init.el

(use-package go-mode
  :ensure t
  :mode "\\.go\\'"
  :config
  (progn

    (defun gopath-set-here ()
      (interactive)
      (message (or (buffer-file-name) default-directory))
      (setenv "GOPATH"
              (f-expand (or (buffer-file-name) default-directory))))

    (setq gofmt-command (cond
                         ((executable-find "goimports") "goimports")
                         (t "gofmt")))

    (use-package go-stacktracer
      :ensure t
      :commands (go-stacktracer-region))

    (use-package go-eldoc
      :ensure t
      :init
      (progn
        (add-hook 'go-mode-hook 'go-eldoc-setup)))

    (use-package go-autocomplete
      :ensure t
      :pre-load
      (progn
        (use-package auto-complete :ensure t))
      :init
      (progn
        (add-hook 'go-mode-hook
                  #'(lambda ()
                      ;;; NOTE placing ac-source-yasnippet first is a work around.
                      ;; This is probably still an issue for modes where ac-source-yasnippet is
                      ;; not the last source.. (maybe) any source that has a prefix parser must
                      ;; be placed last until this issue is resolved.
                      ;; auto-complete/auto-complete#348 (comment)
                      (setq ac-sources
                            '(ac-source-yasnippet
                              ac-source-go))))))

    (bind-key "M-." 'godef-jump go-mode-map)))