1.Overview & Architecture¶

Overview¶

SLA 99,95% starting at Basic and over
App Service Plan is made of:
- Size:
  - Defines a set of compute + memory resources
  - small, medium, large
- Tier:
  - Defines the available features
  - Free, Shared, Basic, Standard, Premium, Isolated
App Service Plan Size:
- = defines the scale unit
- Small: 2 Core, 8GB
- Medium: 4 Core, 16GB
- Large: 8 Core, 32GB
App Service Plan VM Type:
- Free, Shared, Basic, Standard, Premium: = same VM type
- Premium v2: based on Dv2
- Premium v3: based on Dv4
App Service Plan Pricing Tier:
- Free, Shared:
  - App is hosted on a shared VM instance (= shared worker)
  - VM is shared with multi-apps & multi-customers
- Basic, Standard:
  - App hosted on a dedicated VM instance(s)
  - Can host multiple apps
  - Support Web App for containers in the Linux runtime
- Premium v3:
  - App hosted on a dedicated VM instance(s)
  - Can host multiple apps
  - Support for Vnet connectivity
  - Support for Linux containres
  - Support for Windows containers
- Premium v2:
  - App hosted on a dedicated VM instance(s)
  - Can host multiple apps
- ASE v3 (= Isolated v2):
  - isolated and dedicated environment
    - App hosted on dedicated VM instance(s)
    - Placed on dedicated Azure Vnet
  - Public preview 01/11/20
- ASE v2 (= Isolated v1):
  - Provides a fully isolated and dedicated environment for securely running App Service apps
    - App hosted on dedicated VM instance(s)
    - Placed on dedicated Azure Vnet
  - Support:
    - Windows web apps
    - Linux web apps
    - Docker containers
    - Mobile apps
    - Functions
  - Appropriate for application workloads that require:
    - Very high scale.
    - Isolation and secure network access.
    - High memory utilization
  - ASE comes with its own pricing tier, learn how the Isolated offering helps drive hyper-scale and security
  - Can be deployed into Availability Zones (AZ) using zone pinning
  - Dedicated environment:
    - Can host 100 App Service Plan instances
- ASE v1:
  - You need to manage all of the resources manually

Pricing¶

Free & Shared:
- metered on a per App basis
Basic -> Isolated:
- Billed on a per second basis
- each VM instance in the App Service plan is charged
  - regardless how many apps are running on them
- Tier: differs from features offered
- Charged even when stopped
- Includes 20MB Azure SQL free of charge for the first year
Premium v2:
- Support for MSDN Dev/Test subscription
Premium v3:
- Compatible with 1 or 3Y RI (starting 01/11/20)
- Support for MSDN Dev/Test subscription
ASE v3 (= Isolated v2):
- no per instance stamp fee
- each worker is charged (a worker run an app)
ASE v2 (= Isolated v1):
- flat monthly rate
- - cost per instance
- each worker is charged (a worker run an app)
- Compatible with 1Y RI
ASE v1:
- you pay for each vCPU allocated
- That includes vCPUs used for front ends or workers that aren't hosting any workloads
- Default maximum-scale size of an ASE is 55 instances
- Includes workers and front ends
App Service Domain
App Service Certificate (x509)
SSL Connection:
- No charges for SNI-based SSL
- Std & Premium includes 1 IP-based SSL at no charges

Architecture¶

App Service:
- The roles that handle incoming HTTP or HTTPS requests are called front ends
- The roles that host the customer workload are called workers
- In multi-tenant:
  - All the roles in an App Service deployment exist in a multitenant network
  - front ends are shared, workers are dedicated (= dedicated VM)
  - Webspace:
    - Is a deployment unit hosting 1..n app service
    - App services are deployed into one of the deployment units in the Azure infra
- In ASE: front ends and workers are dedicated
Containers:
- Linux Apps runs in its own container
- Windows container app runs in its own container
- No access to the host outside the container is provided
ASE v3:
- Isolated and dedicated environment
- Build on VMSS
- Internal ASE infra deployed in separate Azure-controlled network
  - Eliminates ASE management traffic in customer network
- Endpoints injected in customer network
ASE v2:
- Isolated and dedicated environment
- Composed of front ends and workers.
- Front ends are responsible for HTTP/HTTPS termination and automatic load balancing of app requests within an ASE.
- Front ends are automatically added as the App Service plans in the ASE are scaled out
- Workers are roles that host customer apps:
  - One vCPU/3.5 GB RAM
  - Two vCPU/7 GB RAM
  - Four vCPU/14 GB RAM
File Access:
- Each customer's subscription has a reserved directory structure on a specific UNC share within a data center
  - => same UNC share for all the App Service within the same subscription
  - directories are available for read and write access at runtime by the app's application code
  - App code can list OS dir structures and read common files
- Local Drives:
  - OS = D:\
  - User drive = C:\ => = UNC share
    - App Service reserves a chunk of space for app-specific temporary files
      - Not intended to be used directly by the application code
      - Intented for IIS & app framework
    - Since it's a share all the files are available to all the app instances at a time
  - Internal App Svc drive:
    - Contains the App svc packages
    - Is not accessible to customers
- Network shares:
  - Allow to store the user content, based on UNC share like \\<host>\<path>\<filename>
  - UNC = Universal Naming Convention
  - Make it easy to work with front end behind load balancer
  - All of the file content for a single customer's subscription is always placed on the same UNC share
  - The C:\ drive is mapped to UNC shares