docker-service-discovery/openspec/changes/archive/2026-03-31-backend-url-env-var/tasks.md

1. Frontend Application Changes

• 1.1 In frontend/src/api.js, modify the logic to use process.env.REACT_APP_BACKEND_URL for the API base URL.
• 1.2 Implement a fallback to http://localhost:3001 in the same file for when the environment variable is not set.

2. Docker Configuration

• 2.1 In docker-compose.yml, update the frontend service definition to pass the REACT_APP_BACKEND_URL environment variable.
• 2.2 Add comments to docker-compose.yml to clarify the purpose and usage of the new environment variable.
• 2.3 In frontend/Dockerfile, add ARG and ENV to pass the REACT_APP_BACKEND_URL to the build process.

3. Documentation

• 3.1 Update the main README.md to document the new REACT_APP_BACKEND_URL environment variable, explaining its purpose and how to use it.