From d53b5f1f2e781c24b8be947aebb8d90cb8f994db Mon Sep 17 00:00:00 2001
From: Ryan Hitchman <rmmh@google.com>
Date: Thu, 12 Apr 2018 15:14:46 -0700
Subject: [PATCH] Add a GCS mirror to WORKSPACE URLs. //hack:update-mirror
 updates it.

This will help avoid flakes when initializing WORKSPACE, since there are
two sources for each file. Any errors downloading or failed hashes cause
bazel to try the next url in the series.
---
 build/root/WORKSPACE            | 17 +++++++----
 build/workspace_mirror.bzl      | 53 +++++++++++++++++++++++++++++++++
 hack/BUILD                      |  7 +++++
 hack/update-workspace-mirror.sh | 43 ++++++++++++++++++++++++++
 4 files changed, 114 insertions(+), 6 deletions(-)
 create mode 100644 build/workspace_mirror.bzl
 create mode 100755 hack/update-workspace-mirror.sh

diff --git a/build/root/WORKSPACE b/build/root/WORKSPACE
index 6f3a3df39ce..c6ea40e4eca 100644
--- a/build/root/WORKSPACE
+++ b/build/root/WORKSPACE
@@ -1,21 +1,23 @@
+load("//build:workspace_mirror.bzl", "mirror")
+
 http_archive(
     name = "io_bazel_rules_go",
     sha256 = "4b2c61795ac2eefcb28f3eb8e1cb2d8fb3c2eafa0f6712473bc5f93728f38758",
-    urls = ["https://github.com/bazelbuild/rules_go/releases/download/0.10.2/rules_go-0.10.2.tar.gz"],
+    urls = mirror("https://github.com/bazelbuild/rules_go/releases/download/0.10.2/rules_go-0.10.2.tar.gz"),
 )
 
 http_archive(
     name = "io_kubernetes_build",
     sha256 = "007774f06536059f3f782d1a092bddc625d88c17f20bbe731cea844a52485b11",
     strip_prefix = "repo-infra-97099dccc8807e9159dc28f374a8f0602cab07e1",
-    urls = ["https://github.com/kubernetes/repo-infra/archive/97099dccc8807e9159dc28f374a8f0602cab07e1.tar.gz"],
+    urls = mirror("https://github.com/kubernetes/repo-infra/archive/97099dccc8807e9159dc28f374a8f0602cab07e1.tar.gz"),
 )
 
 http_archive(
     name = "bazel_skylib",
     sha256 = "bbccf674aa441c266df9894182d80de104cabd19be98be002f6d478aaa31574d",
     strip_prefix = "bazel-skylib-2169ae1c374aab4a09aa90e65efe1a3aad4e279b",
-    urls = ["https://github.com/bazelbuild/bazel-skylib/archive/2169ae1c374aab4a09aa90e65efe1a3aad4e279b.tar.gz"],
+    urls = mirror("https://github.com/bazelbuild/bazel-skylib/archive/2169ae1c374aab4a09aa90e65efe1a3aad4e279b.tar.gz"),
 )
 
 ETCD_VERSION = "3.2.18"
@@ -25,14 +27,14 @@ new_http_archive(
     build_file = "third_party/etcd.BUILD",
     sha256 = "b729db0732448064271ea6fdcb901773c4fe917763ca07776f22d0e5e0bd4097",
     strip_prefix = "etcd-v%s-linux-amd64" % ETCD_VERSION,
-    urls = ["https://github.com/coreos/etcd/releases/download/v%s/etcd-v%s-linux-amd64.tar.gz" % (ETCD_VERSION, ETCD_VERSION)],
+    urls = mirror("https://github.com/coreos/etcd/releases/download/v%s/etcd-v%s-linux-amd64.tar.gz" % (ETCD_VERSION, ETCD_VERSION)),
 )
 
 http_archive(
     name = "io_bazel_rules_docker",
     sha256 = "c440717ee9b1b2f4a1e9bf5622539feb5aef9db83fc1fa1517818f13c041b0be",
     strip_prefix = "rules_docker-8bbe2a8abd382641e65ff7127a3700a8530f02ce",
-    urls = ["https://github.com/bazelbuild/rules_docker/archive/8bbe2a8abd382641e65ff7127a3700a8530f02ce.tar.gz"],
+    urls = mirror("https://github.com/bazelbuild/rules_docker/archive/8bbe2a8abd382641e65ff7127a3700a8530f02ce.tar.gz"),
 )
 
 load("@bazel_skylib//:lib.bzl", "versions")
@@ -53,7 +55,7 @@ docker_repositories()
 http_file(
     name = "kubernetes_cni",
     sha256 = "f04339a21b8edf76d415e7f17b620e63b8f37a76b2f706671587ab6464411f2d",
-    url = "https://storage.googleapis.com/kubernetes-release/network-plugins/cni-plugins-amd64-v0.6.0.tgz",
+    urls = mirror("https://storage.googleapis.com/kubernetes-release/network-plugins/cni-plugins-amd64-v0.6.0.tgz"),
 )
 
 docker_pull(
@@ -79,3 +81,6 @@ docker_pull(
     repository = "library/busybox",
     tag = "latest",  # ignored, but kept here for documentation
 )
+
+load("//build:workspace_mirror.bzl", "export_urls")
+export_urls("workspace_urls")
diff --git a/build/workspace_mirror.bzl b/build/workspace_mirror.bzl
new file mode 100644
index 00000000000..bbc02c88a76
--- /dev/null
+++ b/build/workspace_mirror.bzl
@@ -0,0 +1,53 @@
+# Copyright 2018 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+prefix = "https://storage.googleapis.com/k8s-bazel-cache/"
+
+def mirror(url):
+  """Try downloading a URL from a GCS mirror first, then from the original.
+
+  Update the GCS bucket using bazel run //hack:update-mirror"""
+  return [prefix + url, url]
+
+# This function only gives proper results when executed from WORKSPACE,
+# but the data is needed in sh_binary, which can only be in a BUILD file.
+# Thus, it is be exported by a repository_rule (which executes in WORKSPACE)
+# to be used by the sh_binary.
+def mirror_urls():
+  urls = []
+  for k, v in native.existing_rules().items():
+    us = list(v.get('urls', []))
+    if 'url' in v:
+      us.append(v['url'])
+    for u in us:
+      if u and not u.startswith(prefix):
+        urls.append(u)
+  return sorted(urls)
+
+def export_urls_impl(repo_ctx):
+  repo_ctx.file(repo_ctx.path("BUILD.bazel"), """
+exports_files(glob(["**"]), visibility=["//visibility:public"])
+""")
+  repo_ctx.file(repo_ctx.path("urls.txt"), content="\n".join(repo_ctx.attr.urls))
+
+_export_urls = repository_rule(
+    attrs = {
+        "urls": attr.string_list(mandatory = True),
+    },
+    local = True,
+    implementation = export_urls_impl,
+)
+
+def export_urls(name):
+  return _export_urls(name=name, urls=mirror_urls())
diff --git a/hack/BUILD b/hack/BUILD
index d562a44883b..f502e144403 100644
--- a/hack/BUILD
+++ b/hack/BUILD
@@ -72,3 +72,10 @@ go_library(
     srcs = ["e2e.go"],
     importpath = "k8s.io/kubernetes/hack",
 )
+
+sh_binary(
+    name = "update-mirror",
+    srcs = ["update-workspace-mirror.sh"],
+    args = ["$(location @workspace_urls//:urls.txt)"],
+    data = ["@workspace_urls//:urls.txt"],
+)
diff --git a/hack/update-workspace-mirror.sh b/hack/update-workspace-mirror.sh
new file mode 100755
index 00000000000..9b7c456c994
--- /dev/null
+++ b/hack/update-workspace-mirror.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+
+# Copyright 2018 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+if [[ $# -ne 1 ]]; then
+    echo 'use "bazel run //build:update-mirror"'
+    echo "(usage: $0 <file with list of URLs to mirror>)"
+    exit 1
+fi
+
+BUCKET="gs://k8s-bazel-cache"
+
+gsutil acl get "${BUCKET}" > /dev/null
+
+tmpfile=$(mktemp bazel_workspace_mirror.XXXXXX)
+trap "rm ${tmpfile}" EXIT
+cat "$1" | while read url; do
+  echo "${url}"
+  if gsutil ls "${BUCKET}/${url}" &> /dev/null; then
+    echo present
+  else
+    echo missing
+    if curl -fLag "${url}" > "${tmpfile}"; then
+        gsutil cp -a public-read "${tmpfile}" "${BUCKET}/${url}"
+    fi
+  fi
+done