Configure lua language server for Neovim

There are two ways you can do this:

Project specific config

We can create a file called .luarc.json file in Neovim's config folder and add the following config.

{
  "runtime.version": "LuaJIT",
  "runtime.path": [
    "lua/?.lua",
    "lua/?/init.lua"
  ],
  "diagnostics.globals": ["vim"],
  "workspace.checkThirdParty": false,
  "workspace.library": [
    "$VIMRUNTIME",
    "./lua"
  ]
}

Fixed config

If your Neovim config is the only lua project you have in your system, use the function .nvim_lua_ls() to get the config and then setup lua_ls with lspconfig.

local lsp_zero = require('lsp-zero')

lsp_zero.on_attach(function(client, bufnr)
  -- see :help lsp-zero-keybindings
  -- to learn the available actions
  lsp_zero.default_keymaps({buffer = bufnr})
end)

local lua_opts = lsp_zero.nvim_lua_ls()
require('lspconfig').lua_ls.setup(lua_opts)

If you used mason-lspconfig.nvim to setup your language servers, add lua_ls to your handlers config.

local lsp_zero = require('lsp-zero')

lsp_zero.on_attach(function(client, bufnr)
  -- see :help lsp-zero-keybindings
  -- to learn the available actions
  lsp_zero.default_keymaps({buffer = bufnr})
end)

require('mason').setup({})
require('mason-lspconfig').setup({
  handlers = {
    function(server_name)
      require('lspconfig')[server_name].setup({})
    end,
    lua_ls = function()
      local lua_opts = lsp_zero.nvim_lua_ls()
      require('lspconfig').lua_ls.setup(lua_opts)
    end,
  },
})