Allow setting nomad resource limits for waypoint server pre_task

[Zarickan]

Is your feature request related to a problem? Please describe.
The pre_task for the waypoint server and runner jobs default to 200 MHz CPU and 600 MB memory, without option of specifying their values. This means that I am unable to run waypoint on my small/resource constrained nomad cluster as waypoint would required 2*600 MB for the pre_task parts of both the runner and server jobs.

It is unexpected that the resources required for the server and runner respectively are actually 600 MB + x and 200 MHz + y when specifying x and y as the memory and CPU values.

Describe the solution you'd like
Ability to configure the resources for the pre_task part of the waypoint server job when running waypoint install the same way it can be configured for the server and runner jobs with e.g. -nomad-server-cpu and -nomad-server-memory

Describe alternatives you've considered
Increasing capacity of workers in the nomad cluster.

Explain any additional use-cases
n/a

Additional context
As far as I can tell from the code all the pre_task does is run chown on a folder:

waypoint/internal/installutil/nomad/nomad.go

Lines 231 to 254 in e97cd4a

	func SetupPretask(volumeMounts []*api.VolumeMount) *api.Task {
	preTask := api.NewTask("pre_task", "docker")
	// Observed WP user and group IDs in the published container, update if those ever change
	waypointUserID := 100
	waypointGroupID := 1000
	cpu := DefaultResourcesCPU
	mem := DefaultResourcesMemory
	preTask.Config = map[string]interface{}{
	// Doing this because this is the only way https://github.com/hashicorp/nomad/issues/8892
	"image": "busybox:latest",
	"command": "sh",
	"args": []string{"-c", fmt.Sprintf("chown -R %d:%d /data/", waypointUserID, waypointGroupID)},
	}
	preTask.VolumeMounts = volumeMounts
	preTask.Resources = &api.Resources{
	CPU: &cpu,
	MemoryMB: &mem,
	}
	preTask.Lifecycle = &api.TaskLifecycle{
	Hook: "prestart",
	Sidecar: false,
	}
	return preTask
	}

waypoint/internal/installutil/nomad/nomad.go

Lines 16 to 23 in e97cd4a

	const (
	// bytes
	DefaultCSIVolumeCapacityMin = int64(1073741824)
	DefaultCSIVolumeCapacityMax = int64(2147483648)
	DefaultCSIVolumeMountFS = "xfs"
	DefaultResourcesCPU = 200
	DefaultResourcesMemory = 600
	)

This seems like a lot of resources to allocate in the pre_task to something so simple.

[evanphx]

Hi @Zarickan! Great find, totally agree those limits are wrong for the pretask. We'll update the pretask to use far, far smaller limits because it just needs to run a couple of unix commands anyway.