Add null-ls and register as LSP formatter

config/nvim/lua/config_plugins/config_lsp.lua

@@ -1,3 +1,17 @@
+-- Set up null_ls first
+local null_ls = require("null-ls")
+null_ls.setup {
+    sources = {
+        null_ls.builtins.code_actions.gitsigns,
+        null_ls.builtins.diagnostics.mypy,
+        null_ls.builtins.formatting.black,
+        null_ls.builtins.formatting.isort,
+        null_ls.builtins.formatting.latexindent,
+        null_ls.builtins.formatting.trim_whitespace,
+        null_ls.builtins.hover.dictionary,
+    },
+}
+
 -- Mappings.
 -- See `:help vim.diagnostic.*` for documentation on any of the below functions
 local opts = { noremap = true, silent = true }
@@ -12,6 +26,17 @@ for type, icon in pairs(signs) do
     vim.fn.sign_define(hl, { text = icon, texthl = hl, numhl = hl })
 end
 
+local lsp_formatting = function (bufnr)
+    vim.lsp.buf.format({
+        filter = function (client)
+            return client.name == "null-ls"
+        end,
+        bufnr = bufnr,
+        timeout_ms = 2000,
+        -- async = true,
+    })
+end
+
 -- Use an on_attach function to only map the following keys
 -- after the language server attaches to the current buffer
 local on_attach = function(client, bufnr)
@@ -34,9 +59,7 @@ local on_attach = function(client, bufnr)
     vim.keymap.set('n', '<leader>D', vim.lsp.buf.type_definition, bufopts)
     vim.keymap.set('n', '<leader>rn', vim.lsp.buf.rename, bufopts)
     vim.keymap.set('n', '<leader>ca', vim.lsp.buf.code_action, bufopts)
-    vim.keymap.set('n', '<leader>i', function()
-        vim.lsp.buf.format({ timeout_ms = 10000, async = false })
-    end, bufopts)
+    vim.keymap.set('n', '<leader>i', lsp_formatting, bufopts)
 end
 
 local lsp_flags = {

config/nvim/lua/plugins.lua

@@ -41,6 +41,7 @@ require('packer').startup {
             'saadparwaiz1/cmp_luasnip',
             'rafamadriz/friendly-snippets',
             'windwp/nvim-autopairs',
+            'https://github.com/jose-elias-alvarez/null-ls.nvim',
         }
         use {
             'nvim-treesitter/nvim-treesitter',