haskell-devcontainer

A ready-to-use Docker image for Haskell development, built on top of the VS Code Dev Containers base image. Pull it, attach VS Code, and get a fully configured Haskell environment in seconds — no local toolchain required.

Quick Start

// .devcontainer/devcontainer.json
{
  "image": "ivelten/haskell-devcontainer:latest",
  "remoteUser": "vscode",
  "postCreateCommand": "npm install -g @anthropic-ai/claude-code",
  // Drop all Linux capabilities not needed for Haskell development.
  // Do NOT add privileged:true or mount /var/run/docker.sock — doing so
  // grants the container (and any AI assistant running inside it) full
  // control over the Docker daemon on your host.
  "runArgs": [
    "--cap-drop=ALL",
    "--security-opt=no-new-privileges:true",
    "--pids-limit=2048"
  ]
}

What's Inside

Haskell Toolchain

Tool	Version
GHC	9.10.3
Cabal	3.12.1.0
Stack	latest
GHCup	latest

Developer Tools

• HLS — Haskell Language Server for IDE features (completions, type hints, go-to-definition)
• Hoogle — Local Haskell API search database, pre-generated at build time
• Ormolu — Opinionated, deterministic code formatter
• fast-tags — Fast tag file generator for Haskell source
• cabal-gild — Formatter and linter for .cabal files
• direnv — Per-directory environment variable loading, hooked into both bash and zsh
• Node.js & npm — Available for general development and for installing npm-based tools via postCreateCommand

Debugging (DAP)

Full Debug Adapter Protocol support via:

• haskell-dap
• ghci-dap
• haskell-debug-adapter

Platform Support

Images are built for both linux/amd64 (Intel/AMD) and linux/arm64 (Apple Silicon).

CI/CD

The image is automatically built and published to Docker Hub on every version tag (v*.*.*) and on manual workflow dispatch, via GitHub Actions. Versioned tags follow semver: pushing v1.2.3 publishes :1.2.3, :1.2, :1, and :latest.

Before publishing, the CI pipeline runs two Trivy gates:

1. Dockerfile misconfiguration scan — fails on CRITICAL/HIGH misconfigurations
2. Image vulnerability scan — builds the amd64 image first, scans it with Trivy, uploads the SARIF report to the GitHub Security tab, and blocks the multi-platform push if any fixable CRITICAL/HIGH CVEs are found

Security

The image is designed to run without host privileges. The runArgs in the Quick Start snippet enforce this:

Flag	What it prevents
--cap-drop=ALL	Removes all Linux capabilities (filesystem ownership changes, raw sockets, kernel module loading, etc.)
--security-opt=no-new-privileges:true	Prevents any process inside the container from gaining elevated privileges via setuid/setgid binaries
--pids-limit=2048	Limits the number of processes to prevent fork bombs; high enough for parallel GHC compilation

Never add "privileged": true or mount /var/run/docker.sock into the container. Either grants any process running inside (including AI coding assistants) full control over the Docker daemon on your host machine — a trivial container escape.

Supply-chain hardening

direnv is compiled from source inside a golang:1.26.3-bookworm builder stage rather than downloaded as a prebuilt binary. Prebuilt binaries bundle the Go stdlib version used at release time and cannot be updated independently; building from source ensures the embedded stdlib is the patched version.

Notes

• Cabal jobs are set to $ncpus for parallel builds.
• Documentation generation is disabled in Cabal to speed up package installs.
• The image runs as the non-root vscode user, as expected by the Dev Containers spec.