You can create a TCP/UDP Load Balancer by creating a
in its specification. This page explains the parameters you can use to
configure LoadBalancer Services. For more information specific to internal load
balancers, see Using an internal TCP/UDP load
balancer. For more
information specific to external load balancers, see Exposing applications
The following parameters are supported for Google Kubernetes Engine (GKE) LoadBalancer Services.
|Feature||Summary||Service Field||GKE Version Support|
|Local External Traffic Policy||Configures whether or not external traffic is load balanced across GKE nodes.||
|Load Balancer Source Ranges||Configures optional firewall rules in GKE and in the VPC to only allow certain source ranges.||
||All supported versions|
|Load Balancer IP||Specifies an IP for the load balancers||
||All supported versions|
|All-ports||The ability for the TCP/UDP load balancer to forward all ports instead of specific ports||N/A||No native support|
External traffic policy
externalTrafficPolicy is a standard Service option
that defines how and whether traffic incoming to a GKE node
is load balanced.
Cluster is the default policy but
Local is often used to
preserve the source IP of traffic coming into a cluster node.
effectively disables load balancing on the cluster node so that traffic that is
received by a local Pod sees the original source IP address.
externalTrafficPolicy is supported for internal LoadBalancer Services (via the
TCP/UDP load balancer), but load balancing behavior depends on where traffic
originates from and the configured traffic policy.
Traffic sourced from outside the cluster to a TCP/UDP load balancer will have the following behavior if there is at least one healthy Pod of the Service in the cluster:
Clusterpolicy: Traffic will be load balanced to any healthy GKE node in the cluster and then the kube-proxy will send it to a node with the Pod.
Localpolicy: Nodes that do not have one of the backend Pods appear as unhealthy to the TCP/UDP load balancer. Traffic will only be sent to one of the remaining healthy cluster nodes which has the Pod. Traffic is not routed again by the kube-proxy and instead will be sent directly to the local Pod with its IP header information intact.
If traffic to a given LoadBalancer Service IP is sourced from a GKE node inside the cluster, there is a different traffic behavior. The following table summarizes the traffic behavior for traffic sourced by a node or Pod inside the cluster destined for a member Pod of a LoadBalancer Service:
|externalTrafficPolicy||Service member Pod running on same node where traffic originates?||Traffic behavior|
|Cluster||Yes||Packets are delivered to any member Pod, either on the node or on a different node.|
|Cluster||No||Packets are delivered to any member Pod, which must be on a different node.|
|Local||Yes||Packets are delivered to any member Pod on the same node.|
Kubernetes 1.14 and earlier: Packets are dropped.
Kubernetes 1.15 and later: Packets are delivered to any member Pod, which must be on a different node.
Load balancer source ranges
spec: loadBalancerSourceRanges array specifies one or more internal IP
loadBalancerSourceRanges restricts traffic through the load
balancer to the IPs specified in this field. With this configuration,
creates the corresponding iptables rules in Kubernetes nodes.
GKE also creates a firewall rule in your VPC
network automatically. If you omit this field, your Service accepts traffic
from any IP address (
For more information about the Service specification, see the Service API reference.
Load balancer IP
spec: loadBalancerIP enables you to choose a specific IP address for the
load balancer. The IP address must not be in use by another internal TCP/UDP
load balancer or Service. If omitted, an ephemeral IP is assigned. For more
Reserving a static internal IP address.
If you create an internal TCP/UDP load balancer by using an annotated Service,
there is no way to set up a forwarding rule that uses all ports.
However, if you create an internal TCP/UDP load balancer manually, you can
choose your Google Kubernetes Engine nodes' instance group as the backend. Kubernetes
type: NodePort are available through the ILB.
- Read the GKE network overview.
- Learn more about Compute Engine load balancers.
- Learn about internal load balancers.
- Learn about exposing applications externally using services.