Using Managed Service Identity with Key Vault from a .NET Azure Function

So Managed Service Identity along with Azure Functions support went GA recently. If you want to read the announcement and also want to get an overview of MSI, head over here: https://blogs.msdn.microsoft.com/appserviceteam/2018/06/26/announcing-general-availability-and-sovereign-cloud-support-of-managed-service-identity-for-app-service-and-azure-functions/

In this post, lets have a look at how easy it is to configure Managed Service Identity for an Azure Function and how it can be used together with Key Vault to secure sensitive information like Client Ids, Client Secrets and Passwords.

For example, when building an Azure Function which will interact with some data in SharePoint Online, we need a way to authenticate the Function with SharePoint. Two common methods used for authentication are 1) By creating an Add-In registration in SharePoint (appregnew.aspx) and 2) By using Azure AD authentication by creating an App Registration in Azure AD.

In both cases, we need to secure the ClientID and ClientSecret for the registration in such a way that only our calling code has access and any non-admin user browsing the Azure Function in the portal is prevented from seeing the sensitive data.  So let's see how we can do that using Managed Service Identity:

1) They very first thing you need to do is make sure that Managed Service Identity is configured for your Function App. You can do this simply by going to Function App Settings -> Managed Service Identity and ensuring that it is turned ON.

2) Create a Key Vault (or go to an existing one) and create two Secrets with names "ClientID" and "ClientSecret". You can also create additional Secrets relevant to your solution here.

3) Now we want our Azure Function App to have permissions to access the Key Vault. To do this, go to Access Policies -> Add New

4) Select the Function App as the principal and make sure under Secret permissions, it has at least the "Get" permission:

5) That's it in terms of the config! Now let's move on to the code to access the secured Client ID and Secret:

Make sure your Azure Function has the following NuGet packages:

Microsoft.Azure.KeyVault

Microsoft.Azure.Services.AppAuthentication

And here is an HTTP triggered .NET pre-compiled function which fetches the ClientId and ClientSecret from the Key Vault:

That's it! I was really surprised how easy MSI support for Azure Functions makes securing sensitive data. This way, any keys, secrets or passwords used by our solutions can be secured and retrieved without worrying about them getting in the wrong hands!

Quick note on pricing for MSI and Key Vault:

MSI is totally free to use and comes with the free version Azure Active Directory. The cost for storing secrets in the Key Vault is charged by number of access operations but it is pretty cheap as well. You could even go a step further and use caching in your code to reduce the number of access operations.

Get/Set SharePoint Online Tenant properties with CSOM

SharePoint Online Tenant properties are key/value pairs which can be used to set custom configuration settings on the tenant. These properties can then be consumed by SharePoint Framework components or any other type of customisation.

Here is some quick code I have put together to work with SharePoint Online tenant properties using CSOM.

The important thing to note here is that when setting the properties, we can only use the context of an App Catalog site (either tenant level or site collection level)

When getting the properties, the context of any site can be used.

Set SharePoint Online Tenant Properties in the App Catalog using CSOM:

Get SharePoint Online Tenant Properties using CSOM:

Note: While working with this code, I noticed SharePoint Online Tenant properties are stored as a web property bag entry in the root site of the App Catalog site collection. The properties are serialized to a JSON string and stored in the property bag entry with the key "storageentitiesindex":

(click to zoom)

SPFx: Calling back to SharePoint from an AAD secured Azure Function on behalf of a user

This post is part of a series where we explore consuming Azure AD secured Azure Functions from SharePoint Framework components. Articles in the series:

1) SharePoint Framework: Calling AAD secured Azure Function on behalf of a user
2) SharePoint Framework: Calling Microsoft Graph API from an AAD secured Azure Function on behalf of a user
3) Calling back to SharePoint from an AAD secured Azure Function on behalf of a user (this post)

The functionality shown in the post is preview only and not be used in production at this time.

In the previous post, we were successfully able to call the Microsoft Graph API from an AAD secured Azure Function and return data back to the SharePoint Framework web part.

Now in this post, lets see how we can make a call back to SharePoint on behalf of the logged in user from the Azure Function. We will only focus on the code in the Azure Function here, to fully understand the set up and auth process, I recommend you check out the previous posts in the series.

Updates to the Azure AD app registration:

In order to make a call back to SharePoint, we will need to add a Client Secret to the Azure AD app registration. Skip this step if you have already done this as part of the previous post.

We will also need to add the Office 365 SharePoint Online permissions scope to the Azure AD app registration. For this post, I am selecting the "Read and write items in all Site Collections" delegated scope. You can select the scope according to the operations you want to perform in SharePoint

Don't forget to grant the permissions again as a subscription admin. This is so that each user does not have to do this individually:

Here is what we are going to do in the code:

When the Azure Function executes, we already have an access token sent by the SharePoint Framework AadHttpClient in the Authorization header. This access token has the "user_impersonation" scope which only allows it to access the Azure Function. It cannot be directly used to call back to SharePoint.

In order to obtain new access token that will work with SharePoint, we will have to request it using the existing access token.

Once this function is called from the SharePoint Framework, we are able to get the data back to the web part:

Thanks for reading!

SPFx: Calling Microsoft Graph API from an AAD secured Azure Function on behalf of a user

This post is part of a series where we explore consuming Azure AD secured Azure Functions from SharePoint Framework components. Articles in the series:

1) SharePoint Framework: Calling AAD secured Azure Function on behalf of a user
2) Calling Microsoft Graph API from an AAD secured Azure Function on behalf of a user (this post)
3) SharePoint Framework: Calling back to SharePoint from an AAD secured Azure Function on behalf of a user

The functionality shown in the post is preview only and not be used in production at this time.

In the previous post, we were successfully able to call an AAD secured Azure Function from a SharePoint Framework web part.

Now once we are in the Function, lets see how to make a call to the Microsoft Graph on behalf of the logged in user. We will only focus on the Azure Function here, to fully understand the set up and auth process, I recommend you check out the previous post.

Updates to the Azure AD app registration:

In order to call the Microsoft Graph, we will need to add a Client Secret to the Azure AD app registration.

We don't need to add any new permission scopes for the purposes of this post as we are going to make a call to the /v1.0/me endpoint which requires the User.Read permission. According to the SPFx docs, if we exchange the SPFx generated token for a MS Graph token, it will automatically have the User.Read.All permission scope.

If you want to do anything beyond this with the Microsoft Graph, you will need to add the relevant permissions scope and grant permissions to it. In the next post, we will see how to do this by granting permissions to the "Office 365 SharePoint Online" permissions scope.

Here is what we are going to do in this post:

When the Azure Function executes, we already have an access token sent by the SharePoint Framework AadHttpClient in the Authorization header. This access token has the "user_impersonation" scope which only allows it to access the Azure Function. It cannot be directly used to call the Microsoft Graph.

In order to obtain new access token that will work with the Microsoft Graph, we will have to request it using the existing access token. Once we have the new token, we are able to make a call to the Microsoft Graph:

Once this function is called from our SharePoint Framework web part, we are able to get data back from the graph:

Thanks for reading!

Azure Functions: Add a message to a storage queue after a delay

I was looking at a specific problem today dealing with Azure Functions and adding messages to storage queues: I needed my Function to add a message to an output queue in order to trigger another function, but the challenge was, the message should not get added immediately and the second queue trigger function should not fire immediately as well.

We needed a delay between the completion of the first function and execution the second queue triggered function.

A not-so-great way of achieving this would be to add a Thread.Sleep before the message is added to the output queue but we really wanted to avoid that as it would keep the function running and would not be a truly "serverless" way of doing things.

I had a look at the visibilityTimeout setting in the host.json file but turns out it is meant for configuring the delay after which a retry is made when a function fails: https://docs.microsoft.com/en-us/azure/azure-functions/functions-host-json#queues

Fortunately, Jeff Hollan on twitter suggested a nice solution for this which utilised the initialVisibilityDelay property of the CloudQueue.AddMessage function. The great thing is this works seamlessly with Azure Function output bindings so we don't have to use the SDK ourselves.

Here is a sample of how my final code looks and it works pretty great!

Hope you find this useful!

Working with SharePoint Online Hub sites using CSOM

With SharePoint Online Hub sites launched for Targeted release tenants, here is some quick code I put together to work with them using CSOM:

1) Register a Hub site, Connect a site to a Hub site, Disconnect a site from a Hub site and Unregister a Hub site:

2) Grant and Revoke specific users rights to connect sites to a Hub site:

When a Hub site is registered, it is public by default. Any user is able to connect their site to the hub site. If you want only a specific set of users to be able to connect their site to the Hub site, you can grant "Join" rights to these users:

Hope this helps!

SharePoint Framework: Calling AAD secured Azure Function on behalf of a user

This post is part of a series where we explore consuming Azure AD secured Azure Functions from SharePoint Framework components. Articles in the series:

1) SharePoint Framework: Calling AAD secured Azure Function on behalf of a user (this post)
2) Calling Microsoft Graph API from an AAD secured Azure Function on behalf of a user
3) SharePoint Framework: Calling back to SharePoint from an AAD secured Azure Function on behalf of a user

The functionality shown in the post is preview only and not be used in production at this time.

Recently, after long last, the support for easily calling Azure AD secured custom APIs was released in the latest version of the SharePoint Framework (v1.4.1). Here are the details if you want to learn more: https://docs.microsoft.com/en-us/sharepoint/dev/spfx/use-aadhttpclient

In this post, let's have a look at how to secure our custom API (Azure Function) with Azure AD and then call the custom API from within a SharePoint Framework web part on behalf of the currently logged in user. We will be able to get the current user identity/claims in the custom API to know which user made the call to the Azure Function.

So let's quickly jump into how we are going to achieve this:

1) Create an Azure AD app registration

Go to Azure AD > App registrations > New application registration and create a new app registration. I am calling my app "User Details Custom API for SPFx"

By default the app registration will have the Sign in and read user profile scope on the Windows Azure Active Directory API. For the purpose of this post, those permissions are enough for us. We don't need to modify anything here right now.

Click on Properties and copy the App ID URI of the app registration. We will need this later in the SharePoint Framework web part.

As a subscription admin, Grant permissions to the App registration for all users so that each user does not have to do this individually:

2) Create an Azure Function App and configure it

Go to App Services > Add > Function App and create a new Azure Function App which we will use to host our Azure Function

Once the Function App is created, we need to secure it with our Azure AD app registration.

Go to Function App > Platform Features > Authentication / Authorization

In the Authentication / Authorization pane, for "Action to take when request is not authenticated" select "Log in with Azure Active Directory".

For Authentication Provider, click on Azure AD > Advanced and for Client ID, paste the Client ID (Application ID) of our Azure AD app registration we created earlier.

In Allowed Token Audiences, add the App ID URI of the app registration we copied in Step 1

Click Ok and Save the Configuration.

Go to Function App > Platform Features > CORS and add the SharePoint Online domain from which your SPFx webpart will make a call to the Azure Function.

Click on Save.

3) Create the Azure Function

Now let's actually create the Azure Function which we will deploy to the Function App as our custom API.

Using Visual Studio 2017, I have created a precompiled .NET Framework Azure Function project. As we are going to use this function as an API, I have selected an Http Triggered function:

Notice that the Authorization level for the function itself is set to Anonymous. This is because we are using Azure AD at the Function App level to secure it.

All this function does is returns the claims of the current authenticated user in JSON format.

Publish the function to the Azure Function App we created earlier.

4) Create the SharePoint Framework web part

Before going ahead with this step, make sure you have the latest version of the SharePoint Framework yeoman generator (1.4.1 at the time of this writing) This page should contain all the current versions of the generator, npm and node supported by the SharePoint Framework: https://docs.microsoft.com/en-us/sharepoint/dev/spfx/set-up-your-development-environment

Once you have all the latest packages, create the SPFx web part with yo @microsoft/sharepoint

To keep it simple, I am making it a tenant scoped solution with no JavaScript framework.

5) Request permissions for the SPFx web part

Once the SPFx web part solution is created, navigate to the config/package-solution.json file and add the webApiPermissionRequests property:

The resource will be the name of the Azure AD app registration we used to secure our Azure Function and the scope will be user_impersonation as we want to make a call on behalf of the current user.

6) Using AadHttpClient to call the custom Azure Function

Now in your SPFx webpart, include the following imports:

and the code to use the AadHttpClient to make a request to your custom Azure Function:

To display the table properly, add the following to the .scss file of your web part:

7) Installing and running the SPFx package 

Since we are going to run the SPFx solution in debug mode, we will run the commands without the --ship or --production switch. This will enable us to debug the solution locally.

Run the following commands to build and package your solution:

gulp build

gulp bundle

gulp package-solution

Start local debugging with

gulp serve --nobrowser

Now, upload the .sppkg file from the sharepoint/solution folder to the App Catalog:

Select the checkbox and Click on Deploy.

8) Granting permissions using the SPO Admin API management page

After deploying the package to the app catalog, as a SharePoint Administrator, navigate to the new SharePoint Online Admin centre and go to the API management section. You will notice the permissions we requested from the solution package can be approved from here. 

Approve the permissions before moving to the next step

9) Add web part to page

 

Now go to any modern page and add your web part to it. Since we have deployed a tenant scoped solution, no need to install it individually on each site.

This is probably my least favourite part of the process. You will need to enable pop-ups so that SPFx and the underlying ADAL.js can authenticate the current user with the custom API.

Once you have enabled the popup and refreshed the page, the web part should start displaying correctly!

The current user identity and claims coming through will be what we have sent from the Azure Function!

Hope this helps :) As always, the code from this post is available on GitHub: https://github.com/vman/spfx-azure-function-custom-api