What should User-Agent be set to when using Microsoft Graph API?

Question

I am currently working on an application that makes requests using the .NET SDK for the Microsoft Graph API. Specifically to retrieve information about users and their OneDrives.

Microsoft throttles API requests by returning an HTTP 429 status code, and I have implemented a back-off using the Retry-After header. I have noticed however that I seem to be getting throttled after only a handful of requests.

I have also been using Microsoft Graph Explorer to test some of my API calls and have noticed that I never seem to get a 429 response when accessing the API via that method. After also seeing reports of people having issues with the OneDrive client on Linux that they managed to work around by changing their User-Agent header, I thought maybe I needed to set a User-Agent for my requests.

The result is that it seems that if I set the User-Agent header to be something like Mozilla/5.0 then all the throttling issues seem to disappear. I have searched high and low and so far haven't managed to find any documentation on what a valid User-Agent should be, and I would prefer to avoid making my app impersonate a browser, so I wondered whether there was any guidance or documentation around that I might have missed?

For instance, a User-Agent of Mozilla/5.0 seems to result in no throttling, but MyApp/1.0 results in throttling.

Answer 1

There isn't any guidance on the User-Agent header and to be honest, I'm not sure why this would have any effect on throttling.

Throttling in Microsoft Graph is handled by the underlying service you're interacting with. For example, the /notes/ endpoint throttling is governed by OneNote while /messages is governed by Exchange.

In most cases, OneDrive will throttle by number of concurrent requests, per app, per user. So using Delegated permissions, your app should generally be able to concurrently upload 4 files without a problem. Any more than that and you will start to see 429 responses.

Answer 2

there are some best-practices from Microsoft to handle throttling:

https://docs.microsoft.com/en-us/sharepoint/dev/general-development/how-to-avoid-getting-throttled-or-blocked-in-sharepoint-online#how-to-decorate-your-http-traffic-to-avoid-throttling

you should decorate your http user-agent as following:

NONISV|CompanyName|AppName/Version

Identify as NONISV and include Company Name, App Name separated by a pipe character and then adding Version number separated with a slash character

or

ISV|CompanyName|AppName/Version

Identify as ISV and include Company Name, App Name separated by a pipe character and then adding Version number separated with a slash character