GKE networking known issues

NEG Controller stops managing endpoints when port removed from Service

When the NEG controller is configured to create a Standalone NEG for a Service and one of the configured ports is later removed from the Service, the NEG controller will eventually stop managing endpoints for the NEG. In addition to Services where the user creates a Standalone NEG annotation, this also affects Services which are referenced by GKE Gateway, MCI, and GKE Multi Cluster Gateway.

Workaround:

When removing a port from a Service with a Standalone NEG annotation, the annotation needs to also be updated to remove the port in question.

Gateway TLS configuration error

We've identified an issue with configuring TLS for Gateways in clusters running GKE version 1.28.4-gke.1083000. This affects TLS configurations using either an SSLCertificate or a CertificateMap. If you're upgrading a cluster with existing Gateways, updates made to the Gateway will fail. For new Gateways, the load balancers won't be provisioned. This issue will be fixed in an upcoming GKE 1.28 patch version.

• 1.26.13-gke.1052000 and later
• 1.27.10-gke.1055000 and later
• 1.28.6-gke.1095000 and later
• 1.29.1-gke.1016000 and later

Intermittent connection establishment failures

Clusters on control plane versions 1.26.6-gke.1900 and later might encounter intermittent connection establishment failures.

The chances of failures are low and it doesn't affect all clusters. The failures should stop completely after a few days since the symptom onset.

• 1.27.11-gke.1118000 or later
• 1.28.7-gke.1100000 or later
• 1.29.2-gke.1217000 or later

DNS resolution issues with Container-Optimized OS

Workloads running on GKE clusters with Container-Optimized OS-based nodes might experience DNS resolution issues.

Network Policy drops a connection due to incorrect connection tracking lookup

For clusters with GKE Dataplane V2 enabled, 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.

Workaround:

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

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

Packet drops for hairpin connection flows

For clusters with GKE Dataplane V2 enabled, 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.

Workaround:

Use one of the following workarounds:

• Enable TCP reuse (keep-alives) for an application running in a Pod that might communicate with itself using a Service. This prevents the TCP FIN flag from being issued and avoids 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.

Device typed network in GKE multi-network fails with long network names

Cluster creation fails with the following error:

error starting very-long-string-that-exceeds-character-limit-gpu-nic0 device plugin endpoint: listen unix /var/lib/kubelet/plugins_registry/networking.gke.io.networks_very-long-string-that-exceeds-character-limit-gpu-nic0.sock: bind: invalid argument

Workaround:

Limit the length of device-typed network object names to 41 characters or less. The full path of each UNIX domain socket is composed, including the corresponding network name. Linux has a limitation on socket path lengths (under 107 bytes). After accounting for the directory, filename prefix, and the .sock extension, the network name is limited to a maximum of 41 characters.

• 1.30.4-gke.1282000 or later
• 1.29.8-gke.1157000 or later
• 1.28.13-gke.1078000 or later
• 1.27.16-gke.1342000 or later

Connectivity issues for hostPort Pods after control plane upgrade

Clusters with network policy enabled might experience connectivity issues with hostPort Pods. Additionally, newly created Pods might take an additional 30 to 60 seconds to be ready.

The issue is triggered when the GKE control plane of a cluster is upgraded to one of the following GKE versions

• 1.30 to 1.30.4-gke.1281999
• 1.29.1-gke.1545000 to 1.29.8-gke.1156999
• 1.28.7-gke.1042000 to 1.28.13-gke.1077999
• 1.27.12-gke.1107000 to 1.27.16-gke.1341999

Workaround:

Upgrade or recreate nodes immediately after the GKE control plane upgrade.

Calico Pods not healthy on clusters with less than 3 total nodes and insufficient vCPU

Calico-typha and calico-node Pods can't be scheduled on clusters meeting all of the following conditions: fewer than 3 nodes total, each node having 1 or fewer allocatable vCPUs, and network policy enabled enabled. This is due to insufficient CPU resources.

Workarounds:

• Scale to a minimum of 3 node pools with 1 node using 1 allocatable vCPU.
• Resize a single node pool to a minimum of 3 nodes with 1 allocatable vCPU.
• Use a machine-type with at least 2 allocatable vCPU on a node pool with a single node.