SSH-config Language Server (sshls)

A Language Server for OpenSSH configuration files, with a CLI formatter.

✨ Features

• Formatting of SSH config files via the sshls format command
• Language server started with sshls server, following the Language Server Protocol (LSP)
• Formatting, real-time error reporting and keyword completion through the language server

📦 Installation

You can install the tool easily with pipx or uv:

uv tool install ssh-config-ls

🧑‍💻 Editor integration

While the formatter can be used from the terminal, the main feature of sshls is its server. Since it is compliant with the LSP, it can be more or less easily used with your favorite editor.

Neovim 0.11+

If sshls is available on your path, you can use the vim.lua framework to configure the server, in <rtp>/lsp/sshls.lua:

return {
    cmd = { "sshls", "server" },
    filetypes = { "sshconfig" },
    settings = {}, -- Put your options there
}

Just do not forget to enable the config:

vim.lsp.enable("sshls")

🔧 Configuration

The language server accepts the following options from the client (e.g. Neovim):

{
    formatter = {
        indent = "    ",  -- Indentation for directives inside Host and Match blocks
        separator = " ",  -- Separator between a keyword and its arguments
        sort_directives = true, -- Sort directives within blocks
    }
}

🚧 Roadmap

This is the Python prototype of the language server. The following features are currently planned to reach a mature state and a stable API, but additional features may be added as development progresses:

• Implement a lexer
  • Keep comments for easier formatting
• Implement a parser
  • Parse directives blocks (the global one and Host and Match ones)
• Implement a formatter
  • Remove blocks without directives
  • Indent Host and Match blocks
  • Sort directives within a block
  • Sort consecutive Host blocks
• Provide a CLI
  • Add the format subcommand to format a file
  • format: add a --check option to give a status code
  • format: add a --diff option to show the difference between the current file and the formatted replacement
  • Add the server subcommand to start the language server over STDIO
• Language server
  • textDocument/formatting
  • textDocument/completion
  • textDocument/diagnostic - Report syntax errors
  • textDocument/diagnostic - Report warnings
  • textDocument/hover
• Test coverage

Once all features have been implemented and the program has reached a mature stage, I will release version 1.0 and start working on the Rust rewrite. Of course, I will continue to fix bugs, but new features will not necessarily be added to the Python implementation in the meantime (and since learning Rust is the main reason I started this project, it will take time).

For the Rust implementation, it is planned to use the tower-lsp crate instead of the pygls Python module.

References

• The Rust Book
• Rustlings
• tower-lsp