Description

Proposal

Add a .devcontainer/ folder to provide optional support for GitHub Codespaces and Visual Studio Code's DevContainer feature.

This would allow new contributors to get a ready-to-use Symfony development environment instantly, without manually configuring PHP, required extensions (like ext-xsl), or Composer.

What's included

• A minimal Dockerfile based on php:8.3-alpine
• Composer preinstalled globally
• Required PHP extensions like xsl (used in core)
• A non-root user (devuser) for good container practices
• Workspace mapped to /workspaces/symfony
• Recommended VS Code extensions (PHP, Xdebug, etc.)

Why

Symfony has a large and growing contributor base, but setting up a full local environment remains a barrier, especially for new contributors or those exploring the codebase.

Providing an optional, zero-config, fully reproducible container environment helps:

• Lower the entry barrier for contributions
• Encourage contributions via GitHub Codespaces
• Ensure environment consistency during PR testing/debugging

Impact

This is completely optional. It has:

• No impact on the Symfony runtime
• No change to the test pipeline
• No dependency on external services

It only adds a .devcontainer/ folder at the root, which is ignored by Symfony’s autoloading, tests, and builds.

Preview

I’ve implemented a working version in a dedicated branch here (not submitted as a PR yet, pending approval):

🔗 https://github.com/mathieucorne/symfony/tree/feature/devcontainer-support
📁 https://github.com/mathieucorne/symfony/tree/feature/devcontainer-support/.devcontainer

Let me know if this is something you'd be interested in — I’ll gladly open a PR if approved.