Ask, in one call, whether your Python process is running inside Docker

When it’s useful

Logging, configuration, and feature flags sometimes need to branch on “are we in a container?” Re-implementing cgroup and filesystem probes is tedious and easy to get subtly wrong. This package concentrates that logic behind a single, cache-friendly function, useful in CI images, local compose stacks, and servers where Docker is the runtime.

What you can do

• Call is_docker() for a boolean answer based on multiple detection paths (as implemented in the library), not a single brittle check.
• Reuse cached results by default for speed, and force a fresh probe when the environment may have changed mid-process.
• Ship with zero third-party dependencies beyond the standard library expectations of the package itself.

Limits and fit

Detection answers “Docker-style container” as implemented; unusual sandboxes, partial mounts, or future runtime changes can still surprise any heuristic. If you need proof of a specific orchestrator, combine this with your platform’s own signals. Python 3.8+; install from PyPI (docker-detector). Usage and changelog are in the GitHub repository (conceptually aligned with the is-docker npm utility this project draws from).