Azure web app restarts after modifying access restrictions - bug or a feature?

Rafał Duda 6

Hi,

I noticed that whenever I add a rule to access restrictions it restarts my web app. Today I added two rules (saving after each one) and experienced two restarts one after another. That hasn't been the case in the past and the corresponding documentation does not mention that this operation restarts the web app: https://learn.microsoft.com/pl-pl/azure/app-service/app-service-ip-restrictions

Web app restarted report confirms that the app has restarted stating User(Site Binding Change) as a reason, which does not seem related.

Best Regards,

Rafał

Ryan Hill 25,486 Reputation points Microsoft Employee

2020-08-06T01:57:38.48+00:00

@Rafał Duda apply access restrictions to your web app shouldn't trigger a web app restart. Can you attach your app service logs or provide your app name?
Rafał Duda 6 Reputation points

2020-08-06T07:42:30.813+00:00

Is there any way I can sent it via direct message? Activity log shows three "Update web sites config operations" at the exactly same time as restarts happened but nobody has updated app configuration at that time. According to explanation of User(Site Binding Change) reason on web app restarted report it may happen some time after swap, we made application swap about 12 hours before these restarts. It would be strange however that it occured in the very same moment I updated access restrictions and that it happened multiple times.
Ryan Hill 25,486 Reputation points Microsoft Employee

2020-08-06T13:45:35.01+00:00

@Rafał Duda sure, you can email me at AzCommunity[at]microsoft[dot]com ATTN Ryan.
Rafał Duda 6 Reputation points

2020-08-10T08:04:26.783+00:00
In the meantime I have sent a support request, I am posting the summary of response in case somebody else might investigate the same issue.
It turns out that:

application was restarted as site binding status changed, this site binding status may include the any change such as setting a restriction rule made to your entire App service.

change may trigger a restart without any action taken by the app owner

this usually happens when the underlying storage infrastructure of Azure App Service undergoes some changes. When that happens the application will restart on all VMs at the same time

Solution: Setting this app setting: WEBSITE_ADD_SITENAME_BINDINGS_IN_APPHOST_CONFIG to 1 (except if you are running WCF application)

I am yet to confirm if it really helps and if so I will put this information as an answer.
Neostarteon 1 Reputation point

2020-11-17T18:26:51.45+00:00

@Ryan Hill did you find the RCA for this?