Configure Azure AD authentication for a web app (App Services)

In this post I will describe the basic steps that needs to be done to configure App Service Authentication using Azure Active Directory.

Out of the box, App Services allows us to put in front of our system an authentication and authorization layer. For basic flows, us described below, the configuration can be done directly from Azure Portal, without having to write a line of code.


Step 1: Enable App Service Authentication
This step can be done directly from Azure Portal, from “Authentication / Authorization” tab.
After this, once you specify that you want to use “Azure Active Directory Provider”, do not forget to select “Log in with Azure Active Directory” from "Action to take when request is not authenticated". This is required if you want to not allow anonymous users to access your web app. By selecting this option, you will redirect unauthenticated users to the login page.
Don’t forget to hit “Save” (smile).

Step 2: Create and configure Azure AD Application
This step is done from the portal also, when you click on “Azure Active Directory” on the previous tab. You can use express configuration and let Azure to create a new Azure AD App inside the AD. The Azure AD App is the bridge between the Azure AD and your application, specifying what you can access from AD.
Keep in mind that you need to go grand access permissions inside “Manage Permission” tab. If you want to play a little with them, select all permissions from AD and click on the grant permissions.

Step 3: Specify users that can access your web app
In this moment even if you have the web app secure using Azure AD, but you didn’t specified yet the list of users that are allowed to access your web app. When you are using the free tire of AD, you need to specify users by name, you cannot use roles and groups.
For this, you need to browse from Azure Portal to “Azure Active Directory” and go to “Enterprise Applications”. Just select your “Azure AD App” from “All Applications” and navigate to “Users and Groups”.

We are done! Have fun!

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