Address review comments.

build/common.sh

@@ -949,8 +949,19 @@ function kube::release::package_kube_manifests_tarball() {
   objects=$(cd "${KUBE_ROOT}/cluster/saltbase/salt/kube-dns" && find . \( -name \*.yaml -or -name \*.yaml.in -or -name \*.json \) | grep -v demo)
   mkdir -p "${dst_dir}/dns"
   tar c -C "${KUBE_ROOT}/cluster/saltbase/salt/kube-dns" ${objects} | tar x -C "${dst_dir}/dns"
+
+  # We leave the `{{ pillar['federations_domain_map'] }}` parameter as is, if
+  # the right federation environment variables isn't set. This is to allow
+  # users to provide these pillar values using the regular salt's mechanisms
+  # during cluster bootstrap.
   if [[ "${FEDERATION:-}" == "true" ]]; then
-    sed -i 's/{{ pillar\['"'"'federations_domain_map'"'"'\] }}/- --federations="'"${FEDERATIONS_DOMAIN_MAP}"'"/g' "${dst_dir}/dns/skydns-rc.yaml.in"
+    FEDERATIONS_DOMAIN_MAP="${FEDERATIONS_DOMAIN_MAP:-}"
+    if [[ -z "${FEDERATIONS_DOMAIN_MAP}" && -n "${FEDERATION_NAME:-}" && -n "${DNS_ZONE_NAME:-}" ]]; then
+      FEDERATIONS_DOMAIN_MAP="${FEDERATION_NAME}=${DNS_ZONE_NAME}"
+    fi
+    if [[ -n "${FEDERATIONS_DOMAIN_MAP}" ]]; then
+      sed -i 's/{{ pillar\['"'"'federations_domain_map'"'"'\] }}/- --federations="'"${FEDERATIONS_DOMAIN_MAP}"'"/g' "${dst_dir}/dns/skydns-rc.yaml.in"
+    fi
   fi
 
   # This is for coreos only. ContainerVM, GCI, or Trusty does not use it.

cluster/saltbase/salt/kube-dns/skydns-rc.yaml.sed

@@ -75,7 +75,6 @@ spec:
         # command = "/kube-dns"
         - --domain=$DNS_DOMAIN.
         - --dns-port=10053
-        $FEDERATIONS_DOMAIN_MAP
         ports:
         - containerPort: 10053
           name: dns-local

cluster/saltbase/salt/kube-dns/transforms2sed.sed

 s/__PILLAR__DNS__SERVER__/$DNS_SERVER_IP/g
 s/__PILLAR__DNS__REPLICAS__/$DNS_REPLICAS/g
 s/__PILLAR__DNS__DOMAIN__/$DNS_DOMAIN/g
-s/__PILLAR__FEDERATIONS__DOMAIN__MAP__/$FEDERATIONS_DOMAIN_MAP/g
+/__PILLAR__FEDERATIONS__DOMAIN__MAP__/d
 s/__MACHINE_GENERATED_WARNING__/Warning: This is a file generated from the base underscore template file: __SOURCE_FILENAME__/g
\ No newline at end of file