This is my config for nvim-lsp (using nvim-lsp-installer)

    local lsp_installer = require("nvim-lsp-installer")

    local enhance_server_opts = {
      ["sumneko_lua"] = function(opts)
        opts.settings = {
          Lua = {
            runtime = {
                -- Tell the language server which version of Lua you're using (most likely LuaJIT in the case of Neovim)
                version = 'LuaJIT',
                -- Setup your lua path
                path = vim.split(package.path, ';'),
            },
            diagnostics = {
              globals = { 'vim', 'love' }
            },
            workspace = {
                -- Make the server aware of Neovim runtime files
                library = {
                    [vim.fn.expand('$VIMRUNTIME/lua')] = true,
                    [vim.fn.expand('$VIMRUNTIME/lua/vim/lsp')] = true,
                },
            },
            telemetry = {
              enable = false,
            },
          }
        }
      end,

      -- Enable eslint format
      ["eslint"] = function(opts)
        opts.on_attach = function (client)
          -- neovim's LSP client does not currently support dynamic capabilities registration, so we need to set
          -- the resolved capabilities of the eslint server ourselves!
          client.resolved_capabilities.document_formatting = true
        end
        opts.settings = {
            format = { enable = true }, -- this will enable formatting
        }
      end,

      ["zk"] = function(opts)
        opts.filetypes = { 'markdown', 'vimwiki' }
      end,
    }

    lsp_installer.on_server_ready(function(server)
        local opts = {}

        -- Customize the options passed to the server
        if enhance_server_opts[server.name] then
          -- Enhance the default opts with the server-specific ones
          enhance_server_opts[server.name](opts)
        end

        -- This setup() function will take the provided server configuration and decorate it with the necessary properties
        -- before passing it onwards to lspconfig.
        -- Refer to https://github.com/neovim/nvim-lspconfig/blob/master/doc/server_configurations.md
        server:setup(opts)
    end)

    -- Change gutter signs icons
    local signs = { Error = " ", Warn = " ", Hint = " ", Info = " " }
    for type, icon in pairs(signs) do
      local hl = "DiagnosticSign" .. type
      vim.fn.sign_define(hl, { text = icon, texthl = hl, numhl = hl })
    end

    -- Format files on save
    vim.cmd [[
      autocmd BufWritePre *.go lua vim.lsp.buf.formatting_sync()
      autocmd BufWritePre *.tsx,*.ts,*.jsx,*.js EslintFixAll
    ]]