jsonnet-lsp

This plugin aims to deliver a feature-rich, high quality, high performance IDE experience for Jsonnet. It is designed to work in large repositories with deeply nested imports.

Features

• Syntax Highliting and Basic Editing features
• Snippets
• Custom linting code that is able to deal with large codebases
  • The analysis code is optimized for real-time linting, and can return in <5ms when the normal linter could take minutes.
• Formatting
• Delta text update support for efficient editing
• Designed to remain performant in large repos with many files open
• Automatic detection of bazel-bin for generated files
• Type and Value Deduction
  • Supports imported files
  • Able to follow variables, function return values, and array/object indexing
• Autocomplete
  • Stdlib support with documentation and typed signatures
  • Scoped variable completion
  • Dotted autocomplete
  • Template object field completion
  • Import path completion for files
• Go to Definition
  • Can follow definitions in other files, including json files
• Hover Information
• Function Signature Help
• AST Recovery
  • The LSP is able recover common syntax issues while typing (like a missing semicolon) for a smoother experience

Missing Features

These are features I consider pretty important that are still missing:

• More type deduction logic and analysis
• More IDE options (options for linting, jpath, etc)
• First class multi-dimension jsonnet support

Development

• To develop the LSP, change the jsonnet.lsp.binaryPath setting to the runlsp.sh script in the root. Reloading the LSP in vscode (shift+cmd+p -> jsonnet: reload language server) will rebuild the server.
• To develop the client, open editor/code in vscode, and hit F5 to open a debug build of the client. Generally developing the LSP does not need a debug version of the client.

Release

• Github actions are setup to publish to OpenVSX automatically when a release is created
• The LSP binaries are bundled into the .vsix extension, to help reduce bugs from version skew and simplify installation.

Editor setup

Emacs

Emacs 29.1 has built in support for eglot and use-package. Assuming a functional package setup to download and install jsonnet-mode for Emacs. The below snippet will setup jsonnet-mode with jsonnet-lsp as language server using eglot.

(use-package jsonnet-mode
  :ensure t
  :config
  (add-to-list 'eglot-server-programs
               '(jsonnet-mode . ("jsonnet-lsp" "lsp")))
  :mode (
         ("\\.jsonnet\\'" . jsonnet-mode)
         ("\\.jsonnet.TEMPLATE\\'" . jsonnet-mode)
         )
  :hook
  (jsonnet-mode . (lambda()
                    (eglot-ensure))))

The above snippet assumes that jsonnet-lsp is installed into the PATH. Using the runlsp.sh script to dynamically build jsonnet-lsp on startup, a small update to the eglot-server-programs is needed.

  (add-to-list 'eglot-server-programs
               '(jsonnet-mode . ("/full/path/to/repo/jsonnet-lsp/runlsp.sh")))

Neovim

This recipe uses nvim-lspconfig to setup jsonnet-lsp with neovim. You will need to install the nvim-lspconfig plugin uses its instructions. Then, in you lua setup file (e.g. ~/.config/nvim/init.lua, see the official docs for setup) you can add:

local nvim_lsp = require('lspconfig')
nvm_lsp.jsonnet_ls.setup{
    cmd = { "/path/to/jsonnet-lsp/runlsp.sh" },
    filetypes = { "jsonnet", "libsonnet", ".jsonnet.template" },
    root_dir = nvm_lsp.util.root_pattern(".git", vim.fn.getcwd()),
    settings = {},
}