Kubernetes v1.6.9 is the default version for new clusters, released according to the following planned schedule:
Kubernetes v1.7.5 is available for new clusters, released according to the schedule above.
v1.7.3 will no longer be available for new clusters and master upgrades.
v1.7.4 will no longer be available for new clusters and master upgrades.
Google Container Engine's kubectl version has been updated from 1.7.4 to 1.7.5.
You can now use IP aliases with an existing subnetwork when creating a cluster. IP aliases are a Beta feature in Container Engine version 1.7.5.
The following flags are now available in gcloud beta containers create for enabling the use of IP aliases with an existing subnetwork: -enable-ip-alias, --cluster-secondary-range-name, --services-secondary-range-name.
You can now run Container Engine clusters in region southamerica-east1 (São Paulo).
(https://cloud.google.com/container-engine/release-notes#september_05_2017)