Reduce the allocated IP for Cluster and Services

changelogs/unreleased/feature-reduce-cluster-ip-size.yml

+---
+title: Reduce the allocated IP for Cluster and Services
+merge_request: 18341
+author:
+type: changed

doc/user/project/clusters/add_remove_clusters.md

@@ -175,6 +175,9 @@ NOTE: **Note:**
 Starting from [GitLab 12.1](https://gitlab.com/gitlab-org/gitlab-foss/issues/55902), all GKE clusters
 created by GitLab are RBAC-enabled. Take a look at the [RBAC section](#rbac-cluster-resources) for more information.
 
+NOTE: **Note:**
+Starting from [GitLab 12.5](https://gitlab.com/gitlab-org/gitlab/merge_requests/18341), the cluster's pod address IP range will be set to /16 instead of the regular /14. (/16 is a CIDR notation)
+
 ### Cloud Run on GKE
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/merge_requests/16566) in GitLab 12.4.

lib/google_api/cloud_platform/client.rb

@@ -12,6 +12,7 @@ module GoogleApi
       SCOPE = 'https://www.googleapis.com/auth/cloud-platform'
       LEAST_TOKEN_LIFE_TIME = 10.minutes
       CLUSTER_MASTER_AUTH_USERNAME = 'admin'
+      CLUSTER_IPV4_CIDR_BLOCK = '/16'
 
       class << self
         def session_key_for_token
@@ -97,7 +98,8 @@ module GoogleApi
               enabled: legacy_abac
             },
             ip_allocation_policy: {
-              use_ip_aliases: true
+              use_ip_aliases: true,
+              cluster_ipv4_cidr_block: CLUSTER_IPV4_CIDR_BLOCK
             },
             addons_config: enable_addons.each_with_object({}) do |addon, hash|
               hash[addon] = { disabled: false }

spec/lib/google_api/cloud_platform/client_spec.rb

@@ -104,7 +104,8 @@ describe GoogleApi::CloudPlatform::Client do
             enabled: legacy_abac
           },
           ip_allocation_policy: {
-            use_ip_aliases: true
+            use_ip_aliases: true,
+            cluster_ipv4_cidr_block: '/16'
           },
           addons_config: addons_config
         }