Overview
Docker is the container runtime that most self-hosted agent sandboxes are built on. A container packages code with its dependencies and runs it isolated from the host — so when you need a sandbox of your own rather than a managed service, a throwaway container is the usual building block.
flowchart LR code[LLM code] --> docker[Docker container] docker --> exec[(isolated process)] docker --> out[stdout / results]
It shares the host kernel, so isolation is medium — pair it with resource limits, a dropped-privilege user, and a blocked network for untrusted code. The engine is open (Apache-2.0); Docker Desktop and Hub add paid tiers for orgs.
When to use it
Reach for Docker when you want to run agent code on your own infrastructure instead of a hosted sandbox — local development, CI, or a self-managed runtime. It’s also what sits under the “Docker-out-of-Docker” pattern this very project uses to give agents a container to work in.