Update Dockerfile

Replace with Alpine Linux based image

docker/Dockerfile

@@ -1,12 +1,10 @@
-FROM progrium/busybox
+FROM frolvlad/alpine-glibc:alpine-3.4
 
-RUN opkg-install curl
-RUN echo tlsv1 >> ~/.curlrc
-
-RUN curl -s -L https://github.com/chrislusf/seaweedfs/releases/latest | egrep -o '/chrislusf/seaweedfs/releases/download/.*/linux_amd64.tar.gz' | wget --base=http://github.com/ -i - && \
-  tar xzvf linux_amd64.tar.gz && \
-  mv weed /usr/bin/ && \
-  rm -r linux_amd64.tar.gz
+RUN apk add --no-cache --virtual=build-dependencies --update curl wget ca-certificates && \
+    wget -P /tmp https://github.com/$(curl -s -L https://github.com/chrislusf/seaweedfs/releases/latest | egrep -o '/chrislusf/seaweedfs/releases/download/.*/linux_amd64.tar.gz') && \
+    tar -C /usr/bin/ -xzvf /tmp/linux_amd64.tar.gz && \
+    apk del curl wget ca-certificates build-dependencies && \
+    rm -rf /tmp/*
 
 EXPOSE 8080
 EXPOSE 9333