Squashed 'libs/protobuf/' content from commit fcd3b9a85

git-subtree-dir: libs/protobuf
git-subtree-split: fcd3b9a85ef36e46643dc30176cea1a7ad62e02b

kokoro/release/ruby/linux/prepare_build.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+# Move docker's storage location to scratch disk so we don't run out of space.
+echo 'DOCKER_OPTS="${DOCKER_OPTS} --graph=/tmpfs/docker"' | sudo tee --append /etc/default/docker
+# Use container registry mirror for pulling docker images (should make downloads faster)
+# See https://cloud.google.com/container-registry/docs/using-dockerhub-mirroring
+echo 'DOCKER_OPTS="${DOCKER_OPTS} --registry-mirror=https://mirror.gcr.io"' | sudo tee --append /etc/default/docker
+sudo service docker restart
+
+# All artifacts come here
+mkdir artifacts
+export ARTIFACT_DIR=$(pwd)/artifacts