Tutorial / Cram Notes
Scaling in Azure App Service is a feature that allows you to handle increases or decreases in your web application’s demand. There are two types of scaling – vertical (scaling up and down) and horizontal (scaling out and in). By adjusting the App Service Plan, you can ensure that your application performs efficiently and cost-effectively.
Vertical Scaling (Scaling Up/Down)
Vertical scaling involves changing the tier of your App Service plan to a higher or lower performance level. As you move up tiers, you get more CPU, memory, disk space, and additional features like staging slots and traffic management.
How to Configure Vertical Scaling:
- Navigate to the Azure portal at https://portal.azure.com.
- Go to the “App Services” and select the specific App Service you want to configure.
- In the left navigation panel, under “Settings”, click “Scale up (App Service plan)”.
- You will see a list of pricing tiers, which indicate different levels of performance and features.
- Click on the tier you want to scale up to, then review the new features and costs.
- Confirm your selection to scale up your App Service Plan.
Horizontal Scaling (Scaling Out/In)
Horizontal scaling is the process of adding or removing instances of your web application to match demand.
How to Configure Horizontal Scaling:
- In the Azure portal, navigate to your App Service.
- In the left navigation panel, under “Settings”, click “Scale out (App Service plan)”.
- Here, you can choose between two types of scaling:
- Manual Scaling: You specify the number of instances that you need.
- Autoscaling: Azure will automatically scale in or out based on metrics such as CPU usage or HTTP queue length.
Configure Manual Scaling:
- Select “Custom” under “Scale mode”.
- Move the slider or enter the number of instances in the textbox to indicate how many instances you need.
- Click “Save” to apply the changes.
Configure Autoscaling:
- Choose “Autoscale” for Scale mode.
- Create a new rule or select an existing one.
- Choose the metric you want to use for scaling (like CPU percentage).
- Set the minimum and maximum number of instances.
- Define the threshold for the metric that will trigger a scale action.
- Configure scale-in and scale-out rules – specifying the number of instances to remove or add when the rule is triggered.
- Save the autoscale settings.
Considerations:
When configuring scaling settings, it’s important to keep a balance between performance and cost. Here’s a simple comparison table of factors to consider:
| Factor | Vertical Scaling | Horizontal Scaling |
|---|---|---|
| Cost | Potentially higher | Incremental |
| Performance | Can increase drastically | Increases linearly |
| Downtime | Possible during change | Minimal to none |
| Flexibility | Less flexible | Highly flexible |
| Complexity | Simple to configure | More complex to set up |
Examples:
Example 1: Manual Scaling
For a campaign website that expects consistent traffic over the weekend, you might opt for manual scaling, increasing instances from 2 to 5.
Example 2: Autoscaling
For an e-commerce site with traffic that surges on Black Friday, autoscale settings are useful. An autoscale condition could be set to increase instances from 3 to 10 when CPU usage exceeds 70% for 10 minutes.
In conclusion, configuring scaling settings in an Azure App Service plan is a crucial task for Azure Administrators to ensure applications are running efficiently. The scaling option to choose depends on the nature of the application, traffic patterns, and cost considerations. Properly managing scaling ensures that performance targets are met while controlling costs, making it an essential skill covered on the AZ-104 Microsoft Azure Administrator exam.
Practice Test with Explanation
True/False: App Service Plans support auto-scaling based on a schedule.
- Answer: True
Explanation: App Service Plans can be configured to scale out or in based on a predefined schedule.
True/False: The App Service Plan can only be scaled manually through the Azure Portal.
- Answer: False
Explanation: App Service Plans can be configured for both manual and autoscaling, including scaling based on metrics like CPU usage or schedule.
In which of the following App Service plan tiers can you configure autoscaling based on CPU usage?
- A) Free
- B) Shared
- C) Basic
- D) Standard
- E) Premium
Answer: D) Standard, E) Premium
Explanation: Autoscaling based on CPU usage or other metrics is supported in the Standard and Premium tiers of App Service Plans.
True/False: You can configure autoscaling to scale out to 20 instances in an App Service Plan on the Free tier.
- Answer: False
Explanation: The Free tier of App Service Plans has limitations on scaling capabilities and does not allow for this number of instances.
What is the minimum number of instances you must have in an App Service Plan to configure autoscaling?
- A) 0
- B) 1
- C) 2
- D) 3
Answer: B) 1
Explanation: Autoscaling can be configured with just one instance as the minimum; scale-out settings will add more instances based on defined rules or schedules.
True/False: You can use Azure Monitor Autoscale to configure and manage scaling for an App Service Plan.
- Answer: True
Explanation: Azure Monitor Autoscale is a service that can be used to set up and manage scaling for Azure App Service Plans.
Which of the following metrics can be used for autoscaling an App Service Plan? (Select all that apply)
- A) Disk Queue Length
- B) CPU Percentage
- C) Memory Percentage
- D) HTTP Queue Length
Answer: B) CPU Percentage, C) Memory Percentage, D) HTTP Queue Length
Explanation: Autoscaling for App Service Plans can be based on metrics such as CPU Percentage, Memory Percentage, and HTTP Queue Length. Disk Queue Length is not a supported metric for autoscaling.
True/False: Autoscaling settings configured for an App Service Plan will also apply to all the apps within that plan.
- Answer: True
Explanation: When autoscaling settings are applied to an App Service Plan, they affect all apps associated with that plan because they share the same compute resources.
What feature must an App Service Plan have to support autoscaling actions like “Scale Up” and “Scale Out”?
- A) Always On
- B) Custom Domains
- C) Multiple slots
- D) Elasticity
Answer: D) Elasticity
Explanation: Elasticity is the feature of an App Service Plan that allows it to automatically “Scale Up” (change to a higher pricing tier) or “Scale Out” (add more instances).
True/False: Azure Function Apps in a Consumption Plan automatically scale without the need to configure an App Service Plan scaling setting.
- Answer: True
Explanation: Azure Function Apps in a Consumption Plan are designed to scale automatically based on demand, without the need for manually configuring scaling settings in an App Service Plan.
True/False: It is possible to set up autoscaling based on custom metrics in Azure App Services.
- Answer: True
Explanation: Azure App Services allows you to set autoscaling rules based on custom metrics aside from the built-in metrics like CPU and memory usage.
When configuring autoscaling for an App Service Plan, which of the following settings can be specified? (Select all that apply)
- A) Maximum and minimum number of instances
- B) Cooling-off period before scaling in
- C) Specific days to exclude from scaling
- D) Default time zone for scheduled scaling
Answer: A) Maximum and minimum number of instances, B) Cooling-off period before scaling in
Explanation: When setting up autoscaling, you can specify the maximum and minimum number of instances for scale-out and scale-in actions, as well as a cooling-off period, which is the amount of time to wait before performing another scaling action. Specific days to exclude from scaling and setting a default time zone for scheduled scaling are not part of the current configuration settings for autoscaling in Azure App Services.
Interview Questions
What is an App Service plan?
An App Service plan is a collection of resources used to host one or more Azure web apps, mobile app backends, and RESTful APIs.
What are the benefits of configuring scaling settings in an App Service plan?
Configuring scaling settings in an App Service plan ensures that the app’s availability and performance are maintained by automatically scaling up or down the resources as per the app’s demands.
How do you configure scaling settings in an App Service plan?
You can configure scaling settings in an App Service plan by following the steps outlined in the Azure portal.
What is the purpose of the “Scale up” option in the App Service plan management blade?
The “Scale up” option allows you to select the pricing tier that meets your app’s demands.
What is the “Scale out” option in the App Service plan management blade?
The “Scale out” option allows you to add additional instances to your App Service plan to handle increased app traffic.
Can you configure autoscale settings in an App Service plan?
Yes, you can configure autoscale settings in an App Service plan.
What are the available scaling options for autoscale in an App Service plan?
The available scaling options for autoscale in an App Service plan include CPU usage, memory usage, HTTP queue length, and custom metrics.
Can you disable autoscale in an App Service plan?
Yes, you can disable autoscale in an App Service plan.
Can you configure multiple autoscale rules for an App Service plan?
Yes, you can configure multiple autoscale rules for an App Service plan.
What happens when an autoscale rule is triggered in an App Service plan?
When an autoscale rule is triggered in an App Service plan, additional instances are added to handle the increased traffic or resources are scaled up to handle the increased load.
What is the maximum number of instances you can add to an App Service plan?
The maximum number of instances you can add to an App Service plan depends on the pricing tier you choose.
How can you monitor the scaling behavior of an App Service plan?
You can monitor the scaling behavior of an App Service plan by using Azure Monitor or the Azure portal.
Can you manually scale up or down an App Service plan?
Yes, you can manually scale up or down an App Service plan based on the app’s demands.
How can you estimate the cost of an App Service plan with autoscale settings?
You can estimate the cost of an App Service plan with autoscale settings by using the Azure pricing calculator.
What are the factors you should consider when configuring autoscale settings for an App Service plan?
When configuring autoscale settings for an App Service plan, you should consider factors such as app usage patterns, CPU and memory usage, and HTTP queue length.
Great insights on configuring scaling settings! Helped me a lot for my AZ-104 prep.
Can someone explain the difference between horizontal and vertical scaling in Azure App Service?
I’m confused about the difference between manual and automatic scaling settings. Can anyone help?
I found the explanation on scale-out rules really useful. A must-read for anyone looking to ace the AZ-104 exam!
Any tips on best practices for configuring scale-in settings?
How do you monitor the effects of scaling changes? I want to ensure optimal performance.
Thanks for the detailed walkthrough!
@10, also consider setting up alerts on different metrics to get notified of any anomalies.