Docker

Docker packages applications and their dependencies into containers — standardized units that share the host operating system's kernel instead of virtualizing an entire OS. This makes containers start in milliseconds and use a fraction of the resources a traditional virtual machine requires. On macOS and Windows, Docker Desktop runs a lightweight Linux VM transparently; on Linux, containers run natively. Images are defined in a Dockerfile as a series of reproducible, independently cached layers.

The Docker Hub registry provides official images for most databases, runtimes, and tools. Docker Compose defines multi-container environments in a single YAML file, making it straightforward to run databases, message brokers, and application services together during development. In production, containers are typically orchestrated by platforms like Kubernetes rather than managed by Docker alone.

Docker images conform to the OCI specification, ensuring portability across any compliant container runtime. Docker Engine is at version 29, which switched to the containerd image store as the default for new installations. The documentation is comprehensive and actively maintained.

Podman (Apache 2.0) is a daemonless, rootless container engine that serves as a drop-in replacement for Docker's CLI. Unlike Docker, Podman does not require a central background daemon — each container runs as a direct child process of the invoking user. This architecture improves security by enabling rootless containers by default and simplifies integration with systemd. Podman supports Docker Compose files, OCI images, and can even alias docker commands transparently, making migration straightforward.