So, with these steps, you should be able to resolve the 502 Bad Gateway error when deploying a Node.js application on Elastic Beanstalk. Each of these steps addresses the most common causes of the problem, from incorrect configurations to version conflicts.
Problems with Babel and dependencies in the cloud
When deploying Node.js applications to Elastic Beanstalk, a recurring issue that can arise is key dependencies disappearing after each deployment, especially Babel-related dependencies. This was the case with the @babel/plugin-proposal-class-properties plugin , which disappeared or was not available after deployment to the production environment, despite working perfectly on the local environment.
Babel is a crucial tool for transpiling modern JavaScript code denmark mobile numbers list into a version that is compatible with more environments. However, during deployments to Elastic Beanstalk, issues often occur such as dependencies that are correctly installed in the local environment going missing. In our case, @babel/plugin-proposal-class-properties was disappearing on every deployment, causing compilation errors during the build phase.
This issue was caused by the Elastic Beanstalk environment not properly handling development dependencies (devDependencies) and treating them as optional or removing them during production. While this worked fine on-premises, in the cloud, certain configurations in the project files and tools involved were causing Babel to not have access to the required plugins, such as @babel/plugin-proposal-class-properties.
How to ensure that Babel and its plugins are correctly configured in the production environment
To ensure that Babel dependencies are properly maintained in the Elastic Beanstalk environment, several solutions were implemented:
Include Babel dependencies in the correct section of `package.json`
One practice that can prevent dependencies from disappearing is to ensure that Babel's essential dependencies are properly listed in the package.json file. While build tools are usually placed in devDependencies so that they are only installed in development environments, in our case it was necessary to move some of them to dependencies so that they would always be available in the production environment.
"dependencies": {
"@babel/core": "^7.13.16",
"@babel/cli": "^7.13.16",
"@babel/plugin-proposal-class-properties": "^7.18. 6",
"@babel/preset-env": "^7.25.8",
...
}
This ensures that when Elastic Beanstalk installs the dependencies, it does not skip these essential tools, allowing the build process to work correctly in the production environment. In your case, you will most likely only need to add the build tools in devDependencies.
Review the . npmrc file
The .npmrc file can affect how dependencies are installed in Elastic Beanstalk. In our case, we had the engine-strict=true option , which forced npm to use a specific version of Node.js, causing conflicts with Babel versions.
To fix this issue, we either removed the .npmrc file or adjusted its settings. Specifically, we made sure that the unsafe-perm=true option was enabled to allow dependencies to be installed with proper permissions in environments where root access is not available: