It is often important to isolate Dispatch builds and components onto dedicated node pools for security or performance reasons. This topic covers how to configure node pools in D2iQ’s Kubernetes distribution, Konvoy, to be used with Dispatch.

Pre-requisites

• A working Konvoy cluster

Setup Node Pools

In your Konvoy cluster.yaml, first add the pool to your nodePools list in the ClusterProvisioner object:

  - name: dispatch
    indexType: positional
    count: 10
    machine:
      rootVolumeSize: 80
      rootVolumeType: gp2
      imagefsVolumeEnabled: true
      imagefsVolumeSize: 160
      imagefsVolumeType: gp2
      imagefsVolumeDevice: xvdb
      type: m5.2xlarge

Set the count and type as necessary, then add labels and taints for the nodes to the nodePools list in the ClusterConfiguration object. A “taint” in Kubernetes is a restriction on a node to ensure that only pods with a particular “toleration” are scheduled onto it.

  - name: dispatch
    labels:
      - key: konvoy.mesosphere.com/node_pool
        value: dispatch
    taints:
      - key: konvoy.mesosphere.com/node_pool
        value: dispatch
        effect: NoExecute

The taint key and value can be anything you want, but it should be unique.

For a more detailed guide on configuring node pools in Konvoy, see the official Konvoy documentation.

Configure Dispatch

Next, Dispatch needs to be configured in the cluster.yaml to use tolerations when creating pods.

To schedule only the Dispatch tasks on the node pool, set the Tekton default pod template to use the tolerations:

    - configRepository: https://github.com/mesosphere/kubeaddons-dispatch
      configVersion: stable-1.16-1.3.0
      addonsList:
        - name: dispatch
          enabled: true
          values: |
            tekton:
              configs:
                defaultPodTemplate: |
                  tolerations:
                  - effect: NoExecute
                    key: konvoy.mesosphere.com/node_pool
                    value: dispatch
                    operator: Equal

However, you can configure all Dispatch components to use node pools:

    - configRepository: https://github.com/mesosphere/kubeaddons-dispatch
      configVersion: stable-1.16-1.3.0
      addonsList:
        - name: dispatch
          enabled: true
          values: |
            dispatch:
              tolerations:
              - effect: NoExecute
                key: konvoy.mesosphere.com/node_pool
                value: dispatch
                operator: Equal
            tekton-dashboard:
              tolerations:
              - effect: NoExecute
                key: konvoy.mesosphere.com/node_pool
                value: dispatch
                operator: Equal
            tekton:
              tolerations:
              - effect: NoExecute
                key: konvoy.mesosphere.com/node_pool
                value: dispatch
                operator: Equal
              configs:
                defaultPodTemplate: |
                  tolerations:
                  - effect: NoExecute
                    key: konvoy.mesosphere.com/node_pool
                    value: dispatch
                    operator: Equal

Deploy

To deploy your changes to your Konvoy cluster, run konvoy up.

Configure a custom node pool for a repository

It is also possible to configure tolerations for a specific repository.

Create a ConfigMap containing the pod template:

apiVersion: v1
kind: ConfigMap
metadata:
  name: repo-tolerations
data:
  template: |-
    tolerations:
    - effect: NoExecute
      key: konvoy.mesosphere.com/node_pool
      value: dispatch
      operator: Equal

And then create a repository using:

dispatch ci repository create --pod-template-config-map-name=repo-tolerations --pod-template-config-map-key=template

This will configure the new repository to use the specified tolerations.