Overview

App Service Web Apps is a service for hosting web applications, REST APIs, and mobile back ends.
- Applications run and scale on Windows-based environments or Linux-based environments.
- It adds security, load balancing, auto-scaling, and automated management.
With App Service, you pay for the Azure compute resources you use.

Deployment Slots

When you deploy your app, you can deploy to a separate deployment slot instead of the default production slot when running in the Standard or Premium App Service plan tier.
Deployment slots are actually live apps with their own host names.
App content and configurations elements can be swapped between two deployment slots, including the production slot.
Deploying an app to a slot first and swapping it into production ensures that all instances of the slot are warmed up before being swapped into production.
- This eliminates downtime when you deploy your app.
- The traffic redirection is seamless, and no requests are dropped as a result of swap operations.
After a swap, the slot with previously staged app now has the previous production app.
- If the changes swapped into the production slot are not as you expected, you can perform the same swap immediately.
Each App Service plan tier supports a different number of deployment slots.
To scale your app to a different tier, the target tier must support the number of slots your app already uses.

WebJobs enables you to run a program or script in the same context as a web app, API app, or mobile app.
- There is no additional cost to use WebJobs.
A web app can time out after 20 minutes of inactivity.
- Only requests to the scm (deployment) site or to the web app's pages in the portal reset the timer.
- Requests to the actual site don't reset the timer.
If your app runs WebJobs, enable Always On to ensure that the WebJobs run reliably.
- This feature is available only in the Basic, Standard, and Premium pricing tiers.

It starts immediately when the WebJob is created.
- To keep the job from ending, the program or script typically does its work inside an endless loop.
- If the job does end, you can restart it.
It runs on all instances that the web app runs on.
- You can optionally restrict the WebJob to a single instance.
It supports remote debugging.