diff --git a/build.sh b/build.sh
index 52ee9cd..0bd1e18 100755
--- a/build.sh
+++ b/build.sh
@@ -56,6 +56,9 @@
 # Override the docker image name used.
 DOCKER_IMAGE_NAME=${DOCKER_IMAGE_NAME-}
 
+# When building a docker container, these are the files that will sent and available.
+DOCKER_EXTRA_CONTEXT="lang/ruby/Gemfile lang/ruby/avro.gemspec lang/ruby/Manifest share/VERSION.txt"
+
 usage() {
   echo "Usage: $0 {lint|test|dist|sign|clean|veryclean|docker [--args \"docker-args\"]|rat|githooks|docker-test}"
   exit 1
@@ -300,8 +303,9 @@
         echo "RUN getent group $GROUP_ID || groupadd -g $GROUP_ID $USER_NAME"
         echo "RUN getent passwd $USER_ID || useradd -g $GROUP_ID -u $USER_ID -k /root -m $USER_NAME"
       } > Dockerfile
+      # Include the ruby gemspec for preinstallation.
       # shellcheck disable=SC2086
-      tar -cf- lang/ruby/Gemfile Dockerfile | docker build $DOCKER_BUILD_XTRA_ARGS -t "$DOCKER_IMAGE_NAME" -
+      tar -cf- Dockerfile $DOCKER_EXTRA_CONTEXT | docker build $DOCKER_BUILD_XTRA_ARGS -t "$DOCKER_IMAGE_NAME" -
       rm Dockerfile
       # By mapping the .m2 directory you can do an mvn install from
       # within the container and use the result on your normal
@@ -336,7 +340,7 @@
       ;;
 
     docker-test)
-      tar -cf- share/docker/Dockerfile lang/ruby/Gemfile |
+      tar -cf- share/docker/Dockerfile $DOCKER_EXTRA_CONTEXT |
         docker build -t avro-test -f share/docker/Dockerfile -
       docker run --rm -v "${PWD}:/avro${DOCKER_MOUNT_FLAG}" --env "JAVA=${JAVA:-8}" avro-test /avro/share/docker/run-tests.sh
       ;;
diff --git a/share/docker/Dockerfile b/share/docker/Dockerfile
index 7d91603..b67747f 100644
--- a/share/docker/Dockerfile
+++ b/share/docker/Dockerfile
@@ -179,6 +179,12 @@
 # Install Ruby
 RUN apt-get -qqy install ruby-full \
  && apt-get -qqy clean
+RUN mkdir -p /tmp/lang/ruby/lib/avro && mkdir -p /tmp/share
+COPY lang/ruby/* /tmp/lang/ruby/
+COPY share/VERSION.txt /tmp/share/
+RUN gem install bundler --no-document && \
+    apt-get install -qqy libyaml-dev && \
+    cd /tmp/lang/ruby && bundle install
 
 # Install Rust
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain 1.60.0