Hadolint LSP

A Language Server Protocol implementation for Hadolint, the Dockerfile linter.

Installation

npx @sankalpmukim/hadolint-lsp

Or install globally:

npm install -g @sankalpmukim/hadolint-lsp

OpenCode Integration

To use hadolint-lsp with OpenCode, add it to your opencode.json configuration file:

Local Configuration

Add to your project-local opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "lsp": {
    "hadolint": {
      "command": ["npx", "-y", "@sankalpmukim/hadolint-lsp", "--stdio"],
      "extensions": ["Dockerfile", "dockerfile"]
    }
  }
}

Global Configuration

Add to your global OpenCode config (usually at ~/.config/opencode/opencode.json):

{
  "$schema": "https://opencode.ai/config.json",
  "lsp": {
    "hadolint": {
      "command": ["npx", "-y", "@sankalpmukim/hadolint-lsp", "--stdio"],
      "extensions": ["Dockerfile", "dockerfile"]
    }
  }
}

If you have installed @sankalpmukim/hadolint-lsp globally, you can use:

{
  "$schema": "https://opencode.ai/config.json",
  "lsp": {
    "hadolint": {
      "command": ["hadolint-lsp", "--stdio"],
      "extensions": ["Dockerfile", "dockerfile"]
    }
  }
}

Notes

• The LSP server communicates via stdio, so the --stdio flag is important
• The extensions array specifies which file extensions the LSP should handle
• OpenCode will automatically start the LSP server when you open a Dockerfile
• Make sure hadolint is available in your PATH (see Requirements section)

Requirements

This LSP server requires hadolint to be installed and available in your PATH.

Install hadolint:

# On macOS
brew install hadolint

# On Linux
wget -O /usr/local/bin/hadolint https://github.com/hadolint/hadolint/releases/latest/download/hadolint-Linux-x86_64
chmod +x /usr/local/bin/hadolint

# Or using Docker (but LSP will not work with Docker)
docker pull hadolint/hadolint

Usage

Editor Integration

VS Code

Create or edit .vscode/settings.json:

{
  "dockerfile.languageserver": {
    "dockerfile-language-server-node": {
      "command": "@sankalpmukim/hadolint-lsp"
    }
  }
}

Or use with Docker extension that supports LSP.

Vim/Neovim

With nvim-lspconfig:

require'lspconfig'.hadolint_lsp.setup{
  cmd = { "@sankalpmukim/hadolint-lsp" },
  filetypes = { "dockerfile" },
  root_dir = require('lspconfig').util.root_pattern(".hadolint.yaml"),
}

Emacs

With lsp-mode:

(use-package lsp-mode
  :config
  (lsp-register-client
    (make-lsp-client :new-connection (lsp-stdio-connection "@sankalpmukim/hadolint-lsp")
                     :major-modes '(dockerfile-mode)
                     :server-id 'hadolint-lsp)))

Features

• Real-time Dockerfile linting
• Diagnostic highlighting
• Error, warning, info, and style level detection
• Supports all Hadolint rules
• Respects inline ignore pragmas (# hadolint ignore=DLxxxx)

Configuration

The LSP server respects Hadolint configuration files:

• .hadolint.yaml in the project root
• $XDG_CONFIG_HOME/hadolint.yaml
• $HOME/.config/hadolint.yaml
• $HOME/.hadolint.yaml

Example .hadolint.yaml:

failure-threshold: warning
ignored:
  - DL3008
override:
  error:
    - DL3006
  warning:
    - DL3015

Testing

Run the test suite:

npm test

The test suite covers:

• Hadolint integration
• Severity mapping
• Diagnostic generation
• Package structure validation
• Executable verification

All tests should pass (17 total tests as of v0.1.0).

Development

# Install dependencies
npm install

# Run tests
npm test

# Run in development mode
node src/index.js --stdio

License

GPL-3.0

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Related

• Hadolint - The Dockerfile linter
• Language Server Protocol