From 802e1b99b2e11fb30660d076951fbb79258e670d Mon Sep 17 00:00:00 2001
From: Adam Cozzette <acozzette@google.com>
Date: Tue, 11 Feb 2020 11:17:35 -0800
Subject: [PATCH] Attempt to mitigate "docker pull" failures

Lots of CI tests have been failing recently with error messages like
this from "docker pull":

  Error response from daemon: unexpected EOF

This seems to be an issue affecting other projects as well:
https://forums.docker.com/t/docker-pull-causes-error-response-from-daemon-unexpected-eof/88608

This commit tries to mitigate the problem by periodically retrying
failed Docker pulls.
---
 kokoro/linux/build_and_run_docker.sh | 5 +++--
 kokoro/linux/cpp_distcheck/build.sh  | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kokoro/linux/build_and_run_docker.sh b/kokoro/linux/build_and_run_docker.sh
index 3dc5dbb82f..cdbd6e29b0 100755
--- a/kokoro/linux/build_and_run_docker.sh
+++ b/kokoro/linux/build_and_run_docker.sh
@@ -28,8 +28,9 @@ else
   DOCKER_IMAGE_NAME=${DOCKERHUB_ORGANIZATION}/${DOCKERFILE_PREFIX}_$(sha1sum $DOCKERFILE_DIR/Dockerfile | cut -f1 -d\ )
 fi
 
-# Pull dockerimage from Dockerhub
-docker pull $DOCKER_IMAGE_NAME
+# Pull dockerimage from Dockerhub. This sometimes fails intermittently, so we
+# keep trying until we succeed.
+until docker pull $DOCKER_IMAGE_NAME; do sleep 10; done
 
 # Ensure existence of ccache directory
 CCACHE_DIR=/tmp/protobuf-ccache
diff --git a/kokoro/linux/cpp_distcheck/build.sh b/kokoro/linux/cpp_distcheck/build.sh
index 1343a8cc84..42ac88caff 100755
--- a/kokoro/linux/cpp_distcheck/build.sh
+++ b/kokoro/linux/cpp_distcheck/build.sh
@@ -11,7 +11,7 @@ cd $(dirname $0)/../../..
 
 # Run tests under release docker image.
 DOCKER_IMAGE_NAME=protobuf/protoc_$(sha1sum protoc-artifacts/Dockerfile | cut -f1 -d " ")
-docker pull $DOCKER_IMAGE_NAME
+until docker pull $DOCKER_IMAGE_NAME; do sleep 10; done
 
 docker run -v $(pwd):/var/local/protobuf --rm $DOCKER_IMAGE_NAME \
   bash -l /var/local/protobuf/tests.sh cpp || FAILED="true"