Use build args to pass node and gtt versions, and set default gtt version to 1.7.40

Author: juanluisbaptiste

Dockerfile

@@ -1,13 +1,14 @@
-FROM node:8.2.1-alpine
-
-ENV GTT_VERSION 1.7.39
+ARG NODE_VERSION=""
+FROM node:${NODE_VERSION:-8.2.1-alpine}
+ARG [email protected]
+ENV GTT_VERSION=$GTT_VERSION
 ENV EDITOR vi
 
 
 RUN apk update && \
     apk add git && \
     addgroup -S gtt && adduser -S gtt -G gtt && \
-    yarn global add --prefix /usr/local "gitlab-time-tracker@$GTT_VERSION"
+    yarn global add --prefix /usr/local "gitlab-time-tracker${GTT_VERSION}"
 USER gtt
 WORKDIR /home/gtt