This approach deploys a separate scheduler alongside the default Kubernetes scheduler. This is useful in environments where you don't have access to modify the default scheduler configuration, such as Amazon EKS.

In this setup, a new scheduler (``my-scheduler``) is deployed with the Neuron Scheduler Extension integrated. Pods that need to run Neuron workloads specify this custom scheduler in their configuration.

.. note::

    Amazon EKS does not natively support modifying the default scheduler, so this multiple scheduler approach is required for EKS environments.

**Prerequisites**

Ensure that the Neuron Device Plugin is running.

**Step 1: Install Neuron Scheduler Extension**

Install the Neuron Scheduler Extension as a custom scheduler:

.. code:: bash

    helm upgrade --install neuron-helm-chart oci://public.ecr.aws/neuron/neuron-helm-chart \
        --set "scheduler.enabled=true" \
        --set "npd.enabled=false"

**Step 2: Verify Installation**

Check that there are no errors in the ``my-scheduler`` pod logs and that the ``k8s-neuron-scheduler`` pod is bound to a node:

.. code:: bash

    kubectl logs -n kube-system my-scheduler-79bd4cb788-hq2sq

**Expected output:**

.. code:: bash

    I1012 15:30:21.629611       1 scheduler.go:604] "Successfully bound pod to node" pod="kube-system/k8s-neuron-scheduler-5d9d9d7988-xcpqm" node="ip-192-168-2-25.ec2.internal" evaluatedNodes=1 feasibleNodes=1

**Step 3: Configure Pods to Use Custom Scheduler**

When creating Pods that need to use the Neuron Scheduler Extension, specify ``my-scheduler`` as the scheduler name. Here's a sample Pod specification:

.. code:: yaml

    apiVersion: v1
    kind: Pod
    metadata:
      name: <POD_NAME>
    spec:
      restartPolicy: Never
      schedulerName: my-scheduler
      containers:
        - name: <POD_NAME>
          command: ["<COMMAND>"]
          image: <IMAGE_NAME>
          resources:
            limits:
              cpu: "4"
              memory: 4Gi
              aws.amazon.com/neuroncore: 9
            requests:
              cpu: "1"
              memory: 1Gi

**Step 4: Verify Scheduling**

After running a Neuron workload Pod, verify that the Neuron Scheduler successfully processed the filter and bind requests:

.. code:: bash

    kubectl logs -n kube-system k8s-neuron-scheduler-5d9d9d7988-xcpqm

**Expected output for filter request:**

.. code:: bash

    2022/10/12 15:41:16 POD nrt-test-5038 fits in Node:ip-192-168-2-25.ec2.internal
    2022/10/12 15:41:16 Filtered nodes: [ip-192-168-2-25.ec2.internal]
    2022/10/12 15:41:16 Failed nodes: map[]
    2022/10/12 15:41:16 Finished Processing Filter Request...

**Expected output for bind request:**

.. code:: bash

    2022/10/12 15:41:16 Executing Bind Request!
    2022/10/12 15:41:16 Determine if the pod %v is NeuronDevice podnrt-test-5038
    2022/10/12 15:41:16 Updating POD Annotation with alloc devices!
    2022/10/12 15:41:16 Return aws.amazon.com/neuroncore
    2022/10/12 15:41:16 neuronDevUsageMap for resource:aws.amazon.com/neuroncore in node: ip-192-168-2-25.ec2.internal is [false false false false false false false false false false false false false false false false]
    2022/10/12 15:41:16 Allocated ids for POD nrt-test-5038 are: 0,1,2,3,4,5,6,7,8
    2022/10/12 15:41:16 Try to bind pod nrt-test-5038 in default namespace to node ip-192-168-2-25.ec2.internal with &Binding{ObjectMeta:{nrt-test-5038    8da590b1-30bc-4335-b7e7-fe574f4f5538  0 0001-01-01 00:00:00 +0000 UTC <nil> <nil> map[] map[] [] []  []},Target:ObjectReference{Kind:Node,Namespace:,Name:ip-192-168-2-25.ec2.internal,UID:,APIVersion:,ResourceVersion:,FieldPath:,},}
    2022/10/12 15:41:16 Updating the DevUsageMap since the bind is successful!
    2022/10/12 15:41:16 Return aws.amazon.com/neuroncore
    2022/10/12 15:41:16 neuronDevUsageMap for resource:aws.amazon.com/neuroncore in node: ip-192-168-2-25.ec2.internal is [false false false false false false false false false false false false false false false false]
    2022/10/12 15:41:16 neuronDevUsageMap for resource:aws.amazon.com/neurondevice in node: ip-192-168-2-25.ec2.internal is [false false false false]
    2022/10/12 15:41:16 Allocated devices list 0,1,2,3,4,5,6,7,8 for resource aws.amazon.com/neuroncore
    2022/10/12 15:41:16 Allocated devices list [0] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [0] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [0] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [0] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [1] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [1] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [1] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [1] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Allocated devices list [2] for other resource aws.amazon.com/neurondevice
    2022/10/12 15:41:16 Return aws.amazon.com/neuroncore
    2022/10/12 15:41:16 Succesfully updated the DevUsageMap [true true true true true true true true true false false false false false false false]  and otherDevUsageMap [true true true false] after alloc for node ip-192-168-2-25.ec2.internal
    2022/10/12 15:41:16 Finished executing Bind Request...