add shellcheck and hadolint

.drone.yml

@@ -13,10 +13,19 @@ steps:
         exclude:
           - tag
 
-#  - name: hadolint
+  - name: shellcheck
-#    image: hadolint/hadolint:latest-debian
+    image: koalaman/shellcheck
-#    commands:
+    commands:
-#      - hadolint Dockerfile
+      - shellcheck app.sh
+    when:
+      event:
+        exclude:
+          - tag
+
+  - name: hadolint
+    image: hadolint/hadolint:latest-debian
+    commands:
+      - hadolint Dockerfile
 
 ---
 kind: pipeline