gke-networking

SKILL.md

GKE Networking

This reference covers networking configuration for GKE clusters. The golden path
enforces private, VPC-native clusters with Dataplane V2.

MCP Tools: get_cluster, update_cluster, apply_k8s_manifest,
get_k8s_resource

Golden Path Networking Defaults

Setting
Golden Path Value
Day-0/1
Notes

privateClusterConfig.enablePrivateNodes
true
Day-0
Nodes have no public IPs

masterAuthorizedNetworksConfig.privateEndpointEnforcementEnabled
true
Day-0
Control plane only reachable via private endpoint or DNS

controlPlaneEndpointsConfig.dnsEndpointConfig.allowExternalTraffic
true
Day-0
Allows DNS-based access from outside VPC

networkConfig.datapathProvider
ADVANCED_DATAPATH (Dataplane V2)
Day-0
eBPF-based, built-in Network Policy

networkConfig.dnsConfig.clusterDns
CLOUD_DNS
Day-0
Managed DNS, more reliable than kube-dns

networkConfig.enableIntraNodeVisibility
true
Day-1
VPC Flow Logs for intra-node traffic

ipAllocationPolicy.autoIpamConfig.enabled
true
Day-0
Automatic IP range management

ipAllocationPolicy.createSubnetwork
true
Day-0
Auto-create dedicated subnet

defaultMaxPodsConstraint.maxPodsPerNode
48
Day-0
Conservative default; 110 for high density

Private Cluster Access Patterns

The golden path creates a private cluster. Users access it via:

DNS endpoint (default): allowExternalTraffic: true enables access via
the cluster's DNS endpoint from outside the VPC. No VPN required.

Private endpoint: Direct access from within the VPC or via Cloud
VPN/Interconnect.

Authorized networks: Add specific CIDRs to
masterAuthorizedNetworksConfig for IP-based access control.

# Access private cluster via DNS endpoint (golden path default)
gcloud container clusters get-credentials {cluster_name} \
  --region {region} --dns-endpoint \
  --quiet

# Access via private endpoint (from within VPC)
gcloud container clusters get-credentials {cluster_name} \
  --region {region} --internal-ip \
  --quiet

Bring-Your-Own VPC/Subnet

If the customer has existing network infrastructure:

gcloud container clusters create-auto {cluster_name} \
  --region {region} \
  --network {vpc_name} \
  --subnetwork {subnet_name} \
  --cluster-secondary-range-name {pod_range} \
  --services-secondary-range-name {svc_range} \
  --enable-private-nodes \
  --enable-master-authorized-networks \
  --quiet

Day-0 Warning: VPC, subnet, and IP ranges cannot be changed after cluster
creation.

VPC-Native Mode Benefits

VPC-native clusters route traffic natively using GCP Alias IP ranges. Key
benefits to cover:

Scalability: Traffic routes natively inside the VPC, bypassing the need
for custom routes and avoiding custom route limit bottlenecks.

Direct VPC Integration: Direct resource integration across GCP networks
without complex bridging or routing tunnels.

Avoiding IP Exhaustion: Supports discontiguous IP ranges and optimizes
allocation, reducing the risk of exhausting subnet IP ranges.

IP Planning

Resource
Golden Path
Notes

Pod CIDR
/17 (auto)
~32K pod IPs; size based on maxPodsPerNode

Service CIDR
/20 (auto)
~4K service IPs

Node subnet
auto-created
/20 recommended for growth

Max pods/node
48
Each node gets a /25 pod range; set to 110

:               :              : for /24 per node                           :

Pod CIDR sizing rule of thumb:

maxPodsPerNode=48 -> each node uses a /25 (128 IPs) from pod CIDR

maxPodsPerNode=110 -> each node uses a /24 (256 IPs) from pod CIDR

Larger maxPodsPerNode = fewer nodes fit in a given CIDR

Egress

Default: nodes use Cloud NAT for outbound internet access (private nodes
have no public IPs) to allow private nodes to reach the internet without
public IP exposure.

For static egress IPs: configure Cloud NAT with manual IP allocation to
maintain a consistent source IP for external allowlists or partner
firewalls.

For restricted egress: route through a firewall appliance via custom routes
to inspect and filter outbound traffic according to organization security
policies.

Network Policy

Dataplane V2 (golden path) provides built-in Network Policy enforcement — no
additional addon needed. Apply default-deny per namespace, then allow specific
flows.

See the gke-workload-security skill for default-deny policy and the
gke-multitenancy skill for per-team allow policies.

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