Merge pull request linkedin#161 from ChristianKniep/sanitise_dockerfile

refine the Dockerfile slightly

Dockerfile

@@ -2,13 +2,18 @@ FROM golang:alpine
 
 MAINTAINER LinkedIn Burrow "https://github.com/linkedin/Burrow"
 
-RUN apk add --update bash curl git && apk add ca-certificates wget && update-ca-certificates && rm -rf /var/cache/apk/*
-
-RUN curl -sSO https://raw.githubusercontent.com/pote/gpm/v1.4.0/bin/gpm && \
-  chmod +x gpm && mv gpm /usr/local/bin
+RUN apk add --no-cache curl bash git ca-certificates wget \
+ && update-ca-certificates \
+ && curl -sSO https://raw.githubusercontent.com/pote/gpm/v1.4.0/bin/gpm \
+ && chmod +x gpm \
+ && mv gpm /usr/local/bin
 
 ADD . $GOPATH/src/github.com/linkedin/Burrow
-RUN cd $GOPATH/src/github.com/linkedin/Burrow && gpm install && go install && mv $GOPATH/bin/Burrow $GOPATH/bin/burrow
+RUN cd $GOPATH/src/github.com/linkedin/Burrow \
+ && gpm install \
+ && go install \
+ && mv $GOPATH/bin/Burrow $GOPATH/bin/burrow \
+ && apk del git curl wget
 
 ADD docker-config /etc/burrow