Adjust the order we do things a bit to enable non-root usage trivially

Dockerfile-alpine.template

@@ -1,14 +1,20 @@
 FROM alpine:3.3
 
+# skip installing gem documentation
+RUN mkdir -p /usr/local/etc \
+	&& { \
+		echo 'install: --no-document'; \
+		echo 'update: --no-document'; \
+	} >> /usr/local/etc/gemrc
+
 ENV RUBY_MAJOR %%VERSION%%
 ENV RUBY_VERSION %%FULL_VERSION%%
 ENV RUBY_DOWNLOAD_SHA256 %%SHA256%%
 ENV RUBYGEMS_VERSION %%RUBYGEMS%%
 
-# skip installing gem documentation
+# some of ruby's build scripts are written in ruby
-RUN echo -e 'install: --no-document\nupdate: --no-document' >> "$HOME/.gemrc"
+# we purge this later to make sure our final image uses what we just built
-
+RUN set -ex \
-RUN set -x \
 	&& apk add --no-cache --virtual .ruby-builddeps \
 		autoconf \
 		bison \
@@ -40,12 +46,13 @@ RUN set -x \
 	&& mv "/usr/src/ruby-$RUBY_VERSION" /usr/src/ruby \
 	&& rm ruby.tar.gz \
 	&& cd /usr/src/ruby \
+	&& { echo '#define ENABLE_PATH_CHECK 0'; echo; cat file.c; } > file.c.new && mv file.c.new file.c \
 	&& autoconf \
 	# the configure script does not detect isnan/isinf as macros
-	&& ac_cv_func_isnan=yes ac_cv_func_isinf=yes ./configure --disable-install-doc \
+	&& ac_cv_func_isnan=yes ac_cv_func_isinf=yes \
+		./configure --disable-install-doc \
 	&& make -j"$(nproc)" \
 	&& make install \
-	&& gem update --system $RUBYGEMS_VERSION \
 	&& runDeps="$( \
 		scanelf --needed --nobanner --recursive /usr/local \
 			| awk '{ gsub(/,/, "\nso:", $2); print "so:" $2 }' \
@@ -63,17 +70,21 @@ RUN set -x \
 		procps \
 		zlib-dev \
 	&& apk del .ruby-builddeps \
+	&& gem update --system $RUBYGEMS_VERSION \
 	&& rm -r /usr/src/ruby
 
-# install things globally, for great justice
-ENV GEM_HOME /usr/local/bundle
-ENV PATH $GEM_HOME/bin:$PATH
-
 ENV BUNDLER_VERSION %%BUNDLER%%
 
 RUN gem install bundler --version "$BUNDLER_VERSION" \
 	&& bundle config --global path "$GEM_HOME" \
-	&& bundle config --global bin "$GEM_HOME/bin"
+	&& bundle config --global bin "$GEM_HOME/bin" \
+	&& bundle config --global silence_root_warning true
+
+# install things globally, for great justice
+ENV GEM_HOME /usr/local/bundle
+ENV PATH $GEM_HOME/bin:$PATH
+RUN mkdir -p "$GEM_HOME" \
+	&& chmod 777 "$GEM_HOME"
 
 # don't create ".bundle" in all our apps
 ENV BUNDLE_APP_CONFIG $GEM_HOME

Dockerfile-slim.template

@@ -13,17 +13,22 @@ RUN apt-get update \
 		zlib1g-dev \
 	&& rm -rf /var/lib/apt/lists/*
 
+# skip installing gem documentation
+RUN mkdir -p /usr/local/etc \
+	&& { \
+		echo 'install: --no-document'; \
+		echo 'update: --no-document'; \
+	} >> /usr/local/etc/gemrc
+
 ENV RUBY_MAJOR %%VERSION%%
 ENV RUBY_VERSION %%FULL_VERSION%%
 ENV RUBY_DOWNLOAD_SHA256 %%SHA256%%
 ENV RUBYGEMS_VERSION %%RUBYGEMS%%
 
-# skip installing gem documentation
-RUN echo 'install: --no-document\nupdate: --no-document' >> "$HOME/.gemrc"
-
 # some of ruby's build scripts are written in ruby
 # we purge this later to make sure our final image uses what we just built
-RUN buildDeps=' \
+RUN set -ex \
+	&& buildDeps=' \
 		autoconf \
 		bison \
 		gcc \
@@ -37,27 +42,23 @@ RUN buildDeps=' \
 		make \
 		ruby \
 	' \
-	&& set -x \
 	&& apt-get update \
 	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
-	&& mkdir -p /usr/src/ruby \
 	&& curl -fSL -o ruby.tar.gz "http://cache.ruby-lang.org/pub/ruby/$RUBY_MAJOR/ruby-$RUBY_VERSION.tar.gz" \
 	&& echo "$RUBY_DOWNLOAD_SHA256 *ruby.tar.gz" | sha256sum -c - \
+	&& mkdir -p /usr/src/ruby \
 	&& tar -xzf ruby.tar.gz -C /usr/src/ruby --strip-components=1 \
 	&& rm ruby.tar.gz \
 	&& cd /usr/src/ruby \
+	&& { echo '#define ENABLE_PATH_CHECK 0'; echo; cat file.c; } > file.c.new && mv file.c.new file.c \
 	&& autoconf \
 	&& ./configure --disable-install-doc \
 	&& make -j"$(nproc)" \
 	&& make install \
+	&& apt-get purge -y --auto-remove $buildDeps \
 	&& gem update --system $RUBYGEMS_VERSION \
-	&& rm -r /usr/src/ruby \
+	&& rm -r /usr/src/ruby
-	&& apt-get purge -y --auto-remove $buildDeps
-
-# install things globally, for great justice
-ENV GEM_HOME /usr/local/bundle
-ENV PATH $GEM_HOME/bin:$PATH
 
 ENV BUNDLER_VERSION %%BUNDLER%%
 
@@ -66,6 +67,12 @@ RUN gem install bundler --version "$BUNDLER_VERSION" \
 	&& bundle config --global bin "$GEM_HOME/bin" \
 	&& bundle config --global silence_root_warning true
 
+# install things globally, for great justice
+ENV GEM_HOME /usr/local/bundle
+ENV PATH $GEM_HOME/bin:$PATH
+RUN mkdir -p "$GEM_HOME" \
+	&& chmod 777 "$GEM_HOME"
+
 # don't create ".bundle" in all our apps
 ENV BUNDLE_APP_CONFIG $GEM_HOME
 

Dockerfile.template

@@ -1,36 +1,43 @@
 FROM buildpack-deps:jessie
 
+# skip installing gem documentation
+RUN mkdir -p /usr/local/etc \
+	&& { \
+		echo 'install: --no-document'; \
+		echo 'update: --no-document'; \
+	} >> /usr/local/etc/gemrc
+
 ENV RUBY_MAJOR %%VERSION%%
 ENV RUBY_VERSION %%FULL_VERSION%%
 ENV RUBY_DOWNLOAD_SHA256 %%SHA256%%
 ENV RUBYGEMS_VERSION %%RUBYGEMS%%
 
-# skip installing gem documentation
-RUN echo 'install: --no-document\nupdate: --no-document' >> "$HOME/.gemrc"
-
 # some of ruby's build scripts are written in ruby
 # we purge this later to make sure our final image uses what we just built
-RUN apt-get update \
+RUN set -ex \
-	&& apt-get install -y bison libgdbm-dev ruby \
+	&& buildDeps=' \
+		bison \
+		libgdbm-dev \
+		ruby \
+	' \
+	&& apt-get update \
+	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
-	&& mkdir -p /usr/src/ruby \
 	&& curl -fSL -o ruby.tar.gz "http://cache.ruby-lang.org/pub/ruby/$RUBY_MAJOR/ruby-$RUBY_VERSION.tar.gz" \
 	&& echo "$RUBY_DOWNLOAD_SHA256 *ruby.tar.gz" | sha256sum -c - \
+	&& mkdir -p /usr/src/ruby \
 	&& tar -xzf ruby.tar.gz -C /usr/src/ruby --strip-components=1 \
 	&& rm ruby.tar.gz \
 	&& cd /usr/src/ruby \
+	&& { echo '#define ENABLE_PATH_CHECK 0'; echo; cat file.c; } > file.c.new && mv file.c.new file.c \
 	&& autoconf \
 	&& ./configure --disable-install-doc \
 	&& make -j"$(nproc)" \
 	&& make install \
-	&& apt-get purge -y --auto-remove bison libgdbm-dev ruby \
+	&& apt-get purge -y --auto-remove $buildDeps \
 	&& gem update --system $RUBYGEMS_VERSION \
 	&& rm -r /usr/src/ruby
 
-# install things globally, for great justice
-ENV GEM_HOME /usr/local/bundle
-ENV PATH $GEM_HOME/bin:$PATH
-
 ENV BUNDLER_VERSION %%BUNDLER%%
 
 RUN gem install bundler --version "$BUNDLER_VERSION" \
@@ -38,6 +45,12 @@ RUN gem install bundler --version "$BUNDLER_VERSION" \
 	&& bundle config --global bin "$GEM_HOME/bin" \
 	&& bundle config --global silence_root_warning true
 
+# install things globally, for great justice
+ENV GEM_HOME /usr/local/bundle
+ENV PATH $GEM_HOME/bin:$PATH
+RUN mkdir -p "$GEM_HOME" \
+	&& chmod 777 "$GEM_HOME"
+
 # don't create ".bundle" in all our apps
 ENV BUNDLE_APP_CONFIG $GEM_HOME