Dual Pod Templates

LeaderWorkerSet supports defining distinct specifications for leader and worker pods within a replica.

Leader and Worker Templates

An LWS replica consists of one leader pod and N - 1 worker pods (where N is defined by .spec.leaderWorkerTemplate.size).

You can configure pod specifications using two template fields:

• workerTemplate (required): Defines the pod template for worker pods. If leaderTemplate is not specified, workerTemplate applies to the leader pod as well.
• leaderTemplate (optional): Defines a distinct pod template exclusively for the leader pod.

apiVersion: leaderworkerset.x-k8s.io/v1
kind: LeaderWorkerSet
metadata:
  name: leaderworkerset-sample
spec:
  replicas: 3
  leaderWorkerTemplate:
    size: 4
    leaderTemplate:
      spec:
        containers:
        - name: leader
          image: leader-coordinator:latest
          resources:
            requests:
              cpu: "2"
              memory: 4Gi
    workerTemplate:
      spec:
        containers:
        - name: worker
          image: worker-engine:latest
          resources:
            limits:
              nvidia.com/gpu: "8"

Common Use Cases

1. Heterogeneous Hardware: The leader pod can run as a coordinator, HTTP frontend, or driver on standard CPU nodes, while the worker pods run distributed model parallel computation on specialized GPU or TPU accelerator nodes.

2. Different Container Images or Configurations: The leader pod can run specialized tooling, telemetry sidecars, or API server processes that are not needed on worker pods.

3. Homogeneous Deployments: When leader and worker pods share the same container configuration, omit leaderTemplate and specify only workerTemplate. LWS will apply workerTemplate to all pods in the replica.