Merge pull request #54403 from wojtek-t/dont_hardcode_etcd_hostname

Automatic merge from submit-queue (batch tested with PRs 54400, 54403). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Allow for configuring etcd hostname in the manifest

```release-note
Allow for configuring etcd hostname in the manifest
```

cluster/common.sh

@@ -842,6 +842,11 @@ EOF
     if [ -n "${ETCD_VERSION:-}" ]; then
       cat >>$file <<EOF
 ETCD_VERSION: $(yaml-quote ${ETCD_VERSION})
+EOF
+    fi
+    if [ -n "${ETCD_HOSTNAME:-}" ]; then
+      cat >>$file <<EOF
+ETCD_HOSTNAME: $(yaml-quote ${ETCD_HOSTNAME})
 EOF
     fi
     if [ -n "${APISERVER_TEST_ARGS:-}" ]; then

cluster/gce/configure-vm.sh

@@ -447,7 +447,7 @@ kube_uid: '$(echo "${KUBE_UID}" | sed -e "s/'/''/g")'
 initial_etcd_cluster: '$(echo "${INITIAL_ETCD_CLUSTER:-}" | sed -e "s/'/''/g")'
 initial_etcd_cluster_state: '$(echo "${INITIAL_ETCD_CLUSTER_STATE:-}" | sed -e "s/'/''/g")'
 ca_cert_bundle_path: '$(echo "${CA_CERT_BUNDLE_PATH:-}" | sed -e "s/'/''/g")'
-hostname: $(hostname -s)
+hostname: '$(echo "${ETCD_HOSTNAME:-$(hostname -s)}" | sed -e "s/'/''/g")'
 enable_pod_priority: '$(echo "${ENABLE_POD_PRIORITY:-}" | sed -e "s/'/''/g")'
 enable_default_storage_class: '$(echo "$ENABLE_DEFAULT_STORAGE_CLASS" | sed -e "s/'/''/g")'
 kube_proxy_daemonset: '$(echo "$KUBE_PROXY_DAEMONSET" | sed -e "s/'/''/g")'

cluster/gce/container-linux/configure-helper.sh

@@ -730,7 +730,7 @@ function start-kube-proxy {
 # $4: value for variable 'cpulimit'
 # $5: pod name, which should be either etcd or etcd-events
 function prepare-etcd-manifest {
-  local host_name=$(hostname -s)
+  local host_name=${ETCD_HOSTNAME:-$(hostname -s)}
   local etcd_cluster=""
   local cluster_state="new"
   local etcd_protocol="http"

cluster/gce/gci/configure-helper.sh

@@ -1119,7 +1119,7 @@ function start-kube-proxy {
 # $4: value for variable 'cpulimit'
 # $5: pod name, which should be either etcd or etcd-events
 function prepare-etcd-manifest {
-  local host_name=$(hostname)
+  local host_name=${ETCD_HOSTNAME:-$(hostname -s)}
   local etcd_cluster=""
   local cluster_state="new"
   local etcd_protocol="http"