Resolving the EADDRINUSE Error with bolt-js Slack App Deployment on EC2 скачать в хорошем качестве

Resolving the EADDRINUSE Error with bolt-js Slack App Deployment on EC2

Discover how to fix the `EADDRINUSE` error that occurs while deploying a `bolt-js` Slack app using Jenkins and PM2 on AWS EC2. --- This video is based on the question https://stackoverflow.com/q/77094774/ asked by the user 'SEEWON' ( https://stackoverflow.com/u/19224978/ ) and on the answer https://stackoverflow.com/a/77742360/ provided by the user 'SEEWON' ( https://stackoverflow.com/u/19224978/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, comments, revision history etc. For example, the original title of the Question was: Bolt-js slack app Jenkins PM2 deployment EADDRINUSE issue Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- How to Fix the EADDRINUSE Error for Your bolt-js Slack App Deployment When deploying a Slack app built with bolt-js, you may encounter the notorious EADDRINUSE error while using Jenkins for CI/CD in conjunction with PM2 on AWS EC2. This issue often arises due to overlapping attempts to listen on the same network port by multiple instances of your application. In this guide, we'll break down the problem and provide a clear path to resolving it. Understanding the Problem You’ve set up a robust deployment pipeline, utilizing Jenkins and PM2, but when attempting to reload your application, you're met with an error indicating that port 3000 is already in use. Key Symptoms: Running pm2 start ecosystem.config.js works fine without errors. Running pm2 reload <appname> triggers an EADDRINUSE error. The app seems to stagger between different states of the cluster without fully transitioning. Unpacking the Deployment Setup Your configuration, as noted, uses pm2 in cluster mode. You have two cores in your EC2 instance, intended to run two instances of your application for load balancing and improved performance. The problematic section of your ecosystem.config.js might look something like this: [[See Video to Reveal this Text or Code Snippet]] The primary goal is to ensure that when you reload your app, PM2 can seamlessly transition between its instances without trying to bind to an already occupied port. Solution Overview The root of the problem lies in how the application's entry point is defined in your configuration. Here's what you need to change. Update the Entry Point Instead of running the application using npm start, which relies on the package.json script, specify the actual script file that should be executed. Your ecosystem.config.js should be modified from: [[See Video to Reveal this Text or Code Snippet]] to: [[See Video to Reveal this Text or Code Snippet]] Correct Configuration Example Here’s how your updated ecosystem.config.js should look: [[See Video to Reveal this Text or Code Snippet]] Why This Works By explicitly pointing to app.js, you're instructing PM2 to manage that specific file without relying on npm scripts that might not handle port allocations correctly. This change allows PM2 to appropriately bind your app to the specified port (3000), preventing the EADDRINUSE error stemming from multiple processes trying to listen simultaneously. Possible Workarounds While the above solution effectively resolves the issue, here are a few additional practices that may enhance your deployment process: Use Environment Variables: Consider using environment variables to dynamically assign ports based on your deployment environment. This can prevent port conflicts in varied environments. Health Checks: Implement health checks to ensure that old instances are fully terminated before new ones are brought up, thereby avoiding port conflicts on restarts or reloads. Graceful Shutdowns: Ensure your application handles SIGINT and SIGTERM signals to cleanly exit and release the port before new instances are initiated. Conclusion By adjusting the entry point in your ecosystem.config.js and explicitly defining the script, the EADDRINUSE issue can be effectively resolved. With this solution, your bolt-js Slack app should deploy seamlessly on AWS EC2, improving both reliability and performance. By following these guidelines, you'll be well on your way to deploying your Slack app without the frustrations of port conflicts. Happy coding!