Slim down dockerfile

Author: nicosuave

Dockerfile

@@ -1,21 +1,18 @@
-FROM java
+FROM openjdk:alpine
 
 LABEL maintainer "Jeff Sippel <[email protected]>"
 
-RUN apt-get update
-RUN apt-get install -y ruby ruby-nokogiri
-
-RUN adduser -u 9000 --disabled-password --quiet --gecos "" app
-USER app
-
-WORKDIR /usr/src/app
+RUN apk update && \
+  apk upgrade && \
+  apk add --no-cache ruby ruby-nokogiri ruby-json
 
 COPY scalastyle_config.xml /usr/src/app/
 COPY scalastyle_2.11-0.6.0-batch.jar /usr/src/app/
 
 COPY . /usr/src/app
 
+WORKDIR /usr/src/app
+
 VOLUME /code
-WORKDIR /code
 
-CMD ["/usr/src/app/bin/scalastyle"]
+CMD ./bin/scalastyle