topologyspreadconstraint.json

{
  "description": "TopologySpreadConstraint specifies how to spread matching pods among the given topology.",
  "properties": {
    "labelSelector": {
      "$ref": "https://kubernetesjsonschema.dev/v1.18.1/_definitions.json#/definitions/io.k8s.apimachinery.pkg.apis.meta.v1.LabelSelector",
      "description": "LabelSelector is used to find matching pods. Pods that match this label selector are counted to determine the number of pods in their corresponding topology domain."
    },
    "maxSkew": {
      "description": "MaxSkew describes the degree to which pods may be unevenly distributed. It's the maximum permitted difference between the number of matching pods in any two topology domains of a given topology type. For example, in a 3-zone cluster, MaxSkew is set to 1, and pods with the same labelSelector spread as 1/1/0: | zone1 | zone2 | zone3 | |   P   |   P   |       | - if MaxSkew is 1, incoming pod can only be scheduled to zone3 to become 1/1/1; scheduling it onto zone1(zone2) would make the ActualSkew(2-0) on zone1(zone2) violate MaxSkew(1). - if MaxSkew is 2, incoming pod can be scheduled onto any zone. It's a required field. Default value is 1 and 0 is not allowed.",
      "format": "int32",
      "type": [
        "integer",
        "null"
      ]
    },
    "topologyKey": {
      "description": "TopologyKey is the key of node labels. Nodes that have a label with this key and identical values are considered to be in the same topology. We consider each <key, value> as a \"bucket\", and try to put balanced number of pods into each bucket. It's a required field.",
      "type": [
        "string",
        "null"
      ]
    },
    "whenUnsatisfiable": {
      "description": "WhenUnsatisfiable indicates how to deal with a pod if it doesn't satisfy the spread constraint. - DoNotSchedule (default) tells the scheduler not to schedule it - ScheduleAnyway tells the scheduler to still schedule it It's considered as \"Unsatisfiable\" if and only if placing incoming pod on any topology violates \"MaxSkew\". For example, in a 3-zone cluster, MaxSkew is set to 1, and pods with the same labelSelector spread as 3/1/1: | zone1 | zone2 | zone3 | | P P P |   P   |   P   | If WhenUnsatisfiable is set to DoNotSchedule, incoming pod can only be scheduled to zone2(zone3) to become 3/2/1(3/1/2) as ActualSkew(2-1) on zone2(zone3) satisfies MaxSkew(1). In other words, the cluster can still be imbalanced, but scheduler won't make it *more* imbalanced. It's a required field.",
      "type": [
        "string",
        "null"
      ]
    }
  },
  "required": [
    "maxSkew",
    "topologyKey",
    "whenUnsatisfiable"
  ],
  "type": "object",
  "$schema": "http://json-schema.org/schema#"
}