Add an explicit KUBERNETES_MASTER variable to the kube-env.

cluster/gce/configure-vm.sh

@@ -77,13 +77,6 @@ import pipes,sys,yaml
 for k,v in yaml.load(sys.stdin).iteritems():
   print "readonly {var}={value}".format(var = k, value = pipes.quote(str(v)))
 ''' < "${kube_env_yaml}")
-
-  # Infer master status from hostname
-  if [[ $(hostname) == "${INSTANCE_PREFIX}-master" ]]; then
-    KUBERNETES_MASTER="true"
-  else
-    KUBERNETES_MASTER="false"
-  fi
 }
 
 function remove-docker-artifacts() {

cluster/gce/coreos/helper.sh

@@ -25,6 +25,7 @@ function build-kube-env {
   # TODO(dawnchen): master node is still running with debian image
   if [[ "${master}" == "true" ]]; then
   cat >$file <<EOF
+KUBERNETES_MASTER: "true"
 ENV_TIMESTAMP: $(yaml-quote $(date -u +%Y-%m-%dT%T%z))
 INSTANCE_PREFIX: $(yaml-quote ${INSTANCE_PREFIX})
 NODE_INSTANCE_PREFIX: $(yaml-quote ${NODE_INSTANCE_PREFIX})
@@ -60,6 +61,7 @@ KUBECFG_KEY: $(yaml-quote ${KUBECFG_KEY_BASE64:-})
 EOF
   else
     cat >>$file <<EOF
+KUBERNETES_MASTER: "false"
 ENV_TIMESTAMP=$(yaml-quote $(date -u +%Y-%m-%dT%T%z))
 INSTANCE_PREFIX=$(yaml-quote ${INSTANCE_PREFIX})
 NODE_INSTANCE_PREFIX=$(yaml-quote ${NODE_INSTANCE_PREFIX})

cluster/gce/debian/helper.sh

@@ -51,6 +51,7 @@ EOF
   if [[ "${master}" == "true" ]]; then
     # Master-only env vars.
     cat >>$file <<EOF
+KUBERNETES_MASTER: "true"
 KUBE_USER: $(yaml-quote ${KUBE_USER})
 KUBE_PASSWORD: $(yaml-quote ${KUBE_PASSWORD})
 KUBE_BEARER_TOKEN: $(yaml-quote ${KUBE_BEARER_TOKEN})
@@ -62,6 +63,7 @@ EOF
   else
     # Node-only env vars.
     cat >>$file <<EOF
+KUBERNETES_MASTER: "false"
 KUBERNETES_MASTER_NAME: $(yaml-quote ${MASTER_NAME})
 ZONE: $(yaml-quote ${ZONE})
 EXTRA_DOCKER_OPTS: $(yaml-quote ${EXTRA_DOCKER_OPTS})