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

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

[id="nodes-scheduler-default-modifying_{context}"]
= Modifying scheduler policies

//Made changes to this file to match https://github.com/openshift/openshift-docs/pull/13626/files#diff-ba6ab177a3e2867eaefe07f48bd6e158

You change scheduling behavior by creating or editing your scheduler policy ConfigMap in the `openshift-config` project.
Add and remove predicates and priorities to the ConfigMap to create a _scheduler policy_.


.Procedure

To modify the current custom scheduling, use one of the following methods:

* Edit the scheduler policy ConfigMap:
+
[source,terminal]
----
$ oc edit configmap <configmap-name>  -n openshift-config
----
+
For example:
+
[source,terminal]
----
$ oc edit configmap scheduler-policy -n openshift-config
----
+
.Example output
[source,yaml]
----
apiVersion: v1
data:
  policy.cfg: |
    {
        "kind" : "Policy",
        "apiVersion" : "v1",
        "predicates" : [ <1>
                {"name" : "MaxGCEPDVolumeCount"},
                {"name" : "GeneralPredicates"},
                {"name" : "MaxAzureDiskVolumeCount"},
                {"name" : "MaxCSIVolumeCountPred"},
                {"name" : "CheckVolumeBinding"},
                {"name" : "MaxEBSVolumeCount"},
                {"name" : "MatchInterPodAffinity"},
                {"name" : "CheckNodeUnschedulable"},
                {"name" : "NoDiskConflict"},
                {"name" : "NoVolumeZoneConflict"},
                {"name" : "PodToleratesNodeTaints"}
                ],
        "priorities" : [ <2>
                {"name" : "LeastRequestedPriority", "weight" : 1},
                {"name" : "BalancedResourceAllocation", "weight" : 1},
                {"name" : "ServiceSpreadingPriority", "weight" : 1},
                {"name" : "NodePreferAvoidPodsPriority", "weight" : 1},
                {"name" : "NodeAffinityPriority", "weight" : 1},
                {"name" : "TaintTolerationPriority", "weight" : 1},
                {"name" : "ImageLocalityPriority", "weight" : 1},
                {"name" : "SelectorSpreadPriority", "weight" : 1},
                {"name" : "InterPodAffinityPriority", "weight" : 1},
                {"name" : "EqualPriority", "weight" : 1}
                ]
    }
kind: ConfigMap
metadata:
  creationTimestamp: "2019-09-17T17:44:19Z"
  name: scheduler-policy
  namespace: openshift-config
  resourceVersion: "15370"
  selfLink: /api/v1/namespaces/openshift-config/configmaps/scheduler-policy
----
<1> Add or remove predicates as needed.
<2> Add, remove, or change the weight of predicates as needed.
+
It can take a few minutes for the scheduler to restart the pods with the updated policy.

* Change the policies and predicates being used:

. Remove the scheduler policy ConfigMap:
+
[source,terminal]
----
$ oc delete configmap -n openshift-config <name>
----
+
For example:
+
[source,terminal]
----
$ oc delete configmap -n openshift-config  scheduler-policy
----

. Edit the `policy.cfg` file to add and remove policies and predicates as needed.
+
For example:
+
[source,terminal]
----
$ vi policy.cfg
----
+
.Example output
[source,yaml]
----
apiVersion: v1
data:
  policy.cfg: |
    {
    "kind" : "Policy",
    "apiVersion" : "v1",
    "predicates" : [
            {"name" : "MaxGCEPDVolumeCount"},
            {"name" : "GeneralPredicates"},
            {"name" : "MaxAzureDiskVolumeCount"},
            {"name" : "MaxCSIVolumeCountPred"},
            {"name" : "CheckVolumeBinding"},
            {"name" : "MaxEBSVolumeCount"},
            {"name" : "MatchInterPodAffinity"},
            {"name" : "CheckNodeUnschedulable"},
            {"name" : "NoDiskConflict"},
            {"name" : "NoVolumeZoneConflict"},
            {"name" : "PodToleratesNodeTaints"}
            ],
    "priorities" : [
            {"name" : "LeastRequestedPriority", "weight" : 1},
            {"name" : "BalancedResourceAllocation", "weight" : 1},
            {"name" : "ServiceSpreadingPriority", "weight" : 1},
            {"name" : "NodePreferAvoidPodsPriority", "weight" : 1},
            {"name" : "NodeAffinityPriority", "weight" : 1},
            {"name" : "TaintTolerationPriority", "weight" : 1},
            {"name" : "ImageLocalityPriority", "weight" : 1},
            {"name" : "SelectorSpreadPriority", "weight" : 1},
            {"name" : "InterPodAffinityPriority", "weight" : 1},
            {"name" : "EqualPriority", "weight" : 1}
            ]
    }
----

. Re-create the scheduler policy ConfigMap based on the scheduler JSON file:
+
[source,terminal]
----
$ oc create configmap -n openshift-config --from-file=policy.cfg <configmap-name> <1>
----
<1> Enter a name for the ConfigMap.
+
For example:
+
[source,terminal]
----
$ oc create configmap -n openshift-config --from-file=policy.cfg scheduler-policy
----
+
.Example output
[source,terminal]
----
configmap/scheduler-policy created
----