openshift-docs/modules/nodes-scheduler-default-sample.adoc

// Module included in the following assemblies:
//
// * nodes/nodes-scheduler-default.adoc

[id="nodes-scheduler-default-sample_{context}"]
= Sample Policy Configurations

The configuration below specifies the default scheduler configuration, if it
were to be specified using the scheduler policy file.

[source,yaml]
----
{
"kind": "Policy",
"apiVersion": "v1",
"predicates": [
    {
        "name": "RegionZoneAffinity", <1>
        "argument": {
            "serviceAffinity": {  <2>
              "labels": ["region, zone"]  <3>
           }
        }
     }
  ],
"priorities": [
    {
        "name":"RackSpread", <4>
        "weight" : 1,
        "argument": {
            "serviceAntiAffinity": {  <5>
                "label": "rack"  <6>
                }
           }
       }
   ]
}
----

<1> The name for the predicate.
<2> The type of predicate.
<3> The labels for the predicate.
<4> The name for the priority.
<5> The type of priority.
<6> The labels for the priority.


In all of the sample configurations below, the list of predicates and priority
functions is truncated to include only the ones that pertain to the use case
specified.  In practice, a complete/meaningful scheduler policy should include
most, if not all, of the default predicates and priorities listed above.

The following example defines three topological levels, region (affinity) -> zone (affinity) -> rack (anti-affinity):

[source,yaml]
----
{
"kind": "Policy",
"apiVersion": "v1",
"predicates": [
    {
        "name": "RegionZoneAffinity",
        "argument": {
            "serviceAffinity": {
              "labels": ["region, zone"]
           }
        }
     }
  ],
"priorities": [
    {
        "name":"RackSpread",
        "weight" : 1,
        "argument": {
            "serviceAntiAffinity": {
                "label": "rack"
                }
           }
       }
   ]
}
----


The following example defines three topological levels, city (affinity) -> building
(anti-affinity) -> room (anti-affinity):

[source,yaml]
----
{
"kind": "Policy",
"apiVersion": "v1",
"predicates": [
    {
        "name": "CityAffinity",
        "argument": {
            "serviceAffinity": {
              "label": "city"
           }
        }
     }
  ],
"priorities": [
    {
        "name":"BuildingSpread",
        "weight" : 1,
        "argument": {
            "serviceAntiAffinity": {
                "label": "building"
                }
           }
       },
    {
        "name":"RoomSpread",
        "weight" : 1,
        "argument": {
            "serviceAntiAffinity": {
                "label": "room"
                }
           }
       }
   ]
}
----

The following example defines a policy to only use nodes with the 'region' label defined and prefer nodes with the 'zone'
label defined:

[source,yaml]
----
{
"kind": "Policy",
"apiVersion": "v1",
"predicates": [
    {
        "name": "RequireRegion",
        "argument": {
            "labelPreference": {
                "labels": ["region"],
                "presence": true
           }
        }
     }
  ],
"priorities": [
    {
        "name":"ZonePreferred",
        "weight" : 1,
        "argument": {
            "labelPreference": {
                "label": "zone",
                "presence": true
                }
           }
       }
   ]
}
----

The following example combines both static and configurable predicates and
also priorities:

[source,yaml]
----
{
"kind": "Policy",
"apiVersion": "v1",
"predicates": [
    {
        "name": "RegionAffinity",
        "argument": {
            "serviceAffinity": {
                "labels": ["region"]
           }
        }
     },
    {
        "name": "RequireRegion",
        "argument": {
            "labelsPresence": {
                "labels": ["region"],
                "presence": true
           }
        }
     },
    {
        "name": "BuildingNodesAvoid",
        "argument": {
            "labelsPresence": {
                "label": "building",
                "presence": false
           }
        }
     },
     {"name" : "PodFitsPorts"},
     {"name" : "MatchNodeSelector"}
     ],
"priorities": [
    {
        "name": "ZoneSpread",
        "weight" : 2,
        "argument": {
            "serviceAntiAffinity":{
                "label": "zone"
                }
           }
       },
    {
        "name":"ZonePreferred",
        "weight" : 1,
        "argument": {
            "labelPreference":{
                "label": "zone",
                "presence": true
                }
           }
       },
    {"name" : "ServiceSpreadingPriority", "weight" : 1}
    ]
}
----