I want to enable Sticky session on Azure Pass Sitecore CD instances(multiple app services). Is this possible? If not, what are other options that I have?
Yes, it is possible, however, since you didn't specify if you are running a Scaled Out or multiple App Services for the CD instance, I am going to cover your options for that.
- Scaled Out
When you Scale Out, a Load Balancer will handle the traffic when a visitor access your website, and distribute the traffic to one of the instances of your Azure App Service. In order to avoid that your users jumps from instance to instance, you can use ARR Affinity which is enabled by default in Azure App Service.
- Multiple App Services
Using this approach, you won't have the benefit in have a Load Balancer automatically added in front of your CDs, so you will need to either add an Azure Application Gateway or use a third party solution for that. The Azure Application Gateway has the option to enable Cookie Based Affinity, just make sure it is enabled and you should be fine