Gke Networking

---
name: gke-networking
description: >-
  Plans, configures, and manages GKE networking. Covers private clusters, VPC-
  native configurations, Gateway API, DNS, ingress/egress, Dataplane V2, and
  IP planning. Use when designing GKE networking layouts, configuring private
  clusters, setting up Gateway API, planning GKE IP ranges, or configuring GKE
  ingress/egress. Don't use for basic application routing that does not
  require dedicated network configuration.
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
`networkConfig.gatewayApiConfig.channel`                             | `CHANNEL_STANDARD`                 | Day-1   | Gateway API support
`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.

```bash
# 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:

```bash
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 (e.g.
    container-native load balancing).
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

## Ingress

**Gateway API** (golden path, enabled via `gatewayApiConfig.channel:
CHANNEL_STANDARD`):

```yaml
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: external-http
spec:
  gatewayClassName: gke-l7-global-external-managed
  listeners:
  - name: http
    protocol: HTTP
    port: 80
```

**Alternatives:**

-   `gke-l7-regional-external-managed` — regional external
-   `gke-l7-rilb` — internal load balancer
-   Istio service mesh — for advanced traffic management, mTLS

## Egress

-   Default: nodes use Cloud NAT for outbound internet access (private nodes
    have no public IPs)
-   For static egress IPs: configure Cloud NAT with manual IP allocation
-   For restricted egress: route through a firewall appliance via custom routes

## 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-security` skill for default-deny policy and the
> `gke-multitenancy` skill for per-team allow policies.

## Cloud Armor (Recommended for Public-Facing Services)

Cloud Armor provides WAF and DDoS protection. **Not a golden path default** —
recommended for any service with public ingress. Link via `BackendConfig`:

```yaml
# 1. Create BackendConfig referencing your Cloud Armor policy
apiVersion: cloud.google.com/v1
kind: BackendConfig
metadata:
  name: my-backend-config
spec:
  securityPolicy:
    name: my-cloud-armor-policy
---
# 2. Annotate your Service
# cloud.google.com/backend-config: '{"default": "my-backend-config"}'
```

## SSL, Container-Native LB, and PSC

-   **Google-managed SSL certificates**: Use `ManagedCertificate` CRD with
    Gateway API. Auto-provisions and renews.
-   **Container-native LB**: Enabled by default on VPC-native clusters (golden
    path). Targets pods via NEGs, bypassing iptables. Annotation:
    `cloud.google.com/neg: '{"ingress": true}'`.
-   **Private Service Connect (PSC)**: Use `ServiceAttachment` CRD to expose
    services across VPCs without peering.