application gateway health probe issue

Question

application gateway health probe issue

Prasant Chettri 146

I keep getting health probe issue on application gateway with custom domain. I have listener with end to end encryption and same certificate as web app uploaded in the gateway.

I tried the gateway vnet with custom DNS and azure default DNs restarted app gateway on both cases and still same issue

I have NSG defined and UDR setup on application gateway sunbet.

Cannot connect to backend server. Check whether any NSG/UDR/Firewall is blocking access to the server. Check if application is running on correct port. To learn more visit - https://aka.ms/servernotreachable.

The test application with http listerner is passing the health probe

KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-16T04:47:40.7666667+00:00
@Prasant Chettri

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

Please note that the backend settings is different from Listener configuration.

You can have a

HTTP Listener with HTTPS Backend Settings and this would still work.

Similarly, having a HTTPS Listener with HTTP Backend Setting would work

as long as the configuration is correct.

Now, may I ask what exactly is the issue you are facing?

Is the configuration HTTPS Listener with HTTPS Backend Settings?

When you say "http listerner is passing the health probe",

do you mean the HTTP Listener is using a HTTP Backend Settings?

or the HTTP Listener is using a different HTTPS Backend Settings.

I believe you will be using End to End TLS (both Listener and Backend Settings would use HTTPS), but let me know if this is incorrect.

Is the custom domain added to the app service?

If not, make sure you follow the "Default domain" steps from Configure App Service with Application Gateway

If the above does not help, please share the configuration settings of your

working Listener and backend settings.

and non working Listener and backend settings.

Cheers,

Kapil
KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-20T11:36:01.5866667+00:00

@Prasant Chettri

May I know if you got a chance to review my previous comment?

Please let me know if you are facing any challenges or if there are any follow-up questions, I shall be glad to address them.

Thanks,

Kapil
KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-21T11:45:05.7066667+00:00

@Prasant Chettri

Can you please update us if the action plan provided was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.

Thanks,

Kapil
Prasant Chettri 146 Reputation points

2023-11-21T23:36:17.9033333+00:00

I was using https listener. I created single backend pool for two web app using same cert. I created two separate backend pool and backend setting which solved the issue
KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-22T10:06:53.35+00:00

@Prasant Chettri

Glad to know the issue has been resolved.

Thanks for keeping us updated.

Cheers,

Kapil

1 answer

Your answer

KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-16T04:47:40.7666667+00:00

@Prasant Chettri

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

Please note that the backend settings is different from Listener configuration.

You can have a

HTTP Listener with HTTPS Backend Settings and this would still work.

Similarly, having a HTTPS Listener with HTTP Backend Setting would work

as long as the configuration is correct.

Now, may I ask what exactly is the issue you are facing?

Is the configuration HTTPS Listener with HTTPS Backend Settings?

When you say "http listerner is passing the health probe",

do you mean the HTTP Listener is using a HTTP Backend Settings?

or the HTTP Listener is using a different HTTPS Backend Settings.

I believe you will be using End to End TLS (both Listener and Backend Settings would use HTTPS), but let me know if this is incorrect.

Is the custom domain added to the app service?

If not, make sure you follow the "Default domain" steps from Configure App Service with Application Gateway

If the above does not help, please share the configuration settings of your

working Listener and backend settings.

and non working Listener and backend settings.

Cheers,

Kapil
KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-20T11:36:01.5866667+00:00

@Prasant Chettri

May I know if you got a chance to review my previous comment?

Please let me know if you are facing any challenges or if there are any follow-up questions, I shall be glad to address them.

Thanks,

Kapil
KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-21T11:45:05.7066667+00:00

@Prasant Chettri

Can you please update us if the action plan provided was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.

Thanks,

Kapil
Prasant Chettri 146 Reputation points

2023-11-21T23:36:17.9033333+00:00

I was using https listener. I created single backend pool for two web app using same cert. I created two separate backend pool and backend setting which solved the issue
KapilAnanth-MSFT 49,611 Reputation points Microsoft Employee Moderator

2023-11-22T10:06:53.35+00:00

@Prasant Chettri

Glad to know the issue has been resolved.

Thanks for keeping us updated.

Cheers,

Kapil

Answer 1

@Prasant Chettri

I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this!

Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others", I'll repost your solution in case you'd like to "Accept" the answer.

Issue:

Configure Backend HTTP Settings for App gateway using multiple webApps

Solution:

You can have a

HTTP Listener with HTTPS Backend Settings and this would still work.
Similarly, having a HTTPS Listener with HTTP Backend Setting would work

as long as the configuration is correct.

You informed you were using https listener.
You created single backend pool for two web app using same certificate and created two separate backend pool and backend settings.
Adn confirmed this solved the issue If you have any other questions or are still running into more issues, please let me know.

Thank you again for your time and patience throughout this issue.

Cheers,

Kapil.

Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.

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application gateway health probe issue

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