ruby: add patch for 2.5 alpine version

see docker-library/ruby#196

ruby/2.5-alpine/Dockerfile

@@ -1,5 +1,117 @@
-FROM ruby:2.5-alpine3.7
+FROM alpine:3.7
 
+# 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 2.5
+ENV RUBY_VERSION 2.5.1
+ENV RUBY_DOWNLOAD_SHA256 886ac5eed41e3b5fc699be837b0087a6a5a3d10f464087560d2d21b3e71b754d
+ENV RUBYGEMS_VERSION 2.7.6
+ENV BUNDLER_VERSION 1.16.1
+
+# some of ruby's build scripts are written in ruby
+#   we purge system ruby later to make sure our final image uses what we just built
+# readline-dev vs libedit-dev: https://bugs.ruby-lang.org/issues/11869 and https://github.com/docker-library/ruby/issues/75
+RUN set -ex \
+	\
+	&& apk add --no-cache --virtual .ruby-builddeps \
+		autoconf \
+		bison \
+		bzip2 \
+		bzip2-dev \
+		ca-certificates \
+		coreutils \
+		dpkg-dev dpkg \
+		gcc \
+		gdbm-dev \
+		glib-dev \
+		libc-dev \
+		libffi-dev \
+		libressl \
+		libressl-dev \
+		libxml2-dev \
+		libxslt-dev \
+		linux-headers \
+		make \
+		ncurses-dev \
+		procps \
+		readline-dev \
+		ruby \
+		tar \
+		xz \
+		yaml-dev \
+		zlib-dev \
+	\
+	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
+	&& echo "$RUBY_DOWNLOAD_SHA256 *ruby.tar.xz" | sha256sum -c - \
+	\
+	&& mkdir -p /usr/src/ruby \
+	&& tar -xJf ruby.tar.xz -C /usr/src/ruby --strip-components=1 \
+	&& rm ruby.tar.xz \
+	\
+	&& cd /usr/src/ruby \
+  && wget -O - https://gist.githubusercontent.com/h3xby/4dc4928d92618de0e9c7edbc9e451a29/raw/2e87f5d2cd50d6786248f3151522e8ae2e98fe0c/ruby-2.5-alpine.patch | patch -p1 \
+	\
+# hack in "ENABLE_PATH_CHECK" disabling to suppress:
+#   warning: Insecure world writable dir
+	&& { \
+		echo '#define ENABLE_PATH_CHECK 0'; \
+		echo; \
+		cat file.c; \
+	} > file.c.new \
+	&& mv file.c.new file.c \
+	\
+	&& autoconf \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+# the configure script does not detect isnan/isinf as macros
+	&& export ac_cv_func_isnan=yes ac_cv_func_isinf=yes \
+	&& ./configure \
+		--build="$gnuArch" \
+		--disable-install-doc \
+		--enable-shared \
+	&& make -j "$(nproc)" \
+	&& make install \
+	\
+	&& runDeps="$( \
+		scanelf --needed --nobanner --format '%n#p' --recursive /usr/local \
+			| tr ',' '\n' \
+			| sort -u \
+			| awk 'system("[ -e /usr/local/lib/" $1 " ]") == 0 { next } { print "so:" $1 }' \
+	)" \
+	&& apk add --virtual .ruby-rundeps $runDeps \
+		bzip2 \
+		ca-certificates \
+		libffi-dev \
+		libressl-dev \
+		procps \
+		yaml-dev \
+		zlib-dev \
+	&& apk del .ruby-builddeps \
+	&& cd / \
+	&& rm -r /usr/src/ruby \
+	\
+	&& gem update --system "$RUBYGEMS_VERSION" \
+	&& gem install bundler --version "$BUNDLER_VERSION" --force \
+	&& rm -r /root/.gem/
+
+# install things globally, for great justice
+# and don't create ".bundle" in all our apps
+ENV GEM_HOME /usr/local/bundle
+ENV BUNDLE_PATH="$GEM_HOME" \
+	BUNDLE_BIN="$GEM_HOME/bin" \
+	BUNDLE_SILENCE_ROOT_WARNING=1 \
+	BUNDLE_APP_CONFIG="$GEM_HOME"
+ENV PATH $BUNDLE_BIN:$PATH
+RUN mkdir -p "$GEM_HOME" "$BUNDLE_BIN" \
+	&& chmod 777 "$GEM_HOME" "$BUNDLE_BIN"
+
+CMD [ "irb" ]
+
+# Custom stuff
 RUN apk add --no-cache curl wget bash git \
       tzdata coreutils build-base \
       nodejs yarn

ruby/update.sh

@@ -2,7 +2,7 @@
 # set -e
 
 versions=(
-  '2.2' 
+  '2.2'
   '2.3'
   '2.4'
   '2.5'
@@ -31,7 +31,7 @@ done
 
 versionsalpine37=(
   '2.4'
-  '2.5'
+  # '2.5'
 )
 
 for version in ${versionsalpine37[*]}; do