Web app service becomes unavailable for a few hours

Question

Web app service becomes unavailable for a few hours

Ishai Dazhush 1

My web app service suddenly becomes unavailable for a few hours.
All the requests are pending for a few minutes and then fail. Restarting the app doesn't help. Stopping and starting again too.
Applications insights don't show those failed requests.
Please help, the app serves a lot of users and requests!

2 answers

Your answer

Answer 1

@Ishai Dazhush , Thanks for posting this question. Firstly, apologies for any inconvenience.

From the issue description, it looks like a quota issue.

Short Answer:
On App Service Free (or Shared) plan Quotas for Free or Shared apps are CPU, memory, bandwidth and filesystem.
When it exceeds you will receive quota error. You will have to wait until the quota resets or stop if there are unnecessary apps.

1.What App Service Plan are you leveraging?
2.On which region have provisioned your WebApp?
3. You have mentioned, ‘suddenly becomes unavailable for a few hours’, is this a newly deployed WebApp or have there been any recent changes?

Long Answer:

When you create a WebApp (/App) in App Service, it is put into an App Service plan. If there many Apps under the ASP, those share the same compute resources, and hit the limit. File system quota for App Service hosted apps is determined by the aggregate of App Service plans created in this region and resource group.

Review quotas and limits (from Azure Portal):

To review the status of the various quotas and metrics that affect an app:
In the Azure Portal, navigate to the WebApp setting> App Service Plan >> Quotas option.

Kindly check this document for more details on reviewing the Quota for App Service.

If one of the quotas has been reached, the usage bar will display in red instead of green. It will also tell you when the quota will be reset.

Recovery options if you reach a usage quota:

Wait until the quota is reset: Under each quota you will see “RESETS IN X HOURS X MINUTES”. This is the quota measurement period, and if you choose to wait, the site will not be functional until this expires.
-For example, the Data Out quota is applied per day. If the quota is reached in the first hour of the measurement period (one day), your site will be offline for 23 hours until the quota is reset.

Scale Up the Web Hosting Plan/Based on your requirement: Quotas only apply to the Free and Shared Web Hosting Plan modes. Depending on what quota you have reached.

ajkuma 28,036 Reputation points Microsoft Employee Moderator

2021-11-26T08:57:57.92+00:00

@Ishai Dazhush , Adding more info:

If you haven't done this already, you may leverage App Service diagnostics from Azure Portal> Navigate to your App Service app in the Azure Portal.
In the left navigation, click on Diagnose and solve problems and “Availability and Performance”. Go over the highlighted (screenshot below) options- to see if it provides additional pointers.

Ensure Always On is ON.

Always On is enabled on a site, Azure will automatically ping your WebApp regularly to ensure that the WebApp is always active and in a warm/running state.
This is useful to ensure that a site is always responsive (and that the app domain or worker process has not paged out due to lack of external HTTP requests).

You can change these settings in the configurations section of the Azure Portal (> on your Azure WebApp), under the General Settings tab:

Kindly let us know how it goes, I'll follow-up with you further.

Answer 2

Ishai Dazhush 1

Hey,

App Service Plan is Standard 2
Region is West Europe
No recent changes

I checked the quotas and limits:

![153105-image.png ]2

Everything is inside boundaries.

I have also generated an Availability and Performance report

Everything is good with an app, but all the requests are keep pending and eventually failing.

Please help ASAP, the app is in production.

ajkuma 28,036 Reputation points Microsoft Employee Moderator

2021-11-28T19:25:51.35+00:00

IshaiDazhush-0150, Thanks for the follow-up. Sorry you are still experiencing this issue. To investigate this further, I'll follow-up privately to get more information about your subscription and WebApp details.

In the interim, you may also review these config and features for further analysis:

Proactive Auto Heal, which automatically restarts your web app based on our percent memory and percent request rules.
Also, deployment pretty much does only one thing: it deploys files into the wwwroot folder. It never directly does anything to restart the App.
However, in some cases, the act of deploying files into wwwroot can cause some form of restart.

Checkout the Azure Service Health for any reported issues on your subscription.

Azure Service Health provides personalized alerts and guidance when Azure service issues affect you. It can notify you, help you understand the impact of issues, and keep you updated as the issue resolves.

Azure Resource Health helps you diagnose and get support for service problems that affect your Azure resources.

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Web app service becomes unavailable for a few hours

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