Скачать или смотреть Fixing SassC::SyntaxError in Heroku After Upgrading Rails from 6.0 to 6.1

Learn how to resolve SassC::SyntaxError when deploying your Ruby on Rails app to Heroku after upgrading to version 6.1.
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This video is based on the question https://stackoverflow.com/q/67081163/ asked by the user 'karns' ( https://stackoverflow.com/u/3390279/ ) and on the answer https://stackoverflow.com/a/67099051/ provided by the user 'karns' ( https://stackoverflow.com/u/3390279/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting Deployment Failures on Heroku After Rails Upgrade

Upgrading your Ruby on Rails application can be an exciting but sometimes daunting task. While you might have everything working flawlessly in your local development environment, hitting deployment snags can be frustrating. In this guide, we will address a specific issue encountered when deploying to Heroku after upgrading Rails from 6.0 to 6.1. The error in question relates to SassC, a library used for compiling SCSS files, and the inability to find or read certain files during the asset precompile step.

The Problem

After upgrading from Rails version 6.0.3.4 to 6.1.3.1, you may have experienced the following error when running rails assets:precompile on Heroku:

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Breakdown of the Error

Where It Occurs: This error typically arises during the asset precompile step on Heroku.

What It Means: The SCSS file application.scss is trying to import the Bootstrap SCSS, but it can't find the necessary files, leading to a SyntaxError.

Local vs. Heroku Behavior: Interestingly, everything functions correctly in the development environment, which may lead developers to believe there’s a misconfiguration on Heroku.

Understanding the Root Cause

The primary reason for this failure hinges on how asset pipelines handle dependencies. When you run assets precompilation:

The asset pipeline first attempts to locate local files.

If those are not found, it will look into the node_modules folder, where many JavaScript packages (like Bootstrap) are typically installed when using Yarn.

In your specific case, it seems that the necessary node packages weren’t available in the node_modules directory at the time Heroku precompiled the assets.

The Solution: Adding the NodeJS Buildpack

To resolve this issue, the key step is to ensure that the NodeJS buildpack is correctly implemented in your Heroku setup. Follow these steps:

Step-by-Step Guide

Add the NodeJS Buildpack:

Run the following command in your terminal to add the NodeJS buildpack:

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This command ensures that the NodeJS buildpack runs before the Ruby buildpack.

Confirm Buildpack Order:

Check that the NodeJS buildpack appears above the Ruby buildpack in your buildpack list:

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Commit Your Changes:

Make sure to commit any changes if you have modified Gemfile, package.json, or other files related to asset management.

Redeploy Your Application:

After making these changes, trigger another deployment to Heroku:

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Watch for Successful Precompile:

Monitor the deployment logs to ensure that rails assets:precompile completes successfully without the previous errors.

Conclusion

By adding the NodeJS buildpack to your Heroku app, you can effectively resolve the SassC::SyntaxError encountered during deployment after upgrading to Rails 6.1. This change allows Heroku to install the necessary packages from your node_modules directory before it attempts to compile your assets, thus preventing the file-nonexistent errors.

With the right configuration, deploying your Rails applications can be a smoother process. Remember to stay updated on the dependencies and build environment settings, especially when performing major upgrades to your application.

If you encountered similar obstacles during your Rails upgrade, share your experiences in the comments below!