Keystone – configure Dockerfiles and dev containers for any repo
We kept hitting the same wall: you clone some arbitrary repo and just want it to run without any configuration work. So we built Keystone, an open source tool that spins up a Modal sandbox, runs Claude Code inside it, and produces a working .devcontainer/ config (Dockerfile, devcontainer.json, test runner) for any git repo. We build on the dev container standard, so the output works with VS Code and GitHub Codespaces out of the box. Main use cases: reproducible dev/CI environments, self-describing repos, and safely sandboxed coding agents. Our goal is to encourage all repos to…
In plain words
Keystone is an open-source tool that automatically generates Docker and dev container configurations for any Git repository. It uses Claude Code running in a sandboxed Modal environment to analyze a repo and produce a working Dockerfile, devcontainer.json, and test runner compatible with VS Code and GitHub Codespaces. The tool is designed for developers who want reproducible development environments and self-describing repositories without manual configuration work.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
We kept hitting the same wall: you clone some arbitrary repo and just want it to run without any configuration work. So we built Keystone, an open source tool that spins up a Modal sandbox, runs Claude Code inside it, and produces a working .devcontainer/ config (Dockerfile, devcontainer.json, test runner) for any git repo. We build on the dev container standard, so the output works with VS Code and GitHub Codespaces out of the box. Main use cases: reproducible dev/CI environments, self-describing repos, and safely sandboxed coding agents. Our goal is to encourage all repos to self-describe their runtime environment. Why the sandbox? Running Claude directly against your Docker daemon is risky. We've watched it clear Docker config and tweak kernel settings when iterating on containers. Containerization matters most when your agent is acting like a sysadmin. To use it: get a Modal account and an Anthropic API key, run Keystone on your repo, check in the .devcontainer/ directory. See the project README for more details.
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