diff --git a/.emacs.d/modes/99_docker.el b/.emacs.d/modes/99_docker.el
index f9f5ce7..3f00021 100644
--- a/.emacs.d/modes/99_docker.el
+++ b/.emacs.d/modes/99_docker.el
@@ -6,6 +6,7 @@
 
 (use-package dockerfile-mode
   :init
+  (add-to-list 'auto-mode-alist '("\\.[Dd]ockerfile\\'" . dockerfile-mode))
   )
 
 (use-package docker-compose-mode
diff --git a/.gitconfig b/.gitconfig
index 46db08a..c65fd06 100644
--- a/.gitconfig
+++ b/.gitconfig
@@ -60,3 +60,9 @@
     root = ~/.ghq/src
 
 # do `git config --local url.git@github.com:.insteadOf https://github.com/`
+[gpg]
+    format = ssh
+[user]
+    signingkey = ~/.ssh/id_ed25519.pub
+[commit]
+    gpgsign = true
\ No newline at end of file