How accurate is the time in Azure Functions?

Question

I am working on a WPF application for a financial services company. Having accurate time is very important.

I will be using Azure Functions for the service layer that the applications communicate with. I need to know how much I can rely on the time accuracy provide by Azure Functions and any best practices. Are there any SLAs on the time accuracy that would help us address any regulatory concerns should they arise.

Does having a Premium Plan change anything?

Does hosting functions on a App Service Virtual Machine change anything?

I read that Azure utilizes time sync on servers and just want to confirm that this is true for Azure Functions
https://azure.microsoft.com/en-us/blog/time-synchronization-for-financial-services-in-azure/
https://learn.microsoft.com/en-us/azure/virtual-machines/windows/time-sync

Answer 1

Hi @Andrew Hawes

Apology for the delay in responding.

The beneath compute infrastructure will remain the same for any of the Azure services. Most of the time it will provide the time accuracy but there is no SLA for the same. You don't have control over the time accuracy that is provided by the azure function. In the very rare cases, there might be a clock drift issue that could cause the inaccuracy of the time. Azure Premium plan doesn’t change anything regarding the time accuracy.

VM would give you a bit more control as you can change how the time is being determined and you can even use your external time server if required. You can try a different configuration that is mention in the Linux and Windows doc to suit your specific needs for VM. As far as function is concerned you can run a function in a docker container on Linux. Docker uses the host machine clock and this thread talks more on syncing time with host.