Containerizing and Testing a Python Backtesting System With Docker and GitHub Actions

Not long ago, I broke a backtest without changing a single line of code. I moved the script to a different machine—same OS, supposedly the same Python version — and the equity curve suddenly told a completely different story.

Nothing in the logic had changed. The environment was the only obvious difference. That was the day I stopped treating the runtime environment as an afterthought and started treating reproducibility as part of the experiment itself.