Are you facing an issue with your Azure Web App on Linux? Does your application crash when using the start script: “start”: “pm2 start server.js”? Are you seeing the error message “Container didn’t respond to HTTP pings on port: 8080”? If so, you’re in the right place. In this blog post, we’ll explore the possible causes and solutions for this problem, helping you get your Azure Web App up and running smoothly.
Understanding the Error
When you encounter the error “Container didn’t respond to HTTP pings on port: 8080,” it means that the container hosting your web app failed to respond to the HTTP pings on the specified port. This failure leads to the app not starting successfully, causing frustration and hindering your progress.
Investigating the Port Issue
One possible reason for this error is that port 8080 is not exposed in your container. By default, App Service expects your app to listen on port 80. To resolve this, you have a couple of options:
- Use the EXPOSE instruction in your Dockerfile to expose port 8080.
- Set the WEBSITES_PORT app setting to “8080” to expose the required port.
These options will ensure that the container can respond to the HTTP pings on the specified port, allowing your app to start successfully.
Checking Process Environment Variables
Another potential cause of the error is a mixup in the process environment variables. Specifically, if you’re using the “start”: “pm2 start server.js” script, there may be an issue with the process.env.PORT variable. This variable is used to set the port of your server, but it might be undefined when using the pm2 start script.
To address this, you can modify your code to include a fallback port. For example, you can use the following code snippet in your server.js file:
code
const port = process.env.PORT || 8080;
By setting a default port value, you ensure that your application has a valid port to listen on, even if the process environment variable is undefined. After making this change, redeploy your app to Azure, and it should start successfully.
Debugging Limitations
It’s important to note that once the container crashes, you might encounter difficulties debugging the issue. After the crash, you won’t be able to SSH into the container for inspection. Therefore, it’s crucial to address any potential issues proactively to avoid unnecessary downtime or frustration.
Additional Considerations
Here are a few additional points to keep in mind when troubleshooting this error:
- If you’re using a custom container, make sure your web app returns a “Not Found (404)” response for unimplemented API endpoints. This can help prevent unexpected issues and improve the overall stability of your app.
- If your application takes some time to respond, the default time limit for container startup is 230 seconds. If your app exceeds this limit, the container will halt and display the “container didn’t respond to HTTP pings” error. In such cases, you can increase the time limit by adjusting the WEBSITES_CONTAINER_START_TIME_LIMIT app setting in the Azure App Service configuration.
- Remember that App Service currently supports exposing only one port for HTTP requests. Make sure your app listens on the correct port and adjust the necessary settings to match.
Conclusion
In this blog post, we explored the error “Container didn’t respond to HTTP pings on port: 8080” when using the “start”: “pm2 start server.js” script in Azure Web App on Linux. We discussed the potential causes of this issue, including port exposure and process environment variables. Additionally, we provided solutions to address these problems, ensuring a successful startup of your web app.
By following the troubleshooting steps outlined here, you should be able to overcome the container crash and error message, allowing your application to run smoothly on Azure Web App. Remember to adapt the solutions to your specific scenario and configuration.
If you’re facing any further difficulties or have additional questions, don’t hesitate to consult the Microsoft Azure Collective or reach out to the Azure support team for assistance.