Fix React Hot Reload Not Working in Docker: A Simple Watchpack Environment Variable Solution

Introduction

If you’ve been struggling with getting React hot reload to work inside a Docker container, you’re not alone. This common issue can be frustrating, but there’s a straightforward fix involving a specific environment variable in watchpack. In this post, I’ll walk you through the problem, the solution, and how you can implement it to keep your development flow smooth and efficient.

What is React Hot Reload?

React hot reload allows you to instantly see changes in your React application without refreshing the entire app. This feature significantly speeds up the development process, making it easier to tweak your UI and see immediate results.

The Problem with Docker

Running a React application inside Docker can complicate hot reload due to file system differences between the host and the Docker container. This discrepancy often causes watchpack, the library responsible for monitoring file changes, to miss updates, leading to the dreaded issue of hot reload not working.

The Solution: Watchpack Environment Variable

The key to solving this problem lies in adjusting a specific environment variable in watchpack. By setting this variable, you can ensure that watchpack correctly detects file changes, enabling React’s hot reload feature to function as expected.

Step-by-Step Guide

1. Update Your Dockerfile

First, ensure your Dockerfile is set up to handle environment variables correctly. Add the following line to your docker-compose.yml file:

This sets an environment variable that instructs watchpack to use polling, which is more reliable in a Docker environment.

1. Rebuild Your Docker Container

After making these changes, rebuild your Docker container to apply the new settings:

docker-compose up --build

Conclusion

By adding a simple environment variable to watchpack and tweaking your webpack configuration, you can fix the React hot reload issue inside Docker. This solution ensures that your development workflow remains seamless and efficient, allowing you to focus on building great applications.

Additional Tips

•Ensure your Docker volumes are correctly configured to sync files between your host and container.

•Regularly update your Docker images and dependencies to benefit from the latest fixes and improvements.

Call to Action

If you found this guide helpful, don’t forget to clap and share it with fellow developers. Have any other tips or solutions for working with React and Docker? Drop a comment below!

I hope this helps! Let me know if there’s anything else you’d like to add or modify.

Comments

[Ralph de Ruijter]

Thx for the tip.

One small thing the environment variable must be writen with a :

environment:
      WATCHPACK_POLLING: true