Use Nomad "spread" Scheduler

README.md

Read Scheduler Config

curl -sS --header "X-Nomad-Token: $NOMAD_TOKEN" "$NOMAD_ADDR/v1/operator/scheduler/configuration" | jq .

Sample Output

{
  "SchedulerConfig": {
    "SchedulerAlgorithm": "binpack",
    "PreemptionConfig": {
      "SystemSchedulerEnabled": true,
      "BatchSchedulerEnabled": false,
      "ServiceSchedulerEnabled": false
    },
    "MemoryOversubscriptionEnabled": false,
    "CreateIndex": 5,
    "ModifyIndex": 5
  },
  "Index": 5,
  "LastContact": 0,
  "KnownLeader": true
}

Update Scheduler Config

Note: This also enables Memory Oversubscription.

curl -X POST --header "X-Nomad-Token: $NOMAD_TOKEN" "$NOMAD_ADDR/v1/operator/scheduler/configuration" --data \
'{
  "SchedulerAlgorithm": "spread",
  "MemoryOversubscriptionEnabled": true,
  "PreemptionConfig": {
    "SystemSchedulerEnabled": true,
    "BatchSchedulerEnabled": false,
    "ServiceSchedulerEnabled": false
  }
}'

Sample Output

{
  "SchedulerConfig": {
    "SchedulerAlgorithm": "spread",
    "PreemptionConfig": {
      "SystemSchedulerEnabled": true,
      "BatchSchedulerEnabled": false,
      "ServiceSchedulerEnabled": false
    },
    "MemoryOversubscriptionEnabled": true,
    "CreateIndex": 5,
    "ModifyIndex": 12335
  },
  "Index": 12335,
  "LastContact": 0,
  "KnownLeader": true
}

nomad added operator api command which can be used to interact with nomad api.

export NOMAD_ADDR=http://localhost:4646
export NOMAD_TOKEN=your-token

nomad operator api /v1/operator/scheduler/configuration | jq -c '.SchedulerConfig' | jq -c '.MemoryOversubscriptionEnabled=true' | nomad operator api -X POST /v1/operator/scheduler/configuration