Azure webapp node.js app not starting

Question

I'm trying to deploy a very simple express.js app on Azure webapp.

The deployment log shows the that the deployment passes correctly but the app doesn't start. Checking the kudu process explorer shows that indeed the node.js process is not running

On the other hand I don't see any application logs nor any indication that the app even started.

Is there a way to see what happened when the nodeiis tried to start the app?

Answer 1

Azure WebApp for node.js is running via iisnode as a native IIS module that allows hosting in IIS on Windows. Please see the document https://blogs.msdn.microsoft.com/silverlining/2012/06/14/windows-azure-websites-node-js/ to know its features.

For debugging the webapp for node.js, I suggest you can refer to the document to know how to do it.

If you are using Visual Studio as the IDE for node.js, I recommend installing NTVS in VS for debugging and deploying the node.js. Please see the documents below to know how to get started.

1. Installation for NTVS
2. Install Node.js and get started with NTVS

And there is an other tool called node-inspector for inspecting the node.js app on Azure. As reference, you can refer to the doc http://www.ranjithr.com/?p=98.

Meanwhile, please check the web.config file in your node webapp via Kudo Console, you can compare your codes with the sample generated by the template for Express from Gallery on Azure portal.

Hope it help. Any concern, please feel free to let me know.

---

The process explorer shows the processes of my webapp for node.js.

Answer 2

You need to enable logging before you can get logs that would (hopefully) give you more details about the error. You can read more about it here.

Answer 3

post my investigation step in here.
1. edit D:\home\site\wwwroot\iisnode.yml, from https://xxx.scm.azurewebsites.net/DebugConsole add below line

devErrorsEnabled: true  

2. restart app service from Azure portal
3. access your service, you will see something like this:

HRESULT: 0x2
HTTP status: 500
HTTP subStatus: 1002
HTTP reason: Internal Server Error

4. go to https://learn.microsoft.com/en-us/azure/app-service/app-service-web-nodejs-best-practices-and-troubleshoot-guide#iisnode-http-status-and-substatus to find the meanings for substatus.

for more debugging skill, you can see: https://prmadi.com/debug-nodejs-app-in-azure-app-services-windows-2/