add image build

image/Dockerfile

@@ -0,0 +1,8 @@
+FROM ruby:2
+
+RUN apk --no-cache add build-base rpm tar zip
+RUN gem install --no-document fpm -v 1.11.0
+
+COPY entrypoint.sh /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]

image/entrypoint.sh

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+#!/usr/bin/env sh
+
+set -e
+
+FPMOPTS="${INPUT_FPM_OPTS}" fpm $@