Azure App Configuration
An Azure service that provides hosted, universal storage for Azure app configurations.
230 questions
Getting 502 Bad Gateway with Azure App Gateway with Web App as Backend
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Pallab Chakraborty
401
Reputation points
I am getting "502 Bad Gateway" after provisioning my Azure App Gateway. Let me explain the configuration for my infrastructure. We operate in a Landing Zone Environment where the spokes are routing traffic via the Hub
We have an Azure Firewall in the hub. We have multiple projects which are like individual landing zones sitting in individual subscriptions.
I have a similar setup in another landing zone where i have three backends : A Front End vue.js app, an API app and a Function App , all operating in one app service plan. All the Apps are VNET integrated and Private Endpoint enabled. I have created a route table with next hop as internet and attached it to the WAF subnet
I also have created three custom domains for the three apps and used well known CA certs and created TXT records and A records for them in our DNS server
So when i try to browse the friendly URL , it hits the App Gateway and i am able to browse the front end site absolutely fine.
But in this particular project, i have 5 web apps - One UI app and 4 API apps.
I have one app registration which is acting as the identity provider for the app. I have created similar kind of Route Table as i did for the other project and attached it to the WAF subnet. Here also, my apps are VNET integrated and Private Endpoint enabled
Right now , the code for my app is not deployed and it is an empty app service
So ideally , i should be getting the Microsoft page which says that your web app is running fine when i browse the UI app with its friendly URL
But instead i am getting 502 bad gateway.
So what can be the issue here ? I tried tunneling to the remote hub and tried accessing the UI app with its friendly URL bypassing the App Gateway, but still then i get 502 bad gateway. When i look at the overview page of the App Gateway via the Azure portal, it complains that the backend health is not right in a red banner
So i am not understanding what is the issue here, i have deleted and recreated the App Gateway, still the same.
{count} votes
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Vidya Narasimhan 2,126 Reputation points Microsoft Employee2022-07-04T20:08:01.543+00:00 Hi @Anonymous
Wanted to understand this statement from you better:**I tried tunneling to the remote hub and tried accessing the UI app with its friendly URL bypassing the App Gateway, but still then i get 502 bad gateway.*
Do you mean while trying to access the web app directly(bypassing app gateway) with a custom domain url that has been assigned to the web app (app service), you are getting 502 bad gateway error? If so, please try to resolve the web app error before troubleshooting app gateway.
Please review this link for possible causes of 502 error in app servicehttps://video2.skills-academy.com/en-us/azure/app-service/troubleshoot-http-502-http-503
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Wiliam Buzatto 1 Reputation point2022-07-05T14:52:48.803+00:00 Hi @Anonymous
As you describe, it looks like a problem with your WebApp.
Is your webapp responding correctly?Try accessing the Kudu console, the logs might be helpful: https://<Your app name>.scm.azurewebsites.net/
Please let me know if It is not the case.
Best, -
Pallab Chakraborty 401 Reputation points
2022-07-05T15:12:21.36+00:00 @Wiliam Buzatto If i login to our remote hub via tunnelling and try to access the web app with the URL https://*.azurewebsites.net, i get "The service is unavailable" message for this UI app. If i try to access using the custom domain, i get the 502 bad gateway. So any idea what does "Service is unavailable" means and why i get two messages with two URLs. The UI is the app which is exposed via App Gateway and it has a friendly URL with a Cert attached. So if i bypass the app gateway i get 502 bad gateway with the friendly URL and "service is unavailable" with the actual FQDN of the web app
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VenkateshDodda-MSFT 20,696 Reputation points Microsoft Employee2022-07-11T08:33:30.733+00:00 @Anonymous Apologize for the inconvenience that caused. Generally, you will see 503 errors (Service Unavailable) or 502 (bad gateway) occurs:
- request is taking longer time.
- application causing high memory/cpu
- application crashed due to an exception
You can follow these documentation steps and try to troubleshoot most common 502 & 503 errors in Azure App Service. For further investigations on this I will follow up with you privately.
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