Locality Load Balancing
This series of tasks demonstrate how to configure locality load balancing in Istio.
A locality defines the geographic location of a workload instance within your mesh. The following triplet defines a locality:
Region: Represents a large geographic area, such as us-east. A region typically contains a number of availability zones. In Kubernetes, the label
topology.kubernetes.io/regiondetermines a node’s region.
Zone: A set of compute resources within a region. By running services in multiple zones within a region, failover can occur between zones within the region while maintaining data locality with the end-user. In Kubernetes, the label
topology.kubernetes.io/zonedetermines a node’s zone.
Sub-zone: Allows administrators to further subdivide zones for more fine-grained control, such as “same rack”. The sub-zone concept doesn’t exist in Kubernetes. As a result, Istio introduced the custom node label
topology.istio.io/subzoneto define a sub-zone.
Localities are hierarchical, in the matching order:
That means that a pod running in zone
bar of region
is not considered to be local to a pod running in zone
bar of region
Istio uses this locality information to control load balancing behavior. Follow one of the tasks in this series to configure locality load balancing for your mesh.