How to stop specific nodes in Azure App Gateway

Question

How to stop specific nodes in Azure App Gateway

Mahesh Aralelemath 71

Hi,

We have few servers behind the Azure App Gateway. We wanted to take out specific nodes while updating the patches or app package till the time testing is completed.

Is there any option to mark specific node as maintenance? so that App Gateway wont be sending any traffic to these nodes till these nodes maintenance switch is turned off?

I know the health probe monitoring but that is good when service is down but here the ask is to stop the node participating in backend pool while it is in patching and testing stage.

Appreciate any thoughts on this.

Regards

Mahesh

KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-19T06:41:58.1333333+00:00
@Mahesh Aralelemath

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

I understand that you are looking for a solution to "disable" a backend pool member.

Currently, we do not have a feature that would do this implicitly.

As stated by Sedat SALMAN , you can consider Connection draining and run the powershell command Set-AzApplicationGatewayBackendAddressPool

First, get the BackendAddressPool via Get-AzApplicationGatewayBackendAddressPool

Update this to remove the node that has a planned maintenance

And then Set-ting the backendPool.

You may request this feature in the forum : Azure Feedback hub.

All the feedback shared in these forums are monitored and reviewed by the Microsoft engineering teams responsible for building Azure

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

Thanks,

Kapil

Please don’t forget to close the thread by clicking "Accept the answer" wherever the information provided helps you, as this can be beneficial to other community members.
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-19T10:31:32.8+00:00
@Mahesh Aralelemath

Adding to this,

You can consider using a custom Probe with Probe matching condition.

You should use "HTTP response status code match"

Generally, A HTTP response has with status code between 200 and 399 is considered healthy

You can configure this and define what HTTP response code should the App gateway consider healthy

When the backend is in a "Updating" state, the backend should send a HTTP Response code , which would make the App gateway consider this backend as unhealthy.

So, App gateway will stop forwarding the traffic to this backend

Once the update is done, the backend should start sending back a valid HTTP response and then App gateway will consider this healthy again, and start sending traffic.

P.S :

This still requires that the Application code is configured to send a custom HTTP response when it is updating/patching.

Complete platform support is not available

Hope this helps

Cheers,

Kapil
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-20T06:12:21.7633333+00:00

@Mahesh Aralelemath

Reaching out to check if there are any questions on this.

Please let us know if we can be of any further assistance here.

Thanks,

Kapil
Mahesh Aralelemath 71 Reputation points

2023-10-20T06:16:07.0533333+00:00

Hi Kapil, I have raised it as feedback, we can close this thread.

Thanks
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-20T06:21:11.0033333+00:00

@Mahesh Aralelemath

You are welcome.

I have summarized my comments and posted it as a new answer.

I would highly appreciate if you could Accept the answer and close this thread.

Original posters help the community find answers faster by identifying the correct answer.

Thanks for your continued contribution on Q&A and appreciate much for taking the time to share your feedback.

Thanks,

Kapil
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-23T05:43:38.3233333+00:00

@Mahesh Aralelemath

Greetings.

Request you please consider "Accepting the answer" and closing this thread, which might be beneficial to other community members to arrive at the correct question/answer easily.

Cheers,

Kapil

Accepted answer

1 additional answer

Your answer

KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-19T06:41:58.1333333+00:00

@Mahesh Aralelemath

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

I understand that you are looking for a solution to "disable" a backend pool member.

Currently, we do not have a feature that would do this implicitly.

As stated by Sedat SALMAN , you can consider Connection draining and run the powershell command Set-AzApplicationGatewayBackendAddressPool

First, get the BackendAddressPool via Get-AzApplicationGatewayBackendAddressPool

Update this to remove the node that has a planned maintenance

And then Set-ting the backendPool.

You may request this feature in the forum : Azure Feedback hub.

All the feedback shared in these forums are monitored and reviewed by the Microsoft engineering teams responsible for building Azure

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

Thanks,

Kapil

Please don’t forget to close the thread by clicking "Accept the answer" wherever the information provided helps you, as this can be beneficial to other community members.
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-19T10:31:32.8+00:00

@Mahesh Aralelemath

Adding to this,

You can consider using a custom Probe with Probe matching condition.

You should use "HTTP response status code match"

Generally, A HTTP response has with status code between 200 and 399 is considered healthy

You can configure this and define what HTTP response code should the App gateway consider healthy

When the backend is in a "Updating" state, the backend should send a HTTP Response code , which would make the App gateway consider this backend as unhealthy.

So, App gateway will stop forwarding the traffic to this backend

Once the update is done, the backend should start sending back a valid HTTP response and then App gateway will consider this healthy again, and start sending traffic.

P.S :

This still requires that the Application code is configured to send a custom HTTP response when it is updating/patching.

Complete platform support is not available

Hope this helps

Cheers,

Kapil
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-20T06:12:21.7633333+00:00

@Mahesh Aralelemath

Reaching out to check if there are any questions on this.

Please let us know if we can be of any further assistance here.

Thanks,

Kapil
Mahesh Aralelemath 71 Reputation points

2023-10-20T06:16:07.0533333+00:00

Hi Kapil, I have raised it as feedback, we can close this thread.

Thanks
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-20T06:21:11.0033333+00:00

@Mahesh Aralelemath

You are welcome.

I have summarized my comments and posted it as a new answer.

I would highly appreciate if you could Accept the answer and close this thread.

Original posters help the community find answers faster by identifying the correct answer.

Thanks for your continued contribution on Q&A and appreciate much for taking the time to share your feedback.

Thanks,

Kapil
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-23T05:43:38.3233333+00:00

@Mahesh Aralelemath

Greetings.

Request you please consider "Accepting the answer" and closing this thread, which might be beneficial to other community members to arrive at the correct question/answer easily.

Cheers,

Kapil

Answer 1

KapilAnanth-MSFT 49,536 Microsoft Employee Moderator

@Mahesh Aralelemath

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

I understand that you are looking for a solution to "disable" a backend pool member.

Currently, we do not have a feature that would do this implicitly.

As stated by Sedat SALMAN , you can consider Connection draining and run the powershell command Set-AzApplicationGatewayBackendAddressPool

First, get the BackendAddressPool via Get-AzApplicationGatewayBackendAddressPool
Update this to remove the node that has a planned maintenance
And then Set-ting the backendPool.

I suggested you may request this feature in the forum : Azure Feedback hub.

You informed us you have created one and we can archive this thread.

Thanks,

Kapil

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

Mahesh Aralelemath 71 Reputation points

2023-10-19T09:53:10.92+00:00

Thanks for the details Kapil
KapilAnanth-MSFT 49,536 Reputation points Microsoft Employee Moderator

2023-10-25T12:06:13.3633333+00:00

@Mahesh Aralelemath

You are most welcome.

Cheers,

Kapil

Answer 2

Sedat SALMAN 14,180 MVP

Connection draining helps you achieve graceful removal of backend pool members during planned service updates or problems with backend health. This setting is enabled via the Backend Setting and is applied to all backend pool members during rule creation.

You can check the following link: https://learn.microsoft.com/en-us/azure/application-gateway/features

or

A more direct way to temporarily stop nodes is to manually remove them from the backend pool using the Remove-AzApplicationGatewayBackendAddressPool command. This will prevent the Application Gateway from sending any traffic to these nodes until they are re-added to the backend pool

Mahesh Aralelemath 71 Reputation points

2023-10-19T09:57:37.7466667+00:00

Hi Salman,

Removing node from back end pool is crude way of doing and its not feasible option in operations.

There should be more better way to manage this so that people can access the Web/App individually before joining back to Back End Pool.

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How to stop specific nodes in Azure App Gateway

1 additional answer

Your answer