Azure Deployment Slots with Post Implementation Testing

Question

Our company website will soon be hosted in an App Service in Azure. The website communicates with an API layer that also hosted in Azure and links to our internal systems and databases. The architecture at this level cannot be changed at this time and has quite a bit of background history, etc.

We are looking at implementing always on deployments using Deployment Slots in the App Service in Azure. The API layer will have non-breaking changes for each deployment and deploying the APIs will be the first part of any release, with the website following.

Is have a clear separation between our environments and the release will be tested in Dev, Test and Pre-Prod environments before the production deployment begins. Overall the whole process is fairly simple until it comes to post-implementation (PI) testing that is currently this is mandatory in our company.

We need to be able to test the production deployment prior to the customers using the site. Currently we feature toggle the site into maintenance mode unless its being accessed from a select IP address list. We now need to perform the PI testing on the new version of the site whilst the customer continues to use the older version of the site. I wasn't sure of the best way of achieving this.

One idea I did have is having a subdomain that links directly to the websites _staging deployment slot bypassing the deployment slot settings. In turn some logic in here could go direct to the API _staging deployment slot. This would give the option to post implement the change just prior to clicking the 'Swap' button to swap over the deployment slots.

I know the overall process isn't ideal, but at the moment this can't be changed. Does anyone have any thoughts or other suggestions on the above please?

Answer 1

Azure makes it easy to create deployment slots for App Services. It’s available in the Standard or Premium App Service plan mode. Deployment slots are actually live apps with their own hostnames. App content and configuration elements can be swapped between two deployment slots, including the production slot.

Azure customers can easily perform the following steps - Deploy the web application to an online deployment slot. - Run the tests on a deployment slot, within the live environment that potential testers are going to use. Testing environment and production environment exist side-by-side and provide the similar environment. - Perform an internal swapping of the IP addresses of both slots (via load balancing and traffic management for both the nodes — slots) - Update applications with zero downtime - Swap back to a previous version of your app instantly, with zero downtime for users.

References https://docs.microsoft.com/en-us/azure/app-service/deploy-staging-slots

The overall reason to have deployment slots enabled is that it helps your team to run live testing on the production environment, and in case there are some problems on the production slot, it lets you roll back the swap without having to take your application down for maintenance.