add tini for handling zombie processes

Dockerfile

@@ -1,6 +1,6 @@
 FROM golang:alpine AS build
 
-RUN apk add --no-cache -U make git mercurial subversion bzr fossil
+RUN apk add --no-cache -U make git mercurial subversion
 
 COPY . /src/goproxy
 RUN cd /src/goproxy &&\
@@ -9,7 +9,12 @@ RUN cd /src/goproxy &&\
 
 FROM golang:alpine
 
-RUN apk add --no-cache -U git mercurial subversion bzr fossil
+# Add tini
+ENV TINI_VERSION v0.19.0
+ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini-static-amd64 /usr/bin/tini
+RUN chmod +x /usr/bin/tini
+
+RUN apk add --no-cache -U git mercurial subversion
 
 COPY --from=build /src/goproxy/bin/goproxy /goproxy
 
@@ -17,5 +22,5 @@ VOLUME /go
 
 EXPOSE 8081
 
-ENTRYPOINT ["/goproxy"]
+ENTRYPOINT ["/usr/bin/tini", "--", "/goproxy"]
 CMD []