Here is my .vimrc for Ack, But it can't search .go files, I'd like add .go support.
let g:ackprg="ack-grep -H --nocolor --nogroup --column"
function! Ack(args)
let grepprg_bak=&grepprg
exec "set grepprg=" . g:ackprg
execute "silent! grep " . a:args
botright copen
let &grepprg=grepprg_bak
exec "redraw!"
endfunction
command! -nargs=* -complete=file Ack call Ack(<q-args>)