/gke-networking

name: gke-networking
description: >-
  Plans, configures, and manages core GKE cluster networking. Covers private
  clusters, VPC-native configurations, DNS, node egress, Dataplane V2, and
  IP planning. Use when designing GKE networking layouts, configuring private
  clusters, setting up Dataplane V2, planning GKE IP ranges, or managing VPC-
  native cluster modes. Don't use for application ingress, load balancing, or
  service networking (use gke-service-networking instead).
metadata:
  category: Networking

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:

1. **DNS endpoint (default)**: `allowExternalTraffic: true` enables access via the cluster's DNS endpoint from outside the VPC. No VPN required. 2. **Private endpoint**: Direct access from within the VPC or via Cloud VPN/Interconnect. 3. **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:

1. **Scalability**: Traffic routes natively inside the VPC, bypassing the need for custom routes and avoiding custom route limit bottlenecks. 2. **Direct VPC Integration**: Direct resource integration across GCP networks without complex bridging or routing tunnels. 3. **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.