Merge pull request #410 from application-stacks/topology

Add Topology Spread Constraints support

api/v1/runtimecomponent_types.go

@@ -146,6 +146,20 @@ type RuntimeComponentSpec struct {
 	// Security context for the application container.
 	// +operator-sdk:csv:customresourcedefinitions:order=25,type=spec,displayName="Security Context"
 	SecurityContext *corev1.SecurityContext `json:"securityContext,omitempty"`
+
+	// +operator-sdk:csv:customresourcedefinitions:order=26,type=spec,displayName="Topology Spread Constraints"
+	TopologySpreadConstraints *RuntimeComponentTopologySpreadConstraints `json:"topologySpreadConstraints,omitempty"`
+}
+
+// Defines the topology spread constraints
+type RuntimeComponentTopologySpreadConstraints struct {
+	// The list of TopologySpreadConstraints for the application pod.
+	// +operator-sdk:csv:customresourcedefinitions:order=1,type=spec,displayName="Constraints"
+	Constraints *[]corev1.TopologySpreadConstraint `json:"constraints,omitempty"`
+
+	// Whether the operator should disable its default set of TopologySpreadConstraints. Defaults to false.
+	// +operator-sdk:csv:customresourcedefinitions:order=1,type=spec,displayName="Disable Operator Defaults",xDescriptors="urn:alm:descriptor:com.tectonic.ui:booleanSwitch"
+	DisableOperatorDefaults *bool `json:"disableOperatorDefaults,omitempty"`
 }
 
 // Defines the service account
@@ -917,6 +931,25 @@ func (cr *RuntimeComponent) GetSecurityContext() *corev1.SecurityContext {
 	return cr.Spec.SecurityContext
 }
 
+// GetTopologySpreadConstraints returns the pod topology spread constraints configuration
+func (cr *RuntimeComponent) GetTopologySpreadConstraints() common.BaseComponentTopologySpreadConstraints {
+	if cr.Spec.TopologySpreadConstraints == nil {
+		return nil
+	}
+	return cr.Spec.TopologySpreadConstraints
+}
+
+func (cr *RuntimeComponentTopologySpreadConstraints) GetConstraints() *[]corev1.TopologySpreadConstraint {
+	if cr.Constraints == nil {
+		return nil
+	}
+	return cr.Constraints
+}
+
+func (cr *RuntimeComponentTopologySpreadConstraints) GetDisableOperatorDefaults() *bool {
+	return cr.DisableOperatorDefaults
+}
+
 // Initialize the RuntimeComponent instance
 func (cr *RuntimeComponent) Initialize() {
 	if cr.Spec.PullPolicy == nil {

bundle/manifests/rc.app.stacks_runtimecomponents.yaml

@@ -5428,6 +5428,189 @@ spec:
                         type: string
                     type: object
                 type: object
+              topologySpreadConstraints:
+                description: Defines the topology spread constraints
+                properties:
+                  constraints:
+                    description: The list of TopologySpreadConstraints for the application
+                      pod.
+                    items:
+                      description: TopologySpreadConstraint specifies how to spread
+                        matching pods among the given topology.
+                      properties:
+                        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.
+                          properties:
+                            matchExpressions:
+                              description: matchExpressions is a list of label selector
+                                requirements. The requirements are ANDed.
+                              items:
+                                description: A label selector requirement is a selector
+                                  that contains values, a key, and an operator that
+                                  relates the key and values.
+                                properties:
+                                  key:
+                                    description: key is the label key that the selector
+                                      applies to.
+                                    type: string
+                                  operator:
+                                    description: operator represents a key's relationship
+                                      to a set of values. Valid operators are In,
+                                      NotIn, Exists and DoesNotExist.
+                                    type: string
+                                  values:
+                                    description: values is an array of string values.
+                                      If the operator is In or NotIn, the values array
+                                      must be non-empty. If the operator is Exists
+                                      or DoesNotExist, the values array must be empty.
+                                      This array is replaced during a strategic merge
+                                      patch.
+                                    items:
+                                      type: string
+                                    type: array
+                                required:
+                                - key
+                                - operator
+                                type: object
+                              type: array
+                            matchLabels:
+                              additionalProperties:
+                                type: string
+                              description: matchLabels is a map of {key,value} pairs.
+                                A single {key,value} in the matchLabels map is equivalent
+                                to an element of matchExpressions, whose key field
+                                is "key", the operator is "In", and the values array
+                                contains only "value". The requirements are ANDed.
+                              type: object
+                          type: object
+                          x-kubernetes-map-type: atomic
+                        matchLabelKeys:
+                          description: MatchLabelKeys is a set of pod label keys to
+                            select the pods over which spreading will be calculated.
+                            The keys are used to lookup values from the incoming pod
+                            labels, those key-value labels are ANDed with labelSelector
+                            to select the group of existing pods over which spreading
+                            will be calculated for the incoming pod. Keys that don't
+                            exist in the incoming pod labels will be ignored. A null
+                            or empty list means only match against labelSelector.
+                          items:
+                            type: string
+                          type: array
+                          x-kubernetes-list-type: atomic
+                        maxSkew:
+                          description: 'MaxSkew describes the degree to which pods
+                            may be unevenly distributed. When `whenUnsatisfiable=DoNotSchedule`,
+                            it is the maximum permitted difference between the number
+                            of matching pods in the target topology and the global
+                            minimum. The global minimum is the minimum number of matching
+                            pods in an eligible domain or zero if the number of eligible
+                            domains is less than MinDomains. For example, in a 3-zone
+                            cluster, MaxSkew is set to 1, and pods with the same labelSelector
+                            spread as 2/2/1: In this case, the global minimum is 1.
+                            | zone1 | zone2 | zone3 | |  P P  |  P P  |   P   | -
+                            if MaxSkew is 1, incoming pod can only be scheduled to
+                            zone3 to become 2/2/2; scheduling it onto zone1(zone2)
+                            would make the ActualSkew(3-1) on zone1(zone2) violate
+                            MaxSkew(1). - if MaxSkew is 2, incoming pod can be scheduled
+                            onto any zone. When `whenUnsatisfiable=ScheduleAnyway`,
+                            it is used to give higher precedence to topologies that
+                            satisfy it. It''s a required field. Default value is 1
+                            and 0 is not allowed.'
+                          format: int32
+                          type: integer
+                        minDomains:
+                          description: "MinDomains indicates a minimum number of eligible
+                            domains. When the number of eligible domains with matching
+                            topology keys is less than minDomains, Pod Topology Spread
+                            treats \"global minimum\" as 0, and then the calculation
+                            of Skew is performed. And when the number of eligible
+                            domains with matching topology keys equals or greater
+                            than minDomains, this value has no effect on scheduling.
+                            As a result, when the number of eligible domains is less
+                            than minDomains, scheduler won't schedule more than maxSkew
+                            Pods to those domains. If value is nil, the constraint
+                            behaves as if MinDomains is equal to 1. Valid values are
+                            integers greater than 0. When value is not nil, WhenUnsatisfiable
+                            must be DoNotSchedule. \n For example, in a 3-zone cluster,
+                            MaxSkew is set to 2, MinDomains is set to 5 and pods with
+                            the same labelSelector spread as 2/2/2: | zone1 | zone2
+                            | zone3 | |  P P  |  P P  |  P P  | The number of domains
+                            is less than 5(MinDomains), so \"global minimum\" is treated
+                            as 0. In this situation, new pod with the same labelSelector
+                            cannot be scheduled, because computed skew will be 3(3
+                            - 0) if new Pod is scheduled to any of the three zones,
+                            it will violate MaxSkew. \n This is a beta field and requires
+                            the MinDomainsInPodTopologySpread feature gate to be enabled
+                            (enabled by default)."
+                          format: int32
+                          type: integer
+                        nodeAffinityPolicy:
+                          description: "NodeAffinityPolicy indicates how we will treat
+                            Pod's nodeAffinity/nodeSelector when calculating pod topology
+                            spread skew. Options are: - Honor: only nodes matching
+                            nodeAffinity/nodeSelector are included in the calculations.
+                            - Ignore: nodeAffinity/nodeSelector are ignored. All nodes
+                            are included in the calculations. \n If this value is
+                            nil, the behavior is equivalent to the Honor policy. This
+                            is a alpha-level feature enabled by the NodeInclusionPolicyInPodTopologySpread
+                            feature flag."
+                          type: string
+                        nodeTaintsPolicy:
+                          description: "NodeTaintsPolicy indicates how we will treat
+                            node taints when calculating pod topology spread skew.
+                            Options are: - Honor: nodes without taints, along with
+                            tainted nodes for which the incoming pod has a toleration,
+                            are included. - Ignore: node taints are ignored. All nodes
+                            are included. \n If this value is nil, the behavior is
+                            equivalent to the Ignore policy. This is a alpha-level
+                            feature enabled by the NodeInclusionPolicyInPodTopologySpread
+                            feature flag."
+                          type: string
+                        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. We define a domain as a particular
+                            instance of a topology. Also, we define an eligible domain
+                            as a domain whose nodes meet the requirements of nodeAffinityPolicy
+                            and nodeTaintsPolicy. e.g. If TopologyKey is "kubernetes.io/hostname",
+                            each Node is a domain of that topology. And, if TopologyKey
+                            is "topology.kubernetes.io/zone", each zone is a domain
+                            of that topology. It's a required field.
+                          type: string
+                        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 schedule the
+                            pod in any location, but giving higher precedence to topologies
+                            that would help reduce the skew. A constraint is considered
+                            "Unsatisfiable" for an incoming pod if and only if every
+                            possible node assignment for that pod would violate "MaxSkew"
+                            on some topology. 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
+                      required:
+                      - maxSkew
+                      - topologyKey
+                      - whenUnsatisfiable
+                      type: object
+                    type: array
+                  disableOperatorDefaults:
+                    description: Whether the operator should disable its default set
+                      of TopologySpreadConstraints. Defaults to false.
+                    type: boolean
+                type: object
               volumeMounts:
                 description: Represents where to mount the volumes into the application
                   container.

bundle/manifests/runtime-component.clusterserviceversion.yaml

@@ -71,7 +71,7 @@ metadata:
     categories: Application Runtime
     certified: "true"
     containerImage: icr.io/appcafe/runtime-component-operator:daily
-    createdAt: "2023-10-27T14:38:16Z"
+    createdAt: "2023-11-01T20:37:23Z"
     description: Deploys any runtime component with dynamic and auto-tuning configuration
     olm.skipRange: '>=0.8.0 <1.3.0'
     operators.openshift.io/infrastructure-features: '["disconnected"]'
@@ -142,6 +142,15 @@ spec:
         path: serviceAccount.mountToken
         x-descriptors:
         - urn:alm:descriptor:com.tectonic.ui:booleanSwitch
+      - description: The list of TopologySpreadConstraints for the application pod.
+        displayName: Constraints
+        path: topologySpreadConstraints.constraints
+      - description: Whether the operator should disable its default set of TopologySpreadConstraints.
+          Defaults to false.
+        displayName: Disable Operator Defaults
+        path: topologySpreadConstraints.disableOperatorDefaults
+        x-descriptors:
+        - urn:alm:descriptor:com.tectonic.ui:booleanSwitch
       - description: Name of the application. Defaults to the name of this custom
           resource.
         displayName: Application Name
@@ -347,6 +356,8 @@ spec:
         path: statefulSet.storage.className
         x-descriptors:
         - urn:alm:descriptor:com.tectonic.ui:text
+      - displayName: Topology Spread Constraints
+        path: topologySpreadConstraints
       - description: The directory inside the container where this persisted storage
           will be bound to.
         displayName: Storage Mount Path

common/types.go

@@ -190,6 +190,11 @@ type BaseComponentServiceAccount interface {
 	GetName() *string
 }
 
+type BaseComponentTopologySpreadConstraints interface {
+	GetConstraints() *[]corev1.TopologySpreadConstraint
+	GetDisableOperatorDefaults() *bool
+}
+
 // BaseComponent represents basic kubernetes application
 type BaseComponent interface {
 	GetApplicationImage() string
@@ -222,6 +227,7 @@ type BaseComponent interface {
 	GetGroupName() string
 	GetRoute() BaseComponentRoute
 	GetAffinity() BaseComponentAffinity
+	GetTopologySpreadConstraints() BaseComponentTopologySpreadConstraints
 	GetSecurityContext() *corev1.SecurityContext
 	GetManageTLS() *bool
 }