Background

We really like using resource_classes from #668 to be able to vary CPU/memory requests based off a single agent template, but currently if a pipeline step doesn't specify a resource_class: foo, they don't get any resource requests at all. I was hoping perhaps specifying resources in pod-spec-patch would be the fallback/default in that case, but pod-spec-patch's resources override anything from resource_class:

applyResourceClass happens around 524:

and then later on the pod-spec-patch and plugin spec patches are applied on top:

it'd be nice to have a default that applies when a step doesn't remember to specify a resource_class

Changes

Adds a new default-resource-class-name config option that references a named resource class from resource-classes. When a job doesn't have a resource_class agent tag, the default kicks in; jobs that explicitly set resource_class still take priority.

usage looks like:

resource-classes:
  small:
    resource:
      requests:
        cpu: "500m"
        memory: "512Mi"
  large:
    resource:
      requests:
        cpu: "2"
        memory: "4Gi"

default-resource-class-name: "small"

I also added resource-classes to the helm schema since it seemed to be missing?

Testing

• Unit tests for applyResourceClass covering the various combinations (no tag/no default, tag specified, default fallback, tag overrides default, error cases)
• Integration test that verifies the default resource class actually gets applied by checking cgroup limits