Create and configure a Web App, deploy code from GitHub repository, add staging environments using deployment slots and swap between testing and production environments in Azure. Posted by Dimitris Krallis April 5, 2020 April 14, 2020 Posted in Uncategorized Tags: Azure, Cloud, Deployment slots, swap, Web Application. Azure Deployment Slots – a brief introduction. Deployment Slots are a capability of Azure Web Apps (previously known as Azure Websites). They are only available when you’re using a Standard or Premium pricing plan. If you go into the “Settings” area of your web app, you can click into “Deployment Slots” and from here create a slot. Web Apps for Containers allows you to use Linux-based containers to deploy your application into an Azure App Services Web App. This way, you can make sure that the environment that you use locally, is exactly the same as the one in the cloud. If this is the case, should the queue connectionstring be moved from app.config into Azure Website config so my Staging and Production slots can run on different queues? Azure azure-web-app-service azure-webjobs. If you choose Azure Repos, you can set up your web app’s CI (Continuous Integration) system with an Azure Repo, which is part of Microsoft’s Azure DevOps services (formerly known as VSTS, aka Visual Studio Team Services). You will have options for using App Service as a Kudu build server or Azure Pipelines as your CI build system.

Back when we all used Azure Cloud Services for running websites and backend worker tasks, we had the fabulous concept of deployment slots. Since January 2014, this concept was also introduced in the offering than called Azure Websites. Now, in Azure App Services Web Apps, the concept is still alive.

What is a deployment slot?

Basically, a deployment slot is another Web App that runs next to your original one. This means that you could create a deployment slot for your production environment and call that the pre-production slot, or staging slot, as in the illustration below:

At the time of this writing, you can create up to:

• 4 slots for Web Apps in the standard tier in addition to production
• 19 slots in the premium tier in addition to production

Note that a deployment slot is a fully fledged Web App, hosted in the same pricing tier as the Web App it is spawned from. Therefore it will incur costs.

Benefits

Using a deployment slot can provide the following benefits:

• Test it in pre-production - you can deploy a pre-production version of your site and test it before it goes into production. You can do functional and automated testing on this, and also use it to do performance testing, to make sure that everything is alright without testing in production
• Easily deploy - once you are happy that your website in the staging slot works as expected, you can use the swap function (or even use Auto Swap) to get your version seamlessly in production.
  • What happens here, is that the Virtual IP Address of the swap target (in my example the production slot) is re-pointed to the swap source (the staging slot) and vice versa.
  • Also, before the swap happens, the website in the staging slot is pre-warmed to make sure that the website is ready to go when you swap it
  • These mechanisms ensure that there is no downtime when you swap and makes for a great deployment mechanism
• Revert deployment - If for whatever reason, you’re not happy with the result of website now in production, you can easily revert back to the situation that was working before by swapping back to the staging slot

Limitations

• You cannot use linked resource management in a non-production slot
• You cannot scale out a non-production slot (meaning that you cannot scale the number of instances)

Traffic Routing

Traffic Routing (previously called testing in production), can help you with doing A/B testing (actual testing in production).

Azure Web App Deployment Slots Pricing Guide

You can set it up to route a percentage of all traffic to one or more deployment slots, as in the illustration below. By doing this, users are redirected to your deployment slot and they are testing in “production”.

Azure Web App Deployment Slots Pricing Strategy

Take advantage of deployment slots. It’s a simple enough mechanism to use with huge benefits. Try it out!