have the appropriate rights to create AAD app registrations.

You can create your own app registration to authenticate with, if the default Azure CLI app ID is insufficient. In particular, you’ll need a custom app ID if you are using AzureRMR in a non-interactive session. If security is a concern, a custom app ID also lets you restrict the scope of the resources that AzureRMR that manipulate.

You can create a new app registration using any of the usual methods. For example to create an app registration in the Azure Portal (https://portal.azure.com/), click on “Azure Active Directory” in the menu bar down the left, go to “App registrations” and click on “New registration”. Name the app something suitable, eg “AzureRMR custom app”.

Once the app registration has been created, note the app ID and, if applicable, the client secret. The latter can’t be viewed after app creation, so make sure you note its value now.

It’s also possible to authenticate with a client certificate (public key), but this is more complex and we won’t go into it here. For more details, see the Azure Active Directory documentation and the AzureAuth intro vignette.

Set the app role and scope

You’ll also need to set the role assignment and scope(s) for your app ID. The former determines the kinds of actions that AzureRMR can take; the latter determines which resources those action can be applied to.

The main role assignments are

It’s generally recommended to use the most restrictive role assignment that still lets you carry out your tasks.

In the Portal, you can set the role assignment for your app ID by going to a specific subscription/resource group/resource and clicking on “Access Control (IAM)”. Role assignments for subscriptions and resource groups will propagate to objects further down in the hierarchy. Any resources that don’t have a role for your app will not be accessible.