MASTER_OS_DISTRIBUTION=${KUBE_MASTER_OS_DISTRIBUTION:-${KUBE_OS_DISTRIBUTION:-gci}}
NODE_OS_DISTRIBUTION=${KUBE_NODE_OS_DISTRIBUTION:-${KUBE_OS_DISTRIBUTION:-gci}}
WINDOWS_NODE_OS_DISTRIBUTION=${WINDOWS_NODE_OS_DISTRIBUTION:-win2019}

if [[ "${MASTER_OS_DISTRIBUTION}" = 'cos' ]]; then
  MASTER_OS_DISTRIBUTION='gci'
fi

if [[ "${NODE_OS_DISTRIBUTION}" = 'cos' ]]; then
  NODE_OS_DISTRIBUTION='gci'
fi

  --dns-domain="${KUBE_DNS_DOMAIN:-cluster.local}" \
  --prepull-images="${PREPULL_IMAGES:-false}" \
  ${MASTER_OS_DISTRIBUTION:+"--master-os-distro=${MASTER_OS_DISTRIBUTION}"} \
  ${NODE_OS_DISTRIBUTION:+"--node-os-distro=${NODE_OS_DISTRIBUTION}"} \
  ${NUM_NODES:+"--num-nodes=${NUM_NODES}"} \
  ${E2E_REPORT_DIR:+"--report-dir=${E2E_REPORT_DIR}"} \
  ${E2E_REPORT_PREFIX:+"--report-prefix=${E2E_REPORT_PREFIX}"} \

  if [[ "${MASTER_OS_DISTRIBUTION:-}" == "trusty" || "${MASTER_OS_DISTRIBUTION:-}" == "gci" || "${MASTER_OS_DISTRIBUTION:-}" == "ubuntu" ]] || \
     [[ "${NODE_OS_DISTRIBUTION:-}" == "trusty" || "${NODE_OS_DISTRIBUTION:-}" == "gci" || "${NODE_OS_DISTRIBUTION:-}" == "ubuntu" || "${NODE_OS_DISTRIBUTION:-}" == "custom" ]] ; then
    if KUBE_MANIFESTS_TAR=$(find-tar kubernetes-manifests.tar.gz); then
      find_result=0
    else
      find_result=1

MASTER_OS_DISTRIBUTION=${KUBE_MASTER_OS_DISTRIBUTION:-${KUBE_OS_DISTRIBUTION:-gci}}
NODE_OS_DISTRIBUTION=${KUBE_NODE_OS_DISTRIBUTION:-${KUBE_OS_DISTRIBUTION:-gci}}
WINDOWS_NODE_OS_DISTRIBUTION=${WINDOWS_NODE_OS_DISTRIBUTION:-win2019}

if [[ "${MASTER_OS_DISTRIBUTION}" == "cos" ]]; then
    MASTER_OS_DISTRIBUTION="gci"
fi

if [[ "${NODE_OS_DISTRIBUTION}" == "cos" ]]; then
    NODE_OS_DISTRIBUTION="gci"
fi

    echo "== Ensuring that new Node base OS image matched the existing Node base OS image"
    NODE_OS_DISTRIBUTION=$(get-node-os "${NODE_NAMES[0]}")

    if [[ "${NODE_OS_DISTRIBUTION}" == "cos" ]]; then
        NODE_OS_DISTRIBUTION="gci"
    fi

    source "${KUBE_ROOT}/cluster/gce/${NODE_OS_DISTRIBUTION}/node-helper.sh"
    # Reset the node image based on current os distro
    set-linux-node-image
  fi
}

source "${KUBE_ROOT}/cluster/common.sh"
source "${KUBE_ROOT}/hack/lib/util.sh"

if [[ "${NODE_OS_DISTRIBUTION}" == "gci" || "${NODE_OS_DISTRIBUTION}" == "ubuntu" || "${NODE_OS_DISTRIBUTION}" == "custom" ]]; then
  source "${KUBE_ROOT}/cluster/gce/${NODE_OS_DISTRIBUTION}/node-helper.sh"
else
  echo "Cannot operate on cluster using node os distro: ${NODE_OS_DISTRIBUTION}" >&2
  exit 1
fi

source "${KUBE_ROOT}/cluster/gce/windows/node-helper.sh"

* Remove 'system' prefix from Metadata Agent rbac configuration ([#61394](https://github.com/kubernetes/kubernetes/pull/61394), [@kawych](https://github.com/kawych))
* Support new NODE_OS_DISTRIBUTION 'custom' on GCE on a new add event. ([#61235](https://github.com/kubernetes/kubernetes/pull/61235), [@yguo0905](https://github.com/yguo0905))

* Update Cluster Autoscaler version to 1.0.5 to fix security vulnerabilities ([#61566](https://github.com/kubernetes/kubernetes/pull/61566), [@aleksandra-malinowska](https://github.com/aleksandra-malinowska))
* Support new NODE_OS_DISTRIBUTION 'custom' on GCE ([#61235](https://github.com/kubernetes/kubernetes/pull/61235), [@yguo0905](https://github.com/yguo0905))

* [fluentd-gcp addon] Update fluentd and event-exporter images to have the latest base image. ([#61719](https://github.com/kubernetes/kubernetes/pull/61719), [@crassirostris](https://github.com/crassirostris))
* Support new NODE_OS_DISTRIBUTION 'custom' on GCE ([#61235](https://github.com/kubernetes/kubernetes/pull/61235), [@yguo0905](https://github.com/yguo0905))

* Bump Heapster to v1.5.2 ([#61396](https://github.com/kubernetes/kubernetes/pull/61396), [@kawych](https://github.com/kawych))
* Support new NODE_OS_DISTRIBUTION 'custom' on GCE ([#61235](https://github.com/kubernetes/kubernetes/pull/61235), [@yguo0905](https://github.com/yguo0905))