CLD-925: Topology Spread Constraints Implementation Changes Commit(#168)

Co-authored-by: Sumanth Ravipati <[email protected]>

Author: sumanthravipati

charts/values.yaml

@@ -94,29 +94,24 @@ license:
 
 ## Configure Affinity property for scheduling pods to nodes
 ## ref: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity
-## Preferred anti affinity rule to schedule one marklogic pod per worker node
-affinity: 
-  podAntiAffinity:
-    preferredDuringSchedulingIgnoredDuringExecution:
-    - weight: 100
-      podAffinityTerm:
-        labelSelector:
-          matchExpressions:
-          - key: app.kubernetes.io/name
-            operator: In
-            values:
-            - marklogic
-        topologyKey: kubernetes.io/hostname
-
-## Configure POD Topology Spread Constraints to spread Pods across cluster
+affinity: {}
+
+## Configure POD Topology Spread Constraints to spread pods across cluster
 ## ref: https://kubernetes.io/docs/concepts/scheduling-eviction/topology-spread-constraints/
-topologySpreadConstraints: []
-  # - maxSkew: 1
-  #   topologyKey: topology.kubernetes.io/zone
-  #   whenUnsatisfiable: ScheduleAnyway
-  #   labelSelector:
-  #     matchLabels:
-  #       app.kubernetes.io/name: marklogic
+## Preferred Topology Spread Constraints rule to evenly distribute Marklogic pods across worker nodes and zones
+topologySpreadConstraints:
+  - maxSkew: 1
+    topologyKey: kubernetes.io/hostname
+    whenUnsatisfiable: DoNotSchedule
+    labelSelector:
+      matchLabels:
+        app.kubernetes.io/name: marklogic
+  - maxSkew: 1
+    topologyKey: topology.kubernetes.io/zone
+    whenUnsatisfiable: ScheduleAnyway
+    labelSelector:
+      matchLabels:
+        app.kubernetes.io/name: marklogic
 
 ## Configure NodeSelector property for scheduling pods to nodes
 ## ref: https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes/#create-a-pod-that-gets-scheduled-to-your-chosen-node

test/template/pod_antiaffinity_templ_test.go

@@ -0,0 +1,78 @@
+package template_test
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	appsv1 "k8s.io/api/apps/v1"
+
+	"github.com/gruntwork-io/terratest/modules/helm"
+	"github.com/gruntwork-io/terratest/modules/k8s"
+	"github.com/gruntwork-io/terratest/modules/random"
+)
+
+func TestChartTemplateTopologySpreadConstraintClass(t *testing.T) {
+
+	// Path to the helm chart we will test
+	helmChartPath, err := filepath.Abs("../../charts")
+	releaseName := "marklogic-topologyspreadconstraint-test"
+	t.Log(helmChartPath, releaseName)
+	require.NoError(t, err)
+
+	// Set up the namespace; confirm that the template renders the expected value for the namespace.
+	namespaceName := "marklogic-" + strings.ToLower(random.UniqueId())
+	t.Logf("Namespace: %s\n", namespaceName)
+
+	// Setup the args for helm install
+	options := &helm.Options{
+		SetValues: map[string]string{
+			"image.repository":    "marklogicdb/marklogic-db",
+			"image.tag":           "latest",
+			"persistence.enabled": "false",
+		},
+		KubectlOptions: k8s.NewKubectlOptions("", "", namespaceName),
+	}
+
+	// render the tempate
+	output := helm.RenderTemplate(t, options, helmChartPath, releaseName, []string{"templates/statefulset.yaml"})
+
+	var statefulset appsv1.StatefulSet
+	helm.UnmarshalK8SYaml(t, output, &statefulset)
+
+	// Verify the name and namespace matches
+	require.Equal(t, namespaceName, statefulset.Namespace)
+
+	// Verify the topologySpreadConstraint rule is set
+	expectedLabelSelector := map[string]string{
+		"app.kubernetes.io/name": "marklogic",
+	}
+	expectedMaxSkewValue := 1
+	expectedHostTopologyKey := "kubernetes.io/hostname"
+	expectedHostScheduleCondition := "DoNotSchedule"
+	expectedZoneTopologyKey := "topology.kubernetes.io/zone"
+	expectedZoneScheduleCondition := "ScheduleAnyway"
+
+	topologySpreadConstraintsRule := statefulset.Spec.Template.Spec.TopologySpreadConstraints
+
+	hostMaxSkew := int(topologySpreadConstraintsRule[0].MaxSkew)
+	hostTopologyKey := topologySpreadConstraintsRule[0].TopologyKey
+	hostScheduleCondition := topologySpreadConstraintsRule[0].WhenUnsatisfiable
+	hostLabelSelector := topologySpreadConstraintsRule[0].LabelSelector.MatchLabels
+
+	zoneMaxSkew := int(topologySpreadConstraintsRule[1].MaxSkew)
+	zoneTopologyKey := topologySpreadConstraintsRule[1].TopologyKey
+	zoneScheduleCondition := topologySpreadConstraintsRule[1].WhenUnsatisfiable
+	zoneLabelSelector := topologySpreadConstraintsRule[1].LabelSelector.MatchLabels
+
+	require.Equal(t, hostMaxSkew, expectedMaxSkewValue)
+	require.Equal(t, hostTopologyKey, expectedHostTopologyKey)
+	require.Equal(t, string(hostScheduleCondition), expectedHostScheduleCondition)
+	require.Equal(t, hostLabelSelector, expectedLabelSelector)
+
+	require.Equal(t, zoneMaxSkew, expectedMaxSkewValue)
+	require.Equal(t, zoneTopologyKey, expectedZoneTopologyKey)
+	require.Equal(t, string(zoneScheduleCondition), expectedZoneScheduleCondition)
+	require.Equal(t, zoneLabelSelector, expectedLabelSelector)
+}