Azure certifications are usually focused on selecting the most suitable service or option for a specific situation.
Unfortunately, you have to memorize some of the differences between App Service Plans to be able to solve some types of the questions related to selecting the suitable App Service Plan for a specific situation.
App Service Plans
Below list is the App Service Plans that you are going to choose from sorted from lowest to highest cost.
- FREE (F1)
- SHARED (D1)
- BASIC (B1, B2, B3)
- STANDARD (S1, S2, S3)
- PREMIUM (P1v2, P2v2, P3v2)
- ISOLATED* (I1, I2, I3)
As an azure architect you should always focus on selecting lowest cost of the selected resource that achieve the required features.
You might be asked to select the most suitable App Service Plan to satisfy number of instances when scaled out or the one that supports SSL or you may be required to add custom domain to your app service.
You have various aspects to focus on when choosing the most suitable App Service Plan for your app service
If you need to connect to your app service to your domain, You have many options to achieve that. Free plan is the only app service plan that doesn’t support custom domain and all other app service plan support it.
Scaling out your app service
Scaling is one of the most powerful tools of App Service. Sometimes you are required to provide a solution for your application to scale in some situations, let’s say CPU high usage, and you have to select to optimum solution for your scenario. Free and Shared plans don’t support scaling out. For the other plans you would select the plan based on the number of instances you want your app servicer to have in case of scaling. You would select the plan as follows:
- Basic plan gives you up to 3 instances of app services but without the possibility of autoscaling
- Standard plan gives you up to 10 instances of app services and autoscaling supported
- Premium plan gives you up to 30 instances of app services and autoscaling supported
- Isolated plan gives you up to 100 instances of app services and autoscaling supported
App service has a great feature called deployment slots that allows you to deploy new releases with zero down time. To be able to use deployment slots in your app service you have to use Standard, Premium or Isolated plan.
SLA (Service Level Agreement)
Free and shared plan don’t support SLA but all other plans have 99.95 % SLA.