diff --git a/32-emulator/Dockerfile b/32-emulator/Dockerfile
index 9a83206..f018598 100644
--- a/32-emulator/Dockerfile
+++ b/32-emulator/Dockerfile
@@ -100,20 +100,14 @@ RUN adb keygen ~/.android/adbkey
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/32-jdk17/Dockerfile b/32-jdk17/Dockerfile
index fecb2b8..ed6a8a1 100644
--- a/32-jdk17/Dockerfile
+++ b/32-jdk17/Dockerfile
@@ -79,20 +79,14 @@ RUN sdkmanager --verbose "platform-tools" "platforms;android-$ANDROID_PLATFORM_V
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/32-ndk/Dockerfile b/32-ndk/Dockerfile
index 0f7dae6..145a04a 100644
--- a/32-ndk/Dockerfile
+++ b/32-ndk/Dockerfile
@@ -85,20 +85,14 @@ RUN sdkmanager --verbose $ANDROID_NDK_PACKAGES
 ##</ndk>##
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/32-stf-client/Dockerfile b/32-stf-client/Dockerfile
index 5d40bf3..dbf6cbf 100644
--- a/32-stf-client/Dockerfile
+++ b/32-stf-client/Dockerfile
@@ -98,20 +98,14 @@ RUN adb keygen ~/.android/adbkey
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/32/Dockerfile b/32/Dockerfile
index f46d428..b712bf6 100644
--- a/32/Dockerfile
+++ b/32/Dockerfile
@@ -79,20 +79,14 @@ RUN sdkmanager --verbose "platform-tools" "platforms;android-$ANDROID_PLATFORM_V
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/33-emulator/Dockerfile b/33-emulator/Dockerfile
index 4bf5635..8773128 100644
--- a/33-emulator/Dockerfile
+++ b/33-emulator/Dockerfile
@@ -100,20 +100,14 @@ RUN adb keygen ~/.android/adbkey
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/33-jdk17/Dockerfile b/33-jdk17/Dockerfile
index 131b87f..ba3b97a 100644
--- a/33-jdk17/Dockerfile
+++ b/33-jdk17/Dockerfile
@@ -79,20 +79,14 @@ RUN sdkmanager --verbose "platform-tools" "platforms;android-$ANDROID_PLATFORM_V
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/33-ndk/Dockerfile b/33-ndk/Dockerfile
index a943cd7..d43f791 100644
--- a/33-ndk/Dockerfile
+++ b/33-ndk/Dockerfile
@@ -85,20 +85,14 @@ RUN sdkmanager --verbose $ANDROID_NDK_PACKAGES
 ##</ndk>##
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/33-stf-client/Dockerfile b/33-stf-client/Dockerfile
index 4ae5123..382c817 100644
--- a/33-stf-client/Dockerfile
+++ b/33-stf-client/Dockerfile
@@ -98,20 +98,14 @@ RUN adb keygen ~/.android/adbkey
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/33/Dockerfile b/33/Dockerfile
index b2e89c5..a09e39b 100644
--- a/33/Dockerfile
+++ b/33/Dockerfile
@@ -79,20 +79,14 @@ RUN sdkmanager --verbose "platform-tools" "platforms;android-$ANDROID_PLATFORM_V
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/34-emulator/Dockerfile b/34-emulator/Dockerfile
index 176b02e..8a9465a 100644
--- a/34-emulator/Dockerfile
+++ b/34-emulator/Dockerfile
@@ -100,20 +100,14 @@ RUN adb keygen ~/.android/adbkey
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/34-jdk11/Dockerfile b/34-jdk11/Dockerfile
index b6f1b65..03d9841 100644
--- a/34-jdk11/Dockerfile
+++ b/34-jdk11/Dockerfile
@@ -79,20 +79,14 @@ RUN sdkmanager --verbose "platform-tools" "platforms;android-$ANDROID_PLATFORM_V
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/34-ndk/Dockerfile b/34-ndk/Dockerfile
index 7684a42..01a6315 100644
--- a/34-ndk/Dockerfile
+++ b/34-ndk/Dockerfile
@@ -85,20 +85,14 @@ RUN sdkmanager --verbose $ANDROID_NDK_PACKAGES
 ##</ndk>##
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/34-stf-client/Dockerfile b/34-stf-client/Dockerfile
index 91742d7..c389758 100644
--- a/34-stf-client/Dockerfile
+++ b/34-stf-client/Dockerfile
@@ -98,20 +98,14 @@ RUN adb keygen ~/.android/adbkey
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/34/Dockerfile b/34/Dockerfile
index 961f4a6..16b1c66 100644
--- a/34/Dockerfile
+++ b/34/Dockerfile
@@ -79,20 +79,14 @@ RUN sdkmanager --verbose "platform-tools" "platforms;android-$ANDROID_PLATFORM_V
 
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/Dockerfile.template b/Dockerfile.template
index 948bae4..f9c85f2 100644
--- a/Dockerfile.template
+++ b/Dockerfile.template
@@ -125,20 +125,14 @@ RUN sdkmanager --verbose $ANDROID_NDK_PACKAGES
 ##</ndk>##
 
 ##<ruby-bundler>##
+# hadolint ignore=DL3008
 RUN apt-get update \
-&& apt-get -y --no-install-recommends install imagemagick=8:6.9.10.23+dfsg-2.1ubuntu11 \
-&& rm -rf /var/lib/apt/lists/* \
-&& curl -k -0L https://github.com/postmodern/ruby-install/archive/master.tar.gz -o ruby-install.tar.gz \
-&& tar -xzvf ruby-install.tar.gz
-WORKDIR /ruby-install-master
-RUN apt-get update && apt-get -y --no-install-recommends install make=4.2.1-1.2 \
-&& rm -rf /var/lib/apt/lists/* \
-&& make install
-WORKDIR /
-RUN apt-get update \
-&& rm -rf ruby-install-master && rm -rf ruby-install.tar.gz \
-&& ruby-install --latest \
-&& ruby-install -i /usr/local/ ruby 2.6.8 -- --disable-install-doc \
-&& gem update --system --no-document \
-&& gem install bundler:1.17.3 --force
+  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends gnupg2 \
+  && rm -rf /var/lib/apt/lists/* \
+  && gpg2 --keyserver keyserver.ubuntu.com --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
+  && curl -sSL https://get.rvm.io | bash -s stable --ruby --without-gems="rvm rubygems-bundler" \
+  && echo "source /etc/profile.d/rvm.sh" >> /etc/bash.bashrc \
+  && source /usr/local/rvm/scripts/rvm \
+  && gem install bundler:1.17.3 --force --no-document
+SHELL [ "/bin/bash", "-l", "-c" ]
 ##</ruby-bundler>##
diff --git a/README.md b/README.md
index 752c3c9..4f3b3c7 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,11 @@ An image that lets us build android apps with docker using gitlab-ci
 
 ## Tags available
 
+* `34`
+* `34-emulator`
+* `34-ndk`
+* `34-stf-client`
+* `34-jdk11`
 * `33`
 * `33-emulator`
 * `33-ndk`
@@ -37,13 +42,6 @@ An image that lets us build android apps with docker using gitlab-ci
 * `28-ndk`
 * `28-stf-client`
 
-## Build command
-
-```bash
-./update.sh
-docker build -t ekreative/android:latest 30
-```
-
 ## Build an app
 
 ```bash
@@ -58,6 +56,15 @@ android-start-emulator
 /gradlew cAT
 ```
 
+## Contributing
+
+This repo stores commited versions of Dockerfiles generated using the `./update.sh` script.
+To update the Dockerfiles, run `./update.sh` and commit the changes.
+When adding new versions remember to update the github workflow so that it builds them all.
+I tend to remove an older version when adding a new one. To keep just the last 2-3 versions being built. Remove old
+versions from the `Dockerfile`.
+You should also update the list of tags in the README.md file.
+
 ## Credit
 
 Borrowed a few ideas from [jacekmarchwicki/android](https://hub.docker.com/r/jacekmarchwicki/android/)