Monday 7 November 2016

Introducing: SharePoint Online Public CDN Manager

Update 24th March 2017: This post was updated since the general availability of the Office 365 Public CDN. The SPO CDN Manager now supports the GA version of the Office 365 Public CDN.

The Office 365 Public CDN recently reached General availability. It allows static assets like images, JavaScript, CSS etc. to be hosted in a globally available CDN. Find out more about it here.

With the general availability, the Office 365 PowerShell and SharePoint Online CSOM were also updated with APIs which could be used to manage the Public CDN.

Although the APIs are handy, what was missing was a nice and simple GUI to manage the CDN settings. So I set out to create an app which would give a nice overview of all the CDN settings including folders in the tenant which have been configured as Origins, file types which have been set to be pushed to the CDN and finally a way to enable/disable the CDN.

Introducing the SharePoint Online Public CDN Manager:

Check it out now:

Checkout the code on GitHub:

As you can tell, the SharePoint Online Public CDN Manager can be used to:

1) Add/Remove CDN Origins i.e. SPO Libraries which will be used to store static assets.

2) Add/Remove File types. Which files will be pushed to the CDN.

3) Enable/Disable the CDN on a tenant.

4) Create the default CDN origins specified by the Office 365 Public CDN

The Implementation:

1) It is an MVC app which is Multi Tenant and hosted on the Azure App Service. It uses the March 2017 Release of SharePoint Online CSOM to talk to SharePoint.

2) For the UI, the Office UI Fabric core styles are used together with the Office UI Fabric JS Components

3) The app requires "Office 365 SharePoint Online" Full Control permissions on all site collections. This is because the CDN is a tenant wide setting and can be modified only by Tenant Administrators or SharePoint Administrators.

The app uses Delegated (User) authentication for every call to SharePoint so that only Tenant/SharePoint Administrators can access the CDN Properties:
So even if a user who is not an Admin lands on the page, they are not able to fiddle with the CDN settings.

Tenant vs Office365Tenant

Something interesting I came across while working on this. There are 2 classes available in CSOM now to manipulate tenant settings:



Both these classes have the Public CDN properties which can be used to manage the CDN. But the interesting this is that the Tenant class requires the Tenant Administration Url ( to instantiate but the Office365Tenant class can be instantiated by a regular site url in SharePoint Online. (

If a regular SharePoint site url is used to instantiate the Tenant class, you get an exception saying:

Current site is not a tenant administration site.

This is why I have used the Office365Tenant class. Checkout the code on GitHub for more details.

Workaround for Internet Explorer "Quirks":

The SPO CDN Manager has been tested on latest version of Chrome, Edge and IE. It works without any issues on Chrome and Edge.

But, to get it working on IE, you will have to add the remote site to IE's trusted sites.

Thanks for reading! Hope you find the SPO CDN Manager useful.


Unknown said...

Good post and very handy tool. I can see this tool being used massively !!

Unknown said...

Great post !!! Awesome.

Vipul Kelkar said...

Since most of the resources - CSS,JS code and images can be considered sensitive by most of the customers/organizations, have you come across any use case to actually implement this Office 365 public CDN in a SharePoint specific application as to what kind of files can be stored in this Office 365 CDN ? Probably just the SharePoint specific JavaScript libraries ?

Vardhaman Deshpande said...

Hi Vipul,

You are right and that is why Microsoft is also thinking about introducing a private version f the CDN where resources cannot be accessed without a valid access token.

As far as the public CDN goes, I have worked on a few projects where performance was key and the client was okay to make the intranet images anonymously accessible as long as the page load time was reduced.

Also, you have to remember that someone can visit these resources only if they know what the exact url is. But a valid concern none the less.


chris said...

We're running into issues with the CDN caching interfering with our development process. (On the Microsoft Tenancy, BTW). Our site is rendering the cached CDN files instead of the local ones (in a folder in the master page gallery) we're developing on. Is there a place we can put our custom files where they won't get cached by default? Is there a meta-tag or flag we can set to disable the CDN functionality temporarily during development?