use alpine:latest (#1)

* use alpine:latest

* change entrypoint

* change script

* fix typo

Dockerfile

@@ -1,4 +1,3 @@
-FROM debian:stable-slim
-ADD entrypoint.sh /entrypoint.sh
-RUN chmod +x /entrypoint.sh
-ENTRYPOINT ["/entrypoint.sh"]
+FROM alpine:latest
+COPY entrypoint /usr/bin/entrypoint
+ENTRYPOINT ["entrypoint"]

entrypoint

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -e
+set -o pipefail
+
+sh -c "cp $*"

entrypoint.sh

@@ -1 +0,0 @@
-cp $SOURCE $TARGET