Retry curl when it failed during download

hack/lib/etcd.sh

@@ -74,12 +74,16 @@ kube::etcd::install() {
     cd "${KUBE_ROOT}/third_party"
     if [[ $(uname) == "Darwin" ]]; then
       download_file="etcd-v${ETCD_VERSION}-darwin-amd64.zip"
-      curl -fsSLO --retry 3 --keepalive-time 2 https://github.com/coreos/etcd/releases/download/v${ETCD_VERSION}/"${download_file}"
+      url="https://github.com/coreos/etcd/releases/download/v${ETCD_VERSION}/${download_file}"
+      kube::util::download_file "${url}" "${download_file}"
       unzip -o "${download_file}"
       ln -fns "etcd-v${ETCD_VERSION}-darwin-amd64" etcd
       rm "${download_file}"
     else
-      curl -fsSL --retry 3 --keepalive-time 2 https://github.com/coreos/etcd/releases/download/v${ETCD_VERSION}/etcd-v${ETCD_VERSION}-linux-amd64.tar.gz | tar xzf -
+      url="https://github.com/coreos/etcd/releases/download/v${ETCD_VERSION}/etcd-v${ETCD_VERSION}-linux-amd64.tar.gz"
+      download_file="etcd-v${ETCD_VERSION}-linux-amd64.tar.gz"
+      kube::util::download_file "${url}" "${download_file}"
+      tar xzf "${download_file}"
       ln -fns "etcd-v${ETCD_VERSION}-linux-amd64" etcd
     fi
     kube::log::info "etcd v${ETCD_VERSION} installed. To use:"

hack/lib/util.sh

@@ -478,4 +478,23 @@ kube::util::has_changes_against_upstream_branch() {
   return 1
 }
 
+kube::util::download_file() {
+  local -r url=$1
+  local -r destination_file=$2
+
+  rm  ${destination_file} 2&> /dev/null || true
+
+  for i in $(seq 5)
+  do
+    if ! curl -fsSL --retry 3 --keepalive-time 2 ${url} -o ${destination_file}; then
+      echo "Downloading ${url} failed. $((5-i)) retries left."
+      sleep 1
+    else
+      echo "Downloading ${url} succeed"
+      return 0
+    fi
+  done
+  return 1
+}
+
 # ex: ts=2 sw=2 et filetype=sh