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Using GKE Dataplane V2 | GKE networking

This page explains how to enable and troubleshoot GKE Dataplane V2 for Google Kubernetes Engine (GKE) clusters.

New Autopilot clusters have GKE Dataplane V2 enabled in versions 1.22.7-gke.1500 and later and versions 1.23.4-gke.1500 and later. If you're experiencing issues with using GKE Dataplane V2, skip to Troubleshooting.

You can enable GKE Dataplane V2 when you create new clusters with GKE version 1.20.6-gke.700 and later by using the gcloud CLI or the GKE API. You can also enable GKE Dataplane V2 in Preview when you create new clusters with GKE version 1.17.9 and later

To create a new cluster with GKE Dataplane V2, perform the following tasks:

1. In the Google Cloud console, go to the Create a Kubernetes cluster page.

   Go to Create a Kubernetes cluster

2. In the Networking section, select the Enable Dataplane V2 checkbox. The Enable Kubernetes Network Policy option is disabled when you select Enable Dataplane V2 because network policy enforcement is built into GKE Dataplane V2.

3. Click Create.

To create a new cluster with GKE Dataplane V2, use the following command:

gcloud container clusters create CLUSTER_NAME \
    --enable-dataplane-v2 \
    --enable-ip-alias \
    --release-channel CHANNEL_NAME \
    --location COMPUTE_LOCATION

Replace the following:

• CLUSTER_NAME: the name of your new cluster.
• CHANNEL_NAME: a release channel that includes GKE version 1.20.6-gke.700 or later. If you prefer not to use a release channel, you can also use the --cluster-version flag instead of --release-channel, specifying version 1.20.6-gke.700 or later.
• COMPUTE_LOCATION: the Compute Engine location for the new cluster.

To create a new cluster with GKE Dataplane V2, specify the datapathProvider field in the networkConfig object in your cluster create request.

The following JSON snippet shows the configuration needed to enable GKE Dataplane V2:

"cluster":{
   "initialClusterVersion":"VERSION",
   "ipAllocationPolicy":{
      "useIpAliases":true
   },
   "networkConfig":{
      "datapathProvider":"ADVANCED_DATAPATH"
   },
   "releaseChannel":{
      "channel":"CHANNEL_NAME"
   }
}

Replace the following:

• VERSION: your cluster version, which must be GKE 1.20.6-gke.700 or later.
• CHANNEL_NAME: a release channel that includes GKE version 1.20.6-gke.700 or later.

This section shows you how to investigate and resolve issues with GKE Dataplane V2.

1. Confirm that GKE Dataplane V2 is enabled:

   kubectl -n kube-system get pods -l k8s-app=cilium -o wide
   

   If GKE Dataplane V2 is running, the output includes Pods with the prefix anetd-. anetd is the networking controller for GKE Dataplane V2.

2. If the issue is with services or network policy enforcement, check the anetd Pod logs. Use the following log selectors in Cloud Logging:

   resource.type="k8s_container"
   labels."k8s-pod/k8s-app"="cilium"
   resource.labels.cluster_name="CLUSTER_NAME"
   

3. If Pod creation is failing, check the kubelet logs for clues. Use the following log selectors in Cloud Logging:

   resource.type="k8s_node"
   log_name=~".*/logs/kubelet"
   resource.labels.cluster_name="CLUSTER_NAME"
   

   Replace CLUSTER_NAME with the name of the cluster, or remove it entirely to see logs for all clusters.

4. If the anetd Pods are not running, examine the cilium-config ConfigMap for any modifications. Avoid altering existing fields within this ConfigMap, because such changes can destabilize the cluster and disrupt anetd. The ConfigMap gets patched back to the default state only if new fields are added to it. Any changes to existing fields are not patched back, and we recommend not changing or customizing the ConfigMap.

In GKE Dataplane V2 clusters, intermittent connectivity problems can occur for masqueraded traffic or with ephemeral port usage. These problems are due to the potential port conflicts with the reserved NodePort range and typically happen in the following scenarios:

• Custom ip-masq-agent: If you use a custom ip-masq-agent (version 2.10 or later), where the cluster has NodePort or Load Balancer services, you might observe intermittent connectivity issues due to their conflict with the NodePort range. Since version 2.10 and later, ip-masq-agent has the --random-fully argument implemented internally by default. To mitigate this, explicitly set --random-fully=false (applicable since version 2.11) under arguments in your ip-masq-agent configuration. For configuration details, see Configuring an IP masquerade agent in Standard clusters.

• Ephemeral port range overlap: If the ephemeral port range that's defined by net.ipv4.ip_local_port_range on your GKE nodes overlaps with the NodePort range (30000-32767), it can also trigger connectivity issues. To prevent this problem, ensure that these two ranges don't overlap.

Review your ip-masq-agent configuration and ephemeral port range settings to ensure they don't conflict with the NodePort range. If you encounter intermittent connectivity issues, consider these potential causes and adjust your configuration accordingly.

Affected GKE versions: 1.29 and later

In clusters that use GKE Dataplane V2, you might encounter connectivity failures when traffic targets a node's IP:Port where port is the hostPort defined on the Pod. These issues arise in two primary scenarios:

• Nodes with hostPort behind a passthrough Network Load Balancer:

  hostPort ties a Pod to a specific node's port, and a passthrough Network Load Balancer distributes traffic across all nodes. When you expose Pods to the internet using hostPort and a passthrough Network Load Balancer, the load balancer might send traffic to a node where the Pod isn't running, causing connection failures. This is due to a known limitation in GKE Dataplane V2 where passthrough Network Load Balancer traffic is not consistently forwarded to hostPort Pods.

  Workaround: When exposing hostPorts of a Pod on the node with a passthrough Network Load Balancer, specify the internal or external IP address of the Network Load Balancer in the Pod's hostIP field.

  ports:
  - containerPort: 62000
    hostPort: 62000
    protocol: TCP
    hostIP: 35.232.62.64
  - containerPort: 60000
    hostPort: 60000
    protocol: TCP
    hostIP: 35.232.62.64
    # Assuming 35.232.62.64 is the external IP address of a passthrough Network Load Balancer.
  

• hostPort conflict with reserved NodePort range:

  If a Pod's hostPort conflicts with the reserved NodePort range (30000-32767), Cilium might fail to forward traffic to the Pod. This behavior has been observed in cluster versions 1.29 and later as Cilium now manages hostPort capabilites, replacing the previous Portmap method. This is an expected behavior for Cilium and is mentioned in their public documentation.

We don't plan to fix these limitations in later versions. The root cause of these issues is related to Cilium's behavior and outside the direct control of GKE.

Recommendation: We recommend that you migrate to NodePort Services instead of hostPort for improved reliability. NodePort Services provide similar capabilities.

If you specify an endPort field in a Network Policy on a cluster that has GKE Dataplane V2 enabled, it won't take effect.

Starting in GKE 1.22, the Kubernetes Network Policy API lets you specify a range of ports where the Network Policy is enforced. This API is supported in clusters with Calico Network Policy but is not supported in clusters with GKE Dataplane V2.

You can verify the behavior of your NetworkPolicy objects by reading them back after writing them to the API server. If the object still contains the endPort field, the feature is enforced. If the endPort field is missing, the feature is not enforced. In all cases, the object stored in the API server is the source of truth for the Network Policy.

For more information see KEP-2079: Network Policy to support Port Ranges.

Affected GKE versions: 1.22 to 1.25

GKE clusters running node pools that use containerd and have GKE Dataplane V2 enabled might experience IP address leak issues and exhaust all the Pod IP addresses on a node. A Pod scheduled on an affected node displays an error message similar to the following:

failed to allocate for range 0: no IP addresses available in range set: 10.48.131.1-10.48.131.62

For more information about the issue, see containerd issue #5768.

To fix this issue, upgrade your cluster to one of the following GKE versions:

• 1.22.17-gke.3100 or later.
• 1.23.16-gke.200 or later.
• 1.24.9-gke.3200 or later.
• 1.25.6-gke.200 or later.

You can mitigate this issue by deleting the leaked Pod IP addresses for the node.

To delete the leaked Pod IP addresses, get authentication credentials for the cluster and run the following steps to clean up a single node, if you know its name.

1. Save the following shell script to a file named cleanup.sh:

   for hash in $(sudo find /var/lib/cni/networks/gke-pod-network -iregex '/var/lib/cni/networks/gke-pod-network/[0-9].*' -exec head -n1 {} \;); do hash="${hash%%[[:space:]]}"; if [ -z $(sudo ctr -n k8s.io c ls | grep $hash | awk '{print $1}') ]; then sudo grep -ilr $hash /var/lib/cni/networks/gke-pod-network; fi; done | sudo xargs -r rm
   

2. Run the script on a cluster node:

   gcloud compute ssh --zone "ZONE" --project "PROJECT" NODE_NAME --command "$(cat cleanup.sh)"
   

   Replace NODE_NAME with the name of the node.

You can also run a DaemonSet version of this script to run in parallel on all nodes at once:

1. Save the following manifest to a file named cleanup-ips.yaml:

   apiVersion: apps/v1
   kind: DaemonSet
   metadata:
     name: cleanup-ipam-dir
     namespace: kube-system
   spec:
     selector:
       matchLabels:
         name: cleanup-ipam
     template:
       metadata:
         labels:
           name: cleanup-ipam
       spec:
         hostNetwork: true
         securityContext:
           runAsUser: 0
           runAsGroup: 0
         containers:
         - name: cleanup-ipam
           image: gcr.io/gke-networking-test-images/ubuntu-test:2022
           command:
             - /bin/bash
             - -c
             - |
               while true; do
               for hash in $(find /hostipam -iregex '/hostipam/[0-9].*' -mmin +10 -exec head -n1 {} \; ); do
               hash="${hash%%[[:space:]]}"
               if [ -z $(ctr -n k8s.io c ls | grep $hash | awk '{print $1}') ]; then
               grep -ilr $hash /hostipam
               fi
               done | xargs -r rm
               echo "Done cleaning up /var/lib/cni/networks/gke-pod-network at $(date)"
               sleep 120s
               done
           volumeMounts:
           - name: host-ipam
             mountPath: /hostipam
           - name: host-ctr
             mountPath: /run/containerd
         volumes:
         - name: host-ipam
           hostPath:
             path: /var/lib/cni/networks/gke-pod-network
         - name: host-ctr
           hostPath:
             path: /run/containerd
   

2. Run the daemonset on the cluster:

   kubectl apply -f cleanup-ips.yaml
   

   You must have kubectl access as an administrator of the cluster to run this command.

3. Check the logs of the running DaemonSet:

   kubectl -n kube-system logs -l name=cleanup-ipam
   

When a client Pod connects to itself using a Service or the virtual IP address of an internal passthrough Network Load Balancer, the reply packet is not identified as a part of an existing connection due to incorrect conntrack lookup in the dataplane. This means that a Network Policy that restricts ingress traffic for the Pod is incorrectly enforced on the packet.

The impact of this issue depends on the number of configured Pods for the Service. For example, if the Service has 1 backend Pod, the connection always fails. If the Service has 2 backend Pods, the connection fails 50% of the time.

To fix this issue, upgrade your cluster to one of the following GKE versions:

• 1.28.3-gke.1090000 or later.

You can mitigate this issue by configuring the port and containerPort in the Service manifest to be the same value.

When a Pod creates a TCP connection to itself using a Service, such that the Pod is both the source and destination of the connection, GKE Dataplane V2 eBPF connection tracking incorrectly tracks the connection states, leading to leaked conntrack entries.

When a connection tuple (protocol, source/destination IP, and source/destination port) has been leaked, new connections using the same connection tuple might result in return packets being dropped.

To fix this issue, upgrade your cluster to one of the following GKE versions:

• 1.28.3-gke.1090000 or later
• 1.27.11-gke.1097000 or later

Use one of the following workarounds:

• Enable TCP reuse (keep-alives) for applications running in Pods that might communicate with itself using a Service. This prevents the TCP FIN flag from being issued and avoid leaking the conntrack entry.

• When using short-lived connections, expose the Pod using a proxy load balancer, such as Gateway, to expose the Service. This results in the destination of the connection request being set to the load balancer IP address, preventing GKE Dataplane V2 from performing SNAT to the loopback IP address.

When you upgrade a GKE cluster that has GKE Dataplane V2 (advanced datapath) enabled from version 1.27 to 1.28, you might encounter a deadlock situation. Workloads might experience disruptions due to the inability to terminate old Pods or schedule necessary components like anetd.

The cluster upgrade process increases the resource requirement for the GKE Dataplane V2 components. This increase might lead to resource contention, which disrupts communication between the Cilium Container Network Interface (CNI) plugin and the Cilium daemon.

You might see the following symptoms:

• anetd Pods remain stuck in a Pending state.
• Workload Pods get stuck in a Terminating state.
• Errors indicating Cilium communication failures, such as failed to connect to Cilium daemon.

• Errors during network resource cleanup for Pod sandboxes, for example:

  1rpc error: code = Unknown desc = failed to destroy network for sandbox "[sandbox_id]": plugin type="cilium-cni" failed (delete): unable to connect to Cilium daemon... connection refused
  

Standard clusters: To resolve the issue and allow the anetd Pod to be scheduled, temporarily increase the allocatable resources on the affected node.

1. To identify the affected node and to check its allocatable CPU and memory, run the following command:

   kubectl get nodes $NODE_NAME -o json | jq '.status.allocatable | {cpu, memory}'
   

2. To temporarily increase the allocatable CPU and memory, run the following command:

   kubectl patch
   

Autopilot clusters: To resolve the deadlock issue on Autopilot clusters, free up resources by force deleting the affected Pod:

kubectl delete pod POD_NAME -n NAMESPACE --grace-period=0 --force

Replace the following:

• POD_NAME: the name of the Pod.
• NAMESPACE: the namespace of the Pod.

After you increase the allocatable resources on the node and when the upgrade from GKE version 1.27 to 1.28 completes, the anetd Pod runs on the newer version.

• Use network policy logging to record when connections to Pods are allowed or denied by your cluster's network policies.
• Learn how GKE Dataplane V2 works.

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