Add Ubuntu as a platform for e2e tests on GCE

cluster/common.sh

@@ -450,8 +450,8 @@ function find-release-tars() {
 
   # This tarball is used by GCI, Ubuntu Trusty, and Container Linux.
   KUBE_MANIFESTS_TAR=
-  if [[ "${MASTER_OS_DISTRIBUTION:-}" == "trusty" || "${MASTER_OS_DISTRIBUTION:-}" == "gci" || "${MASTER_OS_DISTRIBUTION:-}" == "container-linux" ]] || \
-     [[ "${NODE_OS_DISTRIBUTION:-}" == "trusty" || "${NODE_OS_DISTRIBUTION:-}" == "gci" || "${NODE_OS_DISTRIBUTION:-}" == "container-linux" ]] ; then
+  if [[ "${MASTER_OS_DISTRIBUTION:-}" == "trusty" || "${MASTER_OS_DISTRIBUTION:-}" == "gci" || "${MASTER_OS_DISTRIBUTION:-}" == "container-linux" || "${MASTER_OS_DISTRIBUTION:-}" == "ubuntu" ]] || \
+     [[ "${NODE_OS_DISTRIBUTION:-}" == "trusty" || "${NODE_OS_DISTRIBUTION:-}" == "gci" || "${NODE_OS_DISTRIBUTION:-}" == "container-linux" || "${NODE_OS_DISTRIBUTION:-}" == "ubuntu" ]] ; then
     KUBE_MANIFESTS_TAR=$(find-tar kubernetes-manifests.tar.gz)
   fi
 }
@@ -587,7 +587,9 @@ function build-kube-env {
   local salt_tar_url=$SALT_TAR_URL
   local kube_manifests_tar_url="${KUBE_MANIFESTS_TAR_URL:-}"
   if [[ "${master}" == "true" && "${MASTER_OS_DISTRIBUTION}" == "container-linux" ]] || \
-     [[ "${master}" == "false" && "${NODE_OS_DISTRIBUTION}" == "container-linux" ]] ; then
+     [[ "${master}" == "false" && "${NODE_OS_DISTRIBUTION}" == "container-linux" ]] || \
+     [[ "${master}" == "true" && "${MASTER_OS_DISTRIBUTION}" == "ubuntu" ]] || \
+     [[ "${master}" == "false" && "${NODE_OS_DISTRIBUTION}" == "ubuntu" ]] ; then
     # TODO: Support fallback .tar.gz settings on Container Linux
     server_binary_tar_url=$(split_csv "${SERVER_BINARY_TAR_URL}")
     salt_tar_url=$(split_csv "${SALT_TAR_URL}")
@@ -671,8 +673,8 @@ EOF
 TERMINATED_POD_GC_THRESHOLD: $(yaml-quote ${TERMINATED_POD_GC_THRESHOLD})
 EOF
   fi
-  if [[ "${master}" == "true" && ("${MASTER_OS_DISTRIBUTION}" == "trusty" || "${MASTER_OS_DISTRIBUTION}" == "gci" || "${MASTER_OS_DISTRIBUTION}" == "container-linux") ]] || \
-     [[ "${master}" == "false" && ("${NODE_OS_DISTRIBUTION}" == "trusty" || "${NODE_OS_DISTRIBUTION}" == "gci" || "${NODE_OS_DISTRIBUTION}" == "container-linux") ]] ; then
+  if [[ "${master}" == "true" && ("${MASTER_OS_DISTRIBUTION}" == "trusty" || "${MASTER_OS_DISTRIBUTION}" == "gci" || "${MASTER_OS_DISTRIBUTION}" == "container-linux") || "${MASTER_OS_DISTRIBUTION}" == "ubuntu" ]] || \
+     [[ "${master}" == "false" && ("${NODE_OS_DISTRIBUTION}" == "trusty" || "${NODE_OS_DISTRIBUTION}" == "gci" || "${NODE_OS_DISTRIBUTION}" == "container-linux") || "${NODE_OS_DISTRIBUTION}" = "ubuntu" ]] ; then
     cat >>$file <<EOF
 KUBE_MANIFESTS_TAR_URL: $(yaml-quote ${kube_manifests_tar_url})
 KUBE_MANIFESTS_TAR_HASH: $(yaml-quote ${KUBE_MANIFESTS_TAR_HASH})

cluster/gce/ubuntu/README.md

+# Ubuntu Image
+
+The Ubuntu GKE image is an image optimized to run Kubernetes on the Google
+Cloud Platform.
+
+The image is currently made to behave as much as possible like the GCI image,
+but since it uses "real" systemd (instead of upstart with a delegate), the systemd
+targets need to be changed slightly to ensure services are always started on
+boot.
+
+In practice this means that for now the only changes are in master.yaml and node.yaml,
+as well as their injection points in node-helper.sh and master-helper.sh.

cluster/gce/ubuntu/master-helper.sh

+#!/bin/bash
+
+# Copyright 2016 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.
+
+# A library of helper functions and constant for GCI distro
+source "${KUBE_ROOT}/cluster/gce/gci/helper.sh"
+
+# create-master-instance creates the master instance. If called with
+# an argument, the argument is used as the name to a reserved IP
+# address for the master. (In the case of upgrade/repair, we re-use
+# the same IP.)
+#
+# It requires a whole slew of assumed variables, partially due to to
+# the call to write-master-env. Listing them would be rather
+# futile. Instead, we list the required calls to ensure any additional
+#
+# variables are set:
+#   ensure-temp-dir
+#   detect-project
+#   get-bearer-token
+function create-master-instance {
+  local address_opt=""
+  [[ -n ${1:-} ]] && address_opt="--address ${1}"
+
+  write-master-env
+  ensure-gci-metadata-files
+  create-master-instance-internal "${MASTER_NAME}" "${address_opt}"
+}
+
+function replicate-master-instance() {
+  local existing_master_zone="${1}"
+  local existing_master_name="${2}"
+  local existing_master_replicas="${3}"
+
+  local kube_env="$(get-metadata "${existing_master_zone}" "${existing_master_name}" kube-env)"
+  # Substitute INITIAL_ETCD_CLUSTER to enable etcd clustering.
+  kube_env="$(echo "${kube_env}" | grep -v "INITIAL_ETCD_CLUSTER")"
+  kube_env="$(echo -e "${kube_env}\nINITIAL_ETCD_CLUSTER: '${existing_master_replicas},${REPLICA_NAME}'")"
+
+  # Substitute INITIAL_ETCD_CLUSTER_STATE
+  kube_env="$(echo "${kube_env}" | grep -v "INITIAL_ETCD_CLUSTER_STATE")"
+  kube_env="$(echo -e "${kube_env}\nINITIAL_ETCD_CLUSTER_STATE: 'existing'")"
+
+  ETCD_CA_KEY="$(echo "${kube_env}" | grep "ETCD_CA_KEY" |  sed "s/^.*: '//" | sed "s/'$//")"
+  ETCD_CA_CERT="$(echo "${kube_env}" | grep "ETCD_CA_CERT" |  sed "s/^.*: '//" | sed "s/'$//")"
+  create-etcd-certs "${REPLICA_NAME}" "${ETCD_CA_CERT}" "${ETCD_CA_KEY}"
+
+  kube_env="$(echo "${kube_env}" | grep -v "ETCD_PEER_KEY")"
+  kube_env="$(echo -e "${kube_env}\nETCD_PEER_KEY: '${ETCD_PEER_KEY_BASE64}'")"
+  kube_env="$(echo "${kube_env}" | grep -v "ETCD_PEER_CERT")"
+  kube_env="$(echo -e "${kube_env}\nETCD_PEER_CERT: '${ETCD_PEER_CERT_BASE64}'")"
+
+  echo "${kube_env}" > ${KUBE_TEMP}/master-kube-env.yaml
+  get-metadata "${existing_master_zone}" "${existing_master_name}" cluster-name > "${KUBE_TEMP}/cluster-name.txt"
+  get-metadata "${existing_master_zone}" "${existing_master_name}" gci-update-strategy > "${KUBE_TEMP}/gci-update.txt"
+  get-metadata "${existing_master_zone}" "${existing_master_name}" gci-ensure-gke-docker > "${KUBE_TEMP}/gci-ensure-gke-docker.txt"
+  get-metadata "${existing_master_zone}" "${existing_master_name}" gci-docker-version > "${KUBE_TEMP}/gci-docker-version.txt"
+  get-metadata "${existing_master_zone}" "${existing_master_name}" kube-master-certs > "${KUBE_TEMP}/kube-master-certs.yaml"
+
+  create-master-instance-internal "${REPLICA_NAME}"
+}
+
+
+function create-master-instance-internal() {
+  local -r master_name="${1}"
+  local -r address_option="${2:-}"
+
+  local preemptible_master=""
+  if [[ "${PREEMPTIBLE_MASTER:-}" == "true" ]]; then
+    preemptible_master="--preemptible --maintenance-policy TERMINATE"
+  fi
+
+  gcloud compute instances create "${master_name}" \
+    ${address_option} \
+    --project "${PROJECT}" \
+    --zone "${ZONE}" \
+    --machine-type "${MASTER_SIZE}" \
+    --image-project="${MASTER_IMAGE_PROJECT}" \
+    --image "${MASTER_IMAGE}" \
+    --tags "${MASTER_TAG}" \
+    --network "${NETWORK}" \
+    --scopes "storage-ro,compute-rw,monitoring,logging-write" \
+    --can-ip-forward \
+    --metadata-from-file \
+      "kube-env=${KUBE_TEMP}/master-kube-env.yaml,user-data=${KUBE_ROOT}/cluster/gce/ubuntu/master.yaml,configure-sh=${KUBE_ROOT}/cluster/gce/gci/configure.sh,cluster-name=${KUBE_TEMP}/cluster-name.txt,gci-update-strategy=${KUBE_TEMP}/gci-update.txt,gci-ensure-gke-docker=${KUBE_TEMP}/gci-ensure-gke-docker.txt,gci-docker-version=${KUBE_TEMP}/gci-docker-version.txt,kube-master-certs=${KUBE_TEMP}/kube-master-certs.yaml" \
+    --disk "name=${master_name}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no" \
+    --boot-disk-size "${MASTER_ROOT_DISK_SIZE:-10}" \
+    ${preemptible_master}
+}
+
+function get-metadata() {
+  local zone="${1}"
+  local name="${2}"
+  local key="${3}"
+  gcloud compute ssh "${name}" \
+    --project "${PROJECT}" \
+    --zone "${zone}" \
+    --command "curl \"http://metadata.google.internal/computeMetadata/v1/instance/attributes/${key}\" -H \"Metadata-Flavor: Google\"" 2>/dev/null
+}

cluster/gce/ubuntu/master.yaml

+#cloud-config
+
+write_files:
+  - path: /etc/systemd/system/kube-master-installation.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Download and install k8s binaries and configurations
+      After=network-online.target
+
+      [Service]
+      Type=oneshot
+      RemainAfterExit=yes
+      ExecStartPre=/bin/mkdir -p /home/kubernetes/bin
+      ExecStartPre=/bin/mount --bind /home/kubernetes/bin /home/kubernetes/bin
+      ExecStartPre=/bin/mount -o remount,exec /home/kubernetes/bin
+      ExecStartPre=/usr/bin/curl --fail --retry 5 --retry-delay 3 --silent --show-error	-H "X-Google-Metadata-Request: True" -o /home/kubernetes/bin/configure.sh http://metadata.google.internal/computeMetadata/v1/instance/attributes/configure-sh
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/configure.sh
+      ExecStart=/home/kubernetes/bin/configure.sh
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-master-configuration.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Configure kubernetes master
+      After=kube-master-installation.service
+
+      [Service]
+      Type=oneshot
+      RemainAfterExit=yes
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/configure-helper.sh
+      ExecStart=/home/kubernetes/bin/configure-helper.sh
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-docker-monitor.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes health monitoring for docker
+      After=kube-master-configuration.service
+
+      [Service]
+      Restart=always
+      RestartSec=10
+      RemainAfterExit=yes
+      RemainAfterExit=yes
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/health-monitor.sh
+      ExecStart=/home/kubernetes/bin/health-monitor.sh docker
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kubelet-monitor.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes health monitoring for kubelet
+      After=kube-master-configuration.service
+
+      [Service]
+      Restart=always
+      RestartSec=10
+      RemainAfterExit=yes
+      RemainAfterExit=yes
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/health-monitor.sh
+      ExecStart=/home/kubernetes/bin/health-monitor.sh kubelet
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-logrotate.timer
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Hourly kube-logrotate invocation
+
+      [Timer]
+      OnCalendar=hourly
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-logrotate.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes log rotation
+      After=kube-master-configuration.service
+
+      [Service]
+      Type=oneshot
+      ExecStart=-/usr/sbin/logrotate /etc/logrotate.conf
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kubernetes.target
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes
+
+      [Install]
+      WantedBy=multi-user.target
+      After=docker.service
+
+runcmd:
+ - systemctl daemon-reload
+ - systemctl enable kube-master-installation.service
+ - systemctl enable kube-master-configuration.service
+ - systemctl enable kube-docker-monitor.service
+ - systemctl enable kubelet-monitor.service
+ - systemctl enable kube-logrotate.timer
+ - systemctl enable kube-logrotate.service
+ - systemctl enable kubernetes.target
+ - systemctl start kubernetes.target

cluster/gce/ubuntu/node-helper.sh

+#!/bin/bash
+
+# Copyright 2016 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.
+
+# A library of helper functions and constant for GCI distro
+source "${KUBE_ROOT}/cluster/gce/gci/helper.sh"
+
+# $1: template name (required).
+function create-node-instance-template {
+  local template_name="$1"
+  ensure-gci-metadata-files
+  create-node-template "$template_name" "${scope_flags[*]}" \
+    "kube-env=${KUBE_TEMP}/node-kube-env.yaml" \
+    "user-data=${KUBE_ROOT}/cluster/gce/ubuntu/node.yaml" \
+    "configure-sh=${KUBE_ROOT}/cluster/gce/gci/configure.sh" \
+    "cluster-name=${KUBE_TEMP}/cluster-name.txt" \
+    "gci-update-strategy=${KUBE_TEMP}/gci-update.txt" \
+    "gci-ensure-gke-docker=${KUBE_TEMP}/gci-ensure-gke-docker.txt" \
+    "gci-docker-version=${KUBE_TEMP}/gci-docker-version.txt"
+}

cluster/gce/ubuntu/node.yaml

+#cloud-config
+
+write_files:
+  - path: /etc/systemd/system/kube-node-installation.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Download and install k8s binaries and configurations
+      After=network-online.target
+
+      [Service]
+      Type=oneshot
+      RemainAfterExit=yes
+      ExecStartPre=/bin/mkdir -p /home/kubernetes/bin
+      ExecStartPre=/bin/mount --bind /home/kubernetes/bin /home/kubernetes/bin
+      ExecStartPre=/bin/mount -o remount,exec /home/kubernetes/bin
+      ExecStartPre=/usr/bin/curl --fail --retry 5 --retry-delay 3 --silent --show-error	-H "X-Google-Metadata-Request: True" -o /home/kubernetes/bin/configure.sh http://metadata.google.internal/computeMetadata/v1/instance/attributes/configure-sh
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/configure.sh
+      ExecStart=/home/kubernetes/bin/configure.sh
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-node-configuration.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Configure kubernetes node
+      After=kube-node-installation.service
+
+      [Service]
+      Type=oneshot
+      RemainAfterExit=yes
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/configure-helper.sh
+      ExecStart=/home/kubernetes/bin/configure-helper.sh
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-docker-monitor.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes health monitoring for docker
+      After=kube-node-configuration.service
+
+      [Service]
+      Restart=always
+      RestartSec=10
+      RemainAfterExit=yes
+      RemainAfterExit=yes
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/health-monitor.sh
+      ExecStart=/home/kubernetes/bin/health-monitor.sh docker
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kubelet-monitor.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes health monitoring for kubelet
+      After=kube-node-configuration.service
+
+      [Service]
+      Restart=always
+      RestartSec=10
+      RemainAfterExit=yes
+      RemainAfterExit=yes
+      ExecStartPre=/bin/chmod 544 /home/kubernetes/bin/health-monitor.sh
+      ExecStart=/home/kubernetes/bin/health-monitor.sh kubelet
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-logrotate.timer
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Hourly kube-logrotate invocation
+
+      [Timer]
+      OnCalendar=hourly
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kube-logrotate.service
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes log rotation
+      After=kube-node-configuration.service
+
+      [Service]
+      Type=oneshot
+      ExecStart=-/usr/sbin/logrotate /etc/logrotate.conf
+
+      [Install]
+      WantedBy=kubernetes.target
+
+  - path: /etc/systemd/system/kubernetes.target
+    permissions: 0644
+    owner: root
+    content: |
+      [Unit]
+      Description=Kubernetes
+
+      [Install]
+      WantedBy=multi-user.target
+      After=docker.service
+
+runcmd:
+ - systemctl daemon-reload
+ - systemctl enable kube-node-installation.service
+ - systemctl enable kube-node-configuration.service
+ - systemctl enable kube-docker-monitor.service
+ - systemctl enable kubelet-monitor.service
+ - systemctl enable kube-logrotate.timer
+ - systemctl enable kube-logrotate.service
+ - systemctl enable kubernetes.target
+ - systemctl start kubernetes.target

cluster/gce/util.sh

@@ -23,14 +23,14 @@ source "${KUBE_ROOT}/cluster/gce/${KUBE_CONFIG_FILE-"config-default.sh"}"
 source "${KUBE_ROOT}/cluster/common.sh"
 source "${KUBE_ROOT}/hack/lib/util.sh"
 
-if [[ "${NODE_OS_DISTRIBUTION}" == "debian" || "${NODE_OS_DISTRIBUTION}" == "container-linux" || "${NODE_OS_DISTRIBUTION}" == "trusty" || "${NODE_OS_DISTRIBUTION}" == "gci" ]]; then
+if [[ "${NODE_OS_DISTRIBUTION}" == "debian" || "${NODE_OS_DISTRIBUTION}" == "container-linux" || "${NODE_OS_DISTRIBUTION}" == "trusty" || "${NODE_OS_DISTRIBUTION}" == "gci" || "${NODE_OS_DISTRIBUTION}" == "ubuntu" ]]; then
   source "${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
 
-if [[ "${MASTER_OS_DISTRIBUTION}" == "container-linux" || "${MASTER_OS_DISTRIBUTION}" == "trusty" || "${MASTER_OS_DISTRIBUTION}" == "gci" ]]; then
+if [[ "${MASTER_OS_DISTRIBUTION}" == "container-linux" || "${MASTER_OS_DISTRIBUTION}" == "trusty" || "${MASTER_OS_DISTRIBUTION}" == "gci" || "${MASTER_OS_DISTRIBUTION}" == "ubuntu" ]]; then
   source "${KUBE_ROOT}/cluster/gce/${MASTER_OS_DISTRIBUTION}/master-helper.sh"
 else
   echo "Cannot operate on cluster using master os distro: ${MASTER_OS_DISTRIBUTION}" >&2
@@ -45,10 +45,13 @@ if [[ "${MASTER_OS_DISTRIBUTION}" == "gci" ]]; then
 elif [[ "${MASTER_OS_DISTRIBUTION}" == "debian" ]]; then
   MASTER_IMAGE=${KUBE_GCE_MASTER_IMAGE:-${CVM_VERSION}}
   MASTER_IMAGE_PROJECT=${KUBE_GCE_MASTER_PROJECT:-google-containers}
+elif [[ "${MASTER_OS_DISTRIBUTION}" == "ubuntu" ]]; then
+  MASTER_IMAGE=${KUBE_GCE_MASTER_IMAGE}
+  MASTER_IMAGE_PROJECT=${KUBE_GCE_MASTER_PROJECT}
 fi
 
 # Sets node image based on the specified os distro. Currently this function only
-# supports gci and debian.
+# supports gci, debian, and ubuntu.
 function set-node-image() {
   if [[ "${NODE_OS_DISTRIBUTION}" == "gci" ]]; then
     # If the node image is not set, we use the latest GCI image.
@@ -58,6 +61,9 @@ function set-node-image() {
   elif [[ "${NODE_OS_DISTRIBUTION}" == "debian" ]]; then
     NODE_IMAGE=${KUBE_GCE_NODE_IMAGE:-${CVM_VERSION}}
     NODE_IMAGE_PROJECT=${KUBE_GCE_NODE_PROJECT:-google-containers}
+  elif [[ "${NODE_OS_DISTRIBUTION}" == "ubuntu" ]]; then
+    NODE_IMAGE=${KUBE_GCE_NODE_IMAGE}
+    NODE_IMAGE_PROJECT=${KUBE_GCE_NODE_PROJECT}
   fi
 }
 
@@ -643,8 +649,8 @@ function kube-up() {
     create-subnetwork
     create-nodes
   elif [[ ${KUBE_REPLICATE_EXISTING_MASTER:-} == "true" ]]; then
-    if  [[ "${MASTER_OS_DISTRIBUTION}" != "gci" && "${MASTER_OS_DISTRIBUTION}" != "debian" ]]; then
-      echo "Master replication supported only for gci and debian"
+    if  [[ "${MASTER_OS_DISTRIBUTION}" != "gci" && "${MASTER_OS_DISTRIBUTION}" != "debian" && "${MASTER_OS_DISTRIBUTION}" != "ubuntu" ]]; then
+      echo "Master replication supported only for gci, debian, and ubuntu"
       return 1
     fi
     create-loadbalancer