elasticsearch/docs/reference/elasticsearch-plugins/discovery-gce-usage-port.md

mapped_pages
https://www.elastic.co/guide/en/elasticsearch/plugins/current/discovery-gce-usage-port.html

Changing default transport port [discovery-gce-usage-port]

By default, Elasticsearch GCE plugin assumes that you run Elasticsearch on 9300 default port. But you can specify the port value Elasticsearch is meant to use using google compute engine metadata es_port:

When creating instance [discovery-gce-usage-port-create]

Add --metadata es_port=9301 option:

# when creating first instance
gcloud compute instances create myesnode1 \
       --scopes=compute-rw,storage-full \
       --metadata es_port=9301

# when creating an instance from an image
gcloud compute instances create myesnode2 --image=elasticsearch-1-0-0-RC1 \
       --zone europe-west1-a --machine-type f1-micro --scopes=compute-rw \
       --metadata es_port=9301

On a running instance [discovery-gce-usage-port-run]

gcloud compute instances add-metadata myesnode1 \
       --zone europe-west1-a \
       --metadata es_port=9301