GKE Networking Skill | Agent Skills

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.

Agent Skills: GKE Networking

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