nvim lspconfig

Install nvim-lspconfig according to the instructions in its README.

https://github.com/neovim/nvim-lspconfig/blob/master/lua/lspconfig/ccls.lua has a built-in rule for ccls. You can customize initialization options with:

local lspconfig = require'lspconfig'
lspconfig.ccls.setup {
  init_options = {
    cache = {
      directory = ".ccls-cache";
    };
  }
}