Azure Web App Container Error

Question

Hi Everyone,

We have built one React application and are trying to deploy the same to Azure Web App.
The deployment was done using VS Code Azure Service plug in. The logs show deployment as a success however we are seeing the below error when trying to access the app via browser.

1. Waiting for response to warmup request for container
2. Container for site did not start within expected time limit. Elapsed time = 250.9032383 sec
3. Container didn't respond to HTTP pings on port: 8080, failing site start. See container logs for debugging.

Any help would be much appreciated.

Thanks
ThreeAtion

Answer 1

Thanks for asking question! If your site doesn't start suggest you check Docker log to troubleshoot it.

There are several ways to access Docker logs.

1. Docker logs appear on the Container Settings page in the portal. (These are truncated, but you can download them by clicking on the
   Download Logs button.)
2. You can find the Docker log in the /LogFiles directory. You can access this via the Kudu (Advanced Tools) Bash console or by using an
   FTP client to access it.
3. You can use our API to download the current logs. (See "You can discover and download the latest Docker logs using Kudu" in this
   post for info on that.) The naming convention for the Docker log is YYYY_MM_DD_RDxxxxxxxxxxxx_docker.log .

Further You may want to know that that your container must respond to an HTTP ping.

Could you please confirm if port : 8080 is exposed? as if it was never exposed the attempt to ping the container, we aren't pinging on a port on which the container is listening.

There are a couple of ways to resolve this.

Use the EXPOSE instruction in your Dockerfile to expose port 8080.

Use the WEBSITES_PORT app setting with a value of "8080" to expose that port.

Also, some container takes a long time to start means when we start your container, we'll wait a while for it to start and initialize. We consider the startup to be successful once the container is running and once we get a response to a ping so that we know it's ready to respond to HTTP traffic. We'll wait 230 seconds for that to happen. If we don't have a successful start within 230 seconds, we'll assume there's a problem and we'll stop the container.

You can resolve this by increasing that 230 second wait time up to a limit of 1800 seconds.

To configure that, add an app setting called WEBSITES_CONTAINER_START_TIME_LIMIT and set it to the number of seconds you would like for us to wait for your container to start (up to a maximum of 1800).

Check this detailed link on things you should know web app & linux :
https://techcommunity.microsoft.com/t5/apps-on-azure/things-you-should-know-web-apps-and-linux/ba-p/392472

Let us know if issue remains.

Answer 2

This can be due to so many reasons.

network restrictions or wrong port config. error on startup (caused by buggy code) slow compute (SKU of service plan) [most likely]

permission issues etc....

Diagnosing:

In my case i had to first look though the logs to ensure it is not a result of a mistake i made in my code.

Secondly looking through the docker logs (i was using a custom docker container - which was prebuilt by me).

Thirdly, looking through the diagnose and solve problems blade (tab) for potential issues/clues.

Solution:

WEBSITES_CONTAINER_START_TIME_LIMIT = 1800 in your app-settings (default is 120 which might not be enough)

Change the SKU of the service plan to a higher one in help increase the speed in startup/warmup. I recommend "D3" and above.

set WEBSITES_PORT = in your app-setting. (Note: it take precedence over PORT)

Set always_on = true