spacevim/bundle/nvim-lspconfig-latest/lua/lspconfig/server_configurations/gopls.lua

local util = require 'lspconfig.util'
local async = require 'lspconfig.async'
local mod_cache = nil

return {
  default_config = {
    cmd = { 'gopls' },
    filetypes = { 'go', 'gomod', 'gowork', 'gotmpl' },
    root_dir = function(fname)
      -- see: https://github.com/neovim/nvim-lspconfig/issues/804
      if not mod_cache then
        local result = async.run_command { 'go', 'env', 'GOMODCACHE' }
        if result and result[1] then
          mod_cache = vim.trim(result[1])
        end
      end
      if fname:sub(1, #mod_cache) == mod_cache then
        local clients = util.get_lsp_clients { name = 'gopls' }
        if #clients > 0 then
          return clients[#clients].config.root_dir
        end
      end
      return util.root_pattern('go.work', 'go.mod', '.git')(fname)
    end,
    single_file_support = true,
  },
  docs = {
    description = [[
https://github.com/golang/tools/tree/master/gopls

Google's lsp server for golang.
]],
    default_config = {
      root_dir = [[root_pattern("go.work", "go.mod", ".git")]],
    },
  },
}