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DevContainer CLI Workflow

Use your preferred editor (Vim, Emacs, Neovim, Claude Code, ...) with all OCaml tools running inside the container.

Prerequisites

Permission error? If npm install -g fails with EACCES, either configure npm's default directory or install with your system package manager (e.g. sudo apt install nodejs npm).

Podman alternative: On macOS, Podman works as a drop-in replacement for Docker Desktop. Install it via brew install podman, then create a docker alias so the DevContainer CLI finds it:

sudo ln -s $(which podman) /usr/local/bin/docker

See From Docker to Podman: VS Code DevContainers for details.

Quick start

git clone https://github.com/tarides/ocaml-devcontainer.git
cd ocaml-devcontainer
devcontainer up --workspace-folder .

# Run commands inside the container
devcontainer exec --workspace-folder . dune build

Using your editor

Run your editor inside the container where all OCaml tools are available:

devcontainer exec --workspace-folder . vim src/main.ml
devcontainer exec --workspace-folder . emacs src/main.ml
devcontainer exec --workspace-folder . nvim src/main.ml
devcontainer exec --workspace-folder . claude

Shell alias

Add to your shell config for convenience:

alias dc='devcontainer exec --workspace-folder .'

# Then:
dc dune build
dc vim src/main.ml

Using the TSan variant

For ThreadSanitizer support, use the TSan devcontainer configuration:

devcontainer up --workspace-folder . --config .devcontainer-tsan/devcontainer.json
devcontainer exec --workspace-folder . bash -c 'opam switch ocaml+tsan && eval $(opam env) && dune build'

See the README for details.

Stopping the container

docker stop $(docker ps -q --filter "label=devcontainer.local_folder=$(pwd)")

The workspace folder is mounted from your host, so your files are always safe on disk. State inside the container (installed packages, shell history) persists across docker stop/devcontainer up cycles as long as the container is not removed. Running docker rm or devcontainer up --remove-existing-container destroys that state.

Advanced editor integration

Emacs TRAMP

Edit files remotely using Emacs TRAMP with the Docker method.

  1. Start the container:

    devcontainer up --workspace-folder .

  2. Find the container name:

    docker ps --filter "label=devcontainer.local_folder=$(pwd)" --format '{{.Names}}'

  3. In Emacs, open files with:

    C-x C-f /docker:CONTAINER_NAME:/home/vscode/project/src/main.ml

  4. Configure eglot for LSP support — add to your Emacs config:

    (add-to-list 'eglot-server-programs
  '(tuareg-mode . ("docker" "exec" "-i" "CONTAINER_NAME" "ocamllsp")))

Neovim plugins

nvim-dev-container

For a VS Code-like "Reopen in Container" experience:

  1. Install nvim-dev-container
  2. Configure in your init.lua: 
    require('devcontainer').setup({})
  3. Use :DevcontainerStart to open in container

Manual LSP setup

vim.api.nvim_create_autocmd('FileType', {
  pattern = 'ocaml',
  callback = function()
    vim.lsp.start({
      name = 'ocamllsp',
      cmd = { 'docker', 'exec', '-i', 'CONTAINER_NAME', 'ocamllsp' },
      root_dir = vim.fs.dirname(vim.fs.find({'dune-project'}, {upward = true})[1]),
    })
  end,
})

Why this workflow?

  1. Works with any editor — no special plugins required
  2. Consistent environment — same tools, same versions, every time
  3. No host pollution — OCaml tools stay in the container
  4. Easy to teach — one pattern for all editors

See the README for installed tools, common commands, and switch details.