Need to know whenever the instance count is reaching maximum instances(125) in application gateway of waf v2 sku.

Question

Need to know whenever the instance count is reaching maximum instances(125) in application gateway of waf v2 sku.

Murarisetty Yamuna 140

The current configuration of the application gateways includes recommendations such as utilizing the V2 SKU, enabling autoscale, and setting the maximum instance count to 125. As per MS Document each instance can uses a minimum of 10 capacity units for processing capability-got this from Instance count Reference: (https://learn.microsoft.com/en-us/azure/application-gateway/understanding-pricing#v2-skus). Then the maximum capacity units is 1250(125*10). This is my question:

To monitor instances approaching the maximum limit in application gateway , Is the metric signal "Current Capacity Unit " is the precise or not?
Is creating an alert on the capacity units with a threshold value of 940 (75%) is the precise solution for continuously monitoring instances, ensuring awareness as they approach the maximum limit?

NOTE: The aggregation type is average(this is only one option is giving in the alert creation), operation: count and Threshold value:940

GitaraniSharma-MSFT 49,856 Reputation points Microsoft Employee

2024-01-25T14:31:02.37+00:00

@Murarisetty Yamuna , Just checking in to see if you had a chance to see the below answer. To help the community find the right answers, please do mark the post which was helpful by clicking on Accept Answer.

And, if you have any further questions do let us know.
Murarisetty Yamuna 140 Reputation points

2024-02-03T15:51:18.0133333+00:00

@GitaraniSharma-MSFT , As per the suggestions created the alert on compute unit whenever the instance count is reaching maximum instances of 125.Is there any recommendations to follow when we get this type of alert? What actions need to be taken on this?
Murarisetty Yamuna 140 Reputation points

2024-02-05T08:28:51.1433333+00:00

@GitaraniSharma-MSFT , Can you please look into the above question.
GitaraniSharma-MSFT 49,856 Reputation points Microsoft Employee

2024-02-05T13:53:17.6133333+00:00

@Murarisetty Yamuna , For Application Gateway v2 SKU, setting the maximum instance count to the maximum possible value of 125 allows the Application Gateway to scale out as needed. This allows it to handle the possible increase in traffic to your applications. And you've already set the maximum count to 125. So, it should be fine. Is your traffic constantly utilizing all the 125 instances?
Murarisetty Yamuna 140 Reputation points

2024-02-05T14:07:06.0833333+00:00

@GitaraniSharma-MSFT , Thank you for quick response. No the utilization of instances with in 125. So only to understand what action need to be taken when this alert (whenever the instance count is reaching maximum instances of 125.)received.
Murarisetty Yamuna 140 Reputation points

2024-02-05T14:11:17.29+00:00

@GitaraniSharma-MSFT , Thanks for quick response. No the utilization of instance is within 125. So only to understand what action need to taken when this alert(to monitor the instance count usage, Avg. Compute Unit utilization crossing 75%.) is received.
GitaraniSharma-MSFT 49,856 Reputation points Microsoft Employee

2024-02-05T14:30:45.1533333+00:00

@Murarisetty Yamuna , It's recommended that you set your minimum instance count to an optimal level. For example, if you require 50 instances to handle the traffic at peak load, then setting the minimum 25 to 30 is a good idea rather than at <10 so that even when there are short bursts of traffic, Application Gateway would be able to handle it and give enough time for autoscaling to respond and take effect.

You should check your Compute Unit metric for one month and based on your peak usage divided by 10, you can set the minimum number of instances required. If your Avg. Compute Unit utilization is always crossing 75% (i.e. 940 compute units or 94 instances), then you should set your minimum instance count around 70-80 to be able to handle the traffic bursts without any issues.

To understand how the pricing will be impacted with the change in instance count, please refer the below doc:

https://learn.microsoft.com/en-us/azure/application-gateway/understanding-pricing

Accepted answer

0 additional answers

Your answer

GitaraniSharma-MSFT 49,856 Reputation points Microsoft Employee

2024-01-25T14:31:02.37+00:00

@Murarisetty Yamuna , Just checking in to see if you had a chance to see the below answer. To help the community find the right answers, please do mark the post which was helpful by clicking on Accept Answer.

And, if you have any further questions do let us know.
Murarisetty Yamuna 140 Reputation points

2024-02-03T15:51:18.0133333+00:00

@GitaraniSharma-MSFT , As per the suggestions created the alert on compute unit whenever the instance count is reaching maximum instances of 125.Is there any recommendations to follow when we get this type of alert? What actions need to be taken on this?
Murarisetty Yamuna 140 Reputation points

2024-02-05T08:28:51.1433333+00:00

@GitaraniSharma-MSFT , Can you please look into the above question.
GitaraniSharma-MSFT 49,856 Reputation points Microsoft Employee

2024-02-05T13:53:17.6133333+00:00

@Murarisetty Yamuna , For Application Gateway v2 SKU, setting the maximum instance count to the maximum possible value of 125 allows the Application Gateway to scale out as needed. This allows it to handle the possible increase in traffic to your applications. And you've already set the maximum count to 125. So, it should be fine. Is your traffic constantly utilizing all the 125 instances?
Murarisetty Yamuna 140 Reputation points

2024-02-05T14:07:06.0833333+00:00

@GitaraniSharma-MSFT , Thank you for quick response. No the utilization of instances with in 125. So only to understand what action need to be taken when this alert (whenever the instance count is reaching maximum instances of 125.)received.
Murarisetty Yamuna 140 Reputation points

2024-02-05T14:11:17.29+00:00

@GitaraniSharma-MSFT , Thanks for quick response. No the utilization of instance is within 125. So only to understand what action need to taken when this alert(to monitor the instance count usage, Avg. Compute Unit utilization crossing 75%.) is received.
GitaraniSharma-MSFT 49,856 Reputation points Microsoft Employee

2024-02-05T14:30:45.1533333+00:00

@Murarisetty Yamuna , It's recommended that you set your minimum instance count to an optimal level. For example, if you require 50 instances to handle the traffic at peak load, then setting the minimum 25 to 30 is a good idea rather than at <10 so that even when there are short bursts of traffic, Application Gateway would be able to handle it and give enough time for autoscaling to respond and take effect.

You should check your Compute Unit metric for one month and based on your peak usage divided by 10, you can set the minimum number of instances required. If your Avg. Compute Unit utilization is always crossing 75% (i.e. 940 compute units or 94 instances), then you should set your minimum instance count around 70-80 to be able to handle the traffic bursts without any issues.

To understand how the pricing will be impacted with the change in instance count, please refer the below doc:

https://learn.microsoft.com/en-us/azure/application-gateway/understanding-pricing

Answer 1

Hello @Murarisetty Yamuna ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that you would like to setup an alert for your WAF v2 Application gateway, whenever the instance count is reaching maximum instances of 125.

To monitor instances approaching the maximum limit in application gateway, Is the metric signal "Current Capacity Unit " is the precise or not?

Capacity units represent overall gateway utilization in terms of throughput, compute, and connection count.

However, Compute unit's the measure of compute utilization of your Application Gateway.

Compute unit metric is a representation of your gateway's CPU utilization and based on your peak usage divided by 10, you can set the minimum number of instances required. Note that 1 application gateway instance can handle a minimum of 10 compute units.

So, the metric signal "Current Compute Unit" is more precise.

Refer: https://learn.microsoft.com/en-us/azure/application-gateway/high-traffic-support#set-your-minimum-instance-count-based-on-your-average-compute-unit-usage

Is creating an alert on the capacity units with a threshold value of 940 (75%) is the precise solution for continuously monitoring instances, ensuring awareness as they approach the maximum limit?

As mentioned above, to monitor the instance count usage, you should configure an alert for Avg. Compute Unit utilization crossing 75%.

https://learn.microsoft.com/en-us/azure/application-gateway/high-traffic-support#alerts-for-application-gateway-v2-sku-standard_v2waf_v2

If you want to know whenever the instance count is reaching maximum instances of 125, then you could setup an alert for Avg. Compute Unit utilization as below:

Maximum compute units are 1250(125*10).
75% of 1250 = 937.5 which could approx. to 940

User's image

Kindly let us know if the above helps or you need further assistance on this issue.

Please don’t forget to "Accept the answer" wherever the information provided helps you, this can be beneficial to other community members.

Share via

Need to know whenever the instance count is reaching maximum instances(125) in application gateway of waf v2 sku.

0 additional answers

Your answer