In Azure, an App Service plan serves as the underlying infrastructure container for your web applications. It defines the region, operating system (Windows or Linux), and the set of compute resources (CPU, RAM, and storage) available to the apps running within it. Essentially, it represents the ser…In Azure, an App Service plan serves as the underlying infrastructure container for your web applications. It defines the region, operating system (Windows or Linux), and the set of compute resources (CPU, RAM, and storage) available to the apps running within it. Essentially, it represents the server farm backing your App Service.
**Provisioning**
When provisioning a plan, the most critical decision is the **Pricing Tier (SKU)**. This selection dictates:
1. **Hardware:** The power of the underlying Virtual Machines (e.g., Core counts, Memory).
2. **Features:** Access to specific capabilities like Custom Domains, SSL certificates, Deployment Slots, and VNet Integration.
3. **Cost:** Tiers range from **Free/Shared** (for development on shared infrastructure) to **Basic/Standard/Premium** (dedicated production hardware) and **Isolated** (dedicated environments for high security).
**Configuration**
Post-deployment configuration focuses primarily on capacity management:
* **Scaling Up (Vertical):** You alter the plan's pricing tier to add more power or unlock features (e.g., moving from Standard to Premium).
* **Scaling Out (Horizontal):** You increase the number of VM instances running your app. In Standard tiers and above, you can configure **Autoscale** settings, allowing Azure to automatically add or remove instances based on metric thresholds (like CPU usage) or schedules.
A single App Service plan can host multiple web apps, allowing them to share resources to save costs, provided the apps do not exceed the plan's aggregate resource limits.
Provision and Configure App Service Plans
What is an App Service Plan? An App Service Plan acts as the container and definition of compute resources for Azure Web Apps, API Apps, and Mobile Apps. Analogous to a server farm in on-premises server management, it defines the location, size, and features of the web server farm that hosts your application.
Why is it Important? The App Service Plan is the primary driver of cost and capability. It determines how much you pay, how much hardware (CPU/RAM) is reserved for your apps, and which advanced features (like deployment slots, VNet integration, or traffic manager) are unlocked.
How it Works When provisioning a plan, you configure three main settings: 1. Region: The physical Azure datacenter (e.g., West Europe). 2. Operating System: Windows or Linux. 3. Pricing Tier (SKU): The specific category that dictates hardware and features.
Understanding Pricing Tiers (SKUs) Shared/Free: Runs on shared infrastructure with other Azure customers. CPU is limited by quotas. Good for development, but does not support custom domains or SSL. Basic: Dedicated instances. Supports Custom Domains and SSL. Does not support Autoscaling. Standard: The entry level for production workloads. Includes Autoscaling, Deployment Slots (up to 5), and automated backups. Premium: Faster processors, SSD storage, increased scale-out limits, and support for Availability Zones. Isolated: Runs in an App Service Environment (ASE) on dedicated hardware for maximum security and VNet isolation.
How to Answer Questions on the Exam For AZ-104, questions often present a scenario and ask for the most cost-effective solution or the correct configuration steps.
Exam Tips: Answering Questions on Provision and configure App Service plans 1. Shared Resources Strategy: You can host multiple Web Apps in a single App Service Plan to save money. However, verify that the apps are in the same Region and use the same OS. Because they share the plan's CPU and RAM, one resource-heavy app can degrade the performance of others. 2. Scale Up vs. Scale Out: - Scale Up: Changing the SKU (e.g., from Basic to Standard) to get more CPU, RAM, or specific features like Deployment Slots. - Scale Out: Increasing the number of VM instances (e.g., running 2 instances of the Standard plan) to handle high load. 3. Feature Gates: Memorize the minimum tier for key features. If a question requires Deployment Slots or Autoscaling, the answer is usually Standard. If the question requires VNet injection or high isolation, look for Premium or Isolated. 4. Moving Apps: You can move an app between plans, but the destination plan must typically reside in the same Resource Group and Region as the source.