How can I fix a container that fails to start in Azure App Service?

Question

How can I fix a container that fails to start in Azure App Service?

Gawaskar 20

We are using NestJS for our back-end service, which has been running reliably for the past three years with the start command npm run start:qa and App Service Node version 20. I typically deploy the code using VS Code’s remote service, but the latest deployment failed. However, Azure logs now indicate a failure to start the application.

Log Stream

INFO  - Starting container for site

INFO  - docker run -d -p 4159:4203 --name mmac-qaapp_0_ff246e93 -e WEBSITE_USE_DIAGNOSTIC_SERVER=true -e PORT=4203 -e WEBSITE_SITE_NAME=mmac-qaapp -e WEBSITE_AUTH_ENABLED=False -e WEBSITE_ROLE_INSTANCE_ID=0 -e WEBSITE_HOSTNAME=mmac-qaapp.azurewebsites.net -e WEBSITE_INSTANCE_ID=4f7f9c220a4db25ee90a2ef6fa05bfd0a6bf89a64f74e6652d326553e672989c appsvc/node:20-lts_20240819.2.tuxprod REDACTED

INFO  - Logging is not enabled for this container.
Please use https://aka.ms/linux-diagnostics to enable logging to see container logs here.

INFO  - Initiating warmup request to container mmac-qaapp_0_ff246e93 for site mmac-qaapp

INFO  - Waiting for response to warmup request for container mmac-qaapp_0_ff246e93. Elapsed time = 16.9893417 sec

INFO  - Waiting for response to warmup request for container mmac-qaapp_0_ff246e93. Elapsed time = 36.1905157 sec

INFO  - Waiting for response to warmup request for container mmac-qaapp_0_ff246e93. Elapsed time = 55.7972945 sec

ERROR - Container mmac-qaapp_0_ff246e93 for site mmac-qaapp has exited, failing site start

ERROR - Container mmac-qaapp_0_ff246e93 didn't respond to HTTP pings on port: 4203, failing site start. See container logs for debugging.

INFO  - Stopping site mmac-qaapp because it failed during startup.

Can you provide a solution to resolve this issue?

RevelinoB 3,675 Reputation points

2024-11-03T21:01:34.61+00:00

Hi Gawaskar,

Your issue sounds familiar; I’ve seen similar cases with other users deploying Node applications to Azure App Services. When the container doesn’t respond to HTTP pings on the expected port, it’s usually related to the app’s binding configuration or recent updates in the environment.

Here’s what’s often helpful:

Port Binding: Make sure your application is listening on the exact port Azure specifies for the environment (PORT=4203). It’s best to confirm this in both your code and App Service settings.

Check Logs: Since Azure mentions logging isn’t enabled, you might want to turn it on. Doing so often reveals any underlying issues, like dependency conflicts or port misconfigurations.

Environment Variables: Double-check that all necessary environment variables are set correctly in your App Service. Missing or incorrect values here can prevent the container from starting up.

Review Recent Changes: If this issue started after recent code updates, it might help to revert to a known working version temporarily. This step can help isolate if a new dependency or change might be affecting the application.

Test Locally: Running the application in a Docker container locally, mimicking the Azure setup as closely as possible, can be a quick way to diagnose the issue.

Rebuild the Container: Sometimes, a clean rebuild and redeployment resolve issues caused by outdated or cached images, especially if there were recent updates to Node or other core dependencies.

Following these steps should help clarify whether the issue is due to the application configuration or the deployment environment. Let me know if you need more details on any of these steps!
VenkateshDodda-MSFT 24,951 Reputation points Microsoft Employee Moderator

2024-11-05T07:00:26.5133333+00:00

@Gawaskar Following up to see if you have a chance to check my previous response and helped, Do let me know if you have any further questions on this.

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Your answer

RevelinoB 3,675 Reputation points

2024-11-03T21:01:34.61+00:00

Hi Gawaskar,

Your issue sounds familiar; I’ve seen similar cases with other users deploying Node applications to Azure App Services. When the container doesn’t respond to HTTP pings on the expected port, it’s usually related to the app’s binding configuration or recent updates in the environment.

Here’s what’s often helpful:

Port Binding: Make sure your application is listening on the exact port Azure specifies for the environment (PORT=4203). It’s best to confirm this in both your code and App Service settings.

Check Logs: Since Azure mentions logging isn’t enabled, you might want to turn it on. Doing so often reveals any underlying issues, like dependency conflicts or port misconfigurations.

Environment Variables: Double-check that all necessary environment variables are set correctly in your App Service. Missing or incorrect values here can prevent the container from starting up.

Review Recent Changes: If this issue started after recent code updates, it might help to revert to a known working version temporarily. This step can help isolate if a new dependency or change might be affecting the application.

Test Locally: Running the application in a Docker container locally, mimicking the Azure setup as closely as possible, can be a quick way to diagnose the issue.

Rebuild the Container: Sometimes, a clean rebuild and redeployment resolve issues caused by outdated or cached images, especially if there were recent updates to Node or other core dependencies.

Following these steps should help clarify whether the issue is due to the application configuration or the deployment environment. Let me know if you need more details on any of these steps!
VenkateshDodda-MSFT 24,951 Reputation points Microsoft Employee Moderator

2024-11-05T07:00:26.5133333+00:00

@Gawaskar Following up to see if you have a chance to check my previous response and helped, Do let me know if you have any further questions on this.

Answer 1

VenkateshDodda-MSFT 24,951 Microsoft Employee Moderator

@Gawaskar Thanks for posting your question in Microsoft Q&A, apologize for any inconvenience caused on this.

As mentioned in the error message could you please enable diagnostic logging (application logs) in app service and review the container logs(using log stream) to troubleshoot this issue further.

You reference this techcommunity blog post to troubleshoot container issues on linux app service.

Hope this helps, let me know if you have any further questions on this.

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How can I fix a container that fails to start in Azure App Service?

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