OWLS-80960 - Allow replicas count to drop below min dynamic cluster size

docs/domains/Domain.json

@@ -109,6 +109,10 @@
           "description": "The name of this cluster. Required",
           "type": "string"
         },
+        "allowReplicasBelowMinDynClusterSize": {
+          "description": "If true (the default), then the number of replicas is allowed to drop below the minimum dynamic cluster size configured in the WebLogic domain home configuration. Otherwise, the operator will ensure that the number of replicas is not less than the minimum dynamic cluster setting. This setting applies to dynamic clusters only.",
+          "type": "boolean"
+        },
         "serverPod": {
           "description": "Configuration affecting server pods.",
           "$ref": "#/definitions/ServerPod"

docs/domains/Domain.md

@@ -77,6 +77,7 @@ An element representing a cluster in the domain configuration.
 
 | Name | Type | Description |
 | --- | --- | --- |
+| `allowReplicasBelowMinDynClusterSize` | Boolean | If true (the default), then the number of replicas is allowed to drop below the minimum dynamic cluster size configured in the WebLogic domain home configuration. Otherwise, the operator will ensure that the number of replicas is not less than the minimum dynamic cluster setting. This setting applies to dynamic clusters only. |
 | `clusterName` | string | The name of this cluster. Required |
 | `clusterService` | [Kubernetes Resource](#kubernetes-resource) | Customization affecting ClusterIP Kubernetes services for the WebLogic cluster. |
 | `maxUnavailable` | number | The maximum number of cluster members that can be temporarily unavailable. Defaults to 1. |

docs/domains/index.html

@@ -1029,6 +1029,10 @@
           "description": "The name of this cluster. Required",
           "type": "string"
         },
+        "allowReplicasBelowMinDynClusterSize": {
+          "description": "If true (the default), then the number of replicas is allowed to drop below the minimum dynamic cluster size configured in the WebLogic domain home configuration. Otherwise, the operator will ensure that the number of replicas is not less than the minimum dynamic cluster setting. This setting applies to dynamic clusters only.",
+          "type": "boolean"
+        },
         "serverPod": {
           "description": "Configuration affecting server pods.",
           "$ref": "#/definitions/ServerPod"

kubernetes/crd/domain-crd.yaml

@@ -5478,6 +5478,14 @@ spec:
                     clusterName:
                       description: The name of this cluster. Required
                       type: string
+                    allowReplicasBelowMinDynClusterSize:
+                      description: If true (the default), then the number of replicas
+                        is allowed to drop below the minimum dynamic cluster size
+                        configured in the WebLogic domain home configuration. Otherwise,
+                        the operator will ensure that the number of replicas is not
+                        less than the minimum dynamic cluster setting. This setting
+                        applies to dynamic clusters only.
+                      type: boolean
                     serverPod:
                       description: Configuration affecting server pods.
                       type: object

kubernetes/crd/domain-v1beta1-crd.yaml

@@ -5367,6 +5367,14 @@ spec:
                   clusterName:
                     description: The name of this cluster. Required
                     type: string
+                  allowReplicasBelowMinDynClusterSize:
+                    description: If true (the default), then the number of replicas
+                      is allowed to drop below the minimum dynamic cluster size configured
+                      in the WebLogic domain home configuration. Otherwise, the operator
+                      will ensure that the number of replicas is not less than the
+                      minimum dynamic cluster setting. This setting applies to dynamic
+                      clusters only.
+                    type: boolean
                   serverPod:
                     description: Configuration affecting server pods.
                     type: object

operator/src/main/java/oracle/kubernetes/operator/KubernetesConstants.java

@@ -25,6 +25,7 @@ public interface KubernetesConstants {
 
   boolean DEFAULT_HTTP_ACCESS_LOG_IN_LOG_HOME = true;
   boolean DEFAULT_INCLUDE_SERVER_OUT_IN_POD_LOG = true;
+  boolean DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE = true;
 
   String CONTAINER_NAME = "weblogic-server";
 

operator/src/main/java/oracle/kubernetes/operator/steps/ManagedServersUpStep.java

@@ -246,10 +246,11 @@ private void logIfReplicasLessThanClusterServersMin(WlsClusterConfig clusterConf
     private boolean lessThanMinConfiguredClusterSize(WlsClusterConfig clusterConfig) {
       if (clusterConfig != null) {
         String clusterName = clusterConfig.getClusterName();
-        int configMinClusterSize
-                = clusterConfig.getMinDynamicClusterSize();
-        return clusterConfig.hasDynamicServers()
-                && domain.getReplicaCount(clusterName) < configMinClusterSize;
+        if (clusterConfig.hasDynamicServers()
+            && !domain.isAllowReplicasBelowMinDynClusterSize(clusterName)) {
+          int configMinClusterSize = clusterConfig.getMinDynamicClusterSize();
+          return domain.getReplicaCount(clusterName) < configMinClusterSize;
+        }
       }
       return false;
     }

operator/src/main/java/oracle/kubernetes/weblogic/domain/ClusterConfigurator.java

@@ -128,4 +128,6 @@ ClusterConfigurator withLivenessProbeSettings(
   ClusterConfigurator withToleration(V1Toleration toleration);
 
   ClusterConfigurator withPrecreateServerService(boolean precreateServerService);
+
+  ClusterConfigurator withAllowReplicasBelowDynClusterSize(boolean allowReplicasBelowDynClusterSize);
 }

operator/src/main/java/oracle/kubernetes/weblogic/domain/EffectiveConfigurationFactory.java

@@ -30,4 +30,6 @@ public interface EffectiveConfigurationFactory {
   boolean isShuttingDown();
 
   List<String> getAdminServerChannelNames();
+
+  boolean isAllowReplicasBelowMinDynClusterSize(String clusterName);
 }

operator/src/main/java/oracle/kubernetes/weblogic/domain/model/Cluster.java

@@ -4,6 +4,7 @@
 package oracle.kubernetes.weblogic.domain.model;
 
 import java.util.Map;
+import java.util.Optional;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
@@ -12,6 +13,7 @@
 import oracle.kubernetes.json.Description;
 import oracle.kubernetes.json.EnumClass;
 import oracle.kubernetes.json.Range;
+import oracle.kubernetes.operator.KubernetesConstants;
 import oracle.kubernetes.operator.ServerStartPolicy;
 import org.apache.commons.lang3.builder.EqualsBuilder;
 import org.apache.commons.lang3.builder.HashCodeBuilder;
@@ -57,6 +59,15 @@ public class Cluster extends BaseConfiguration implements Comparable<Cluster> {
   @Expose
   private KubernetesResource clusterService = new KubernetesResource();
 
+  /** Whether to allow the number of replicas to drop below the minimum dynamic cluster
+   *  size configured in the WebLogic domain home configuration. Default is true. */
+  @Description("If true (the default), then the number of replicas is allowed to drop below the "
+      + "minimum dynamic cluster size configured in the WebLogic domain home configuration. "
+      + "Otherwise, the operator will ensure that the number of replicas is not less than "
+      + "the minimum dynamic cluster setting. This setting applies to dynamic clusters only."
+  )
+  private Boolean allowReplicasBelowMinDynClusterSize;
+
   protected Cluster getConfiguration() {
     Cluster configuration = new Cluster();
     configuration.fillInFrom(this);
@@ -85,6 +96,22 @@ public void setReplicas(Integer replicas) {
     this.replicas = replicas;
   }
 
+  /**
+   * Whether to allow number of replicas to drop below the minimum dynamic cluster size configured
+   * in the WebLogic domain home configuration.
+   *
+   * @return whether to allow number of replicas to drop below the minimum dynamic cluster size
+   *     configured in the WebLogic domain home configuration.
+   */
+  public boolean isAllowReplicasBelowMinDynClusterSize() {
+    return Optional.ofNullable(allowReplicasBelowMinDynClusterSize)
+        .orElse(KubernetesConstants.DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE);
+  }
+
+  public void setAllowReplicasBelowMinDynClusterSize(boolean value) {
+    allowReplicasBelowMinDynClusterSize = value;
+  }
+
   @Nullable
   @Override
   public String getServerStartPolicy() {
@@ -145,6 +172,7 @@ public String toString() {
         .append("serverStartPolicy", serverStartPolicy)
         .append("clusterService", clusterService)
         .append("maxUnavailable", maxUnavailable)
+        .append("allowReplicasBelowMinDynClusterSize", allowReplicasBelowMinDynClusterSize)
         .toString();
   }
 
@@ -167,6 +195,7 @@ public boolean equals(Object o) {
         .append(serverStartPolicy, cluster.serverStartPolicy)
         .append(clusterService, cluster.clusterService)
         .append(maxUnavailable, cluster.maxUnavailable)
+        .append(allowReplicasBelowMinDynClusterSize, cluster.allowReplicasBelowMinDynClusterSize)
         .isEquals();
   }
 
@@ -179,6 +208,7 @@ public int hashCode() {
         .append(serverStartPolicy)
         .append(clusterService)
         .append(maxUnavailable)
+        .append(allowReplicasBelowMinDynClusterSize)
         .toHashCode();
   }
 

operator/src/main/java/oracle/kubernetes/weblogic/domain/model/Domain.java

@@ -297,6 +297,19 @@ public int getMinAvailable(String clusterName) {
     return Math.max(getReplicaCount(clusterName) - getMaxUnavailable(clusterName), 0);
   }
 
+  /**
+   * Returns whether the specified cluster is allowed to have replica count below the minimum
+   * dynamic cluster size configured in WebLogic domain configuration.
+   *
+   * @param clusterName the name of the cluster
+   * @return whether the specified cluster is allowed to have replica count below the minimum
+   *     dynamic cluster size configured in WebLogic domain configuration
+   */
+  public boolean isAllowReplicasBelowMinDynClusterSize(String clusterName) {
+    return getEffectiveConfigurationFactory().isAllowReplicasBelowMinDynClusterSize(clusterName);
+  }
+
+
   /**
    * DomainSpec is a description of a domain.
    *

operator/src/main/java/oracle/kubernetes/weblogic/domain/model/DomainCommonConfigurator.java

@@ -707,6 +707,12 @@ public ClusterConfigurator withNodeName(String nodeName) {
       return this;
     }
 
+    @Override
+    public ClusterConfigurator withAllowReplicasBelowDynClusterSize(boolean allowReplicasBelowDynClusterSize) {
+      cluster.setAllowReplicasBelowMinDynClusterSize(allowReplicasBelowDynClusterSize);
+      return this;
+    }
+
     @Override
     public ClusterConfigurator withSchedulerName(String schedulerName) {
       getDomainSpec().setSchedulerName(schedulerName);

operator/src/main/java/oracle/kubernetes/weblogic/domain/model/DomainSpec.java

@@ -842,6 +842,10 @@ private boolean hasMaxUnavailable(Cluster cluster) {
     return cluster != null && cluster.getMaxUnavailable() != null;
   }
 
+  private boolean isAllowReplicasBelowDynClusterSizeFor(Cluster cluster) {
+    return cluster.isAllowReplicasBelowMinDynClusterSize();
+  }
+
   public AdminServer getAdminServer() {
     return adminServer;
   }
@@ -907,6 +911,11 @@ public List<String> getAdminServerChannelNames() {
       return adminServer != null ? adminServer.getChannelNames() : Collections.emptyList();
     }
 
+    @Override
+    public boolean isAllowReplicasBelowMinDynClusterSize(String clusterName) {
+      return isAllowReplicasBelowDynClusterSizeFor(getCluster(clusterName));
+    }
+
     private Cluster getOrCreateCluster(String clusterName) {
       Cluster cluster = getCluster(clusterName);
       if (cluster != null) {

operator/src/test/java/oracle/kubernetes/operator/steps/ManagedServersUpStepTest.java

@@ -159,6 +159,15 @@ private void addWlsCluster(String clusterName, String... serverNames) {
     configSupport.addWlsCluster(clusterName, serverNames);
   }
 
+  private void addDynamicWlsCluster(String clusterName,
+      int minDynamicClusterSize,
+      int maxDynamicClusterSize,
+      String... serverNames) {
+    configSupport.addDynamicWlsCluster(clusterName, serverNames);
+    configSupport.getWlsCluster(clusterName).getDynamicServersConfig().setMinDynamicClusterSize(minDynamicClusterSize);
+    configSupport.getWlsCluster(clusterName).getDynamicServersConfig().setMaxDynamicClusterSize(maxDynamicClusterSize);
+  }
+
   @Test
   public void whenStartPolicyUndefined_startServers() {
     invokeStepWithConfiguredServer();
@@ -541,6 +550,44 @@ public void whenClusterStartupDefinedWithPreCreateServerService_allServersDown_a
     assertThat(getServers(), empty());
   }
 
+  @Test
+  public void whenReplicasLessThanMinDynClusterSize_setReplicaCountToMinClusterSize() {
+    startNoServers();
+    setCluster1Replicas(0);
+    setCluster1AllowReplicasBelowMinDynClusterSize(false);
+
+    addDynamicWlsCluster("cluster1", 2, 5,"ms1", "ms2", "ms3", "ms4", "ms5");
+
+    invokeStep();
+
+    assertThat(2, equalTo(domain.getReplicaCount("cluster1")));
+  }
+
+  @Test
+  public void whenReplicasLessThanMinDynClusterSize_allowBelowMin_doNotChangeReplicaCount() {
+    startNoServers();
+    setCluster1Replicas(0);
+
+    addDynamicWlsCluster("cluster1", 2, 5,"ms1", "ms2", "ms3", "ms4", "ms5");
+
+    invokeStep();
+
+    assertThat(0, equalTo(domain.getReplicaCount("cluster1")));
+  }
+
+  @Test
+  public void whenReplicasMoreThanMinDynClusterSize_doNotChangeReplicaCount() {
+    startNoServers();
+    setCluster1Replicas(3);
+    setCluster1AllowReplicasBelowMinDynClusterSize(false);
+
+    addDynamicWlsCluster("cluster1", 2, 5,"ms1", "ms2", "ms3", "ms4", "ms5");
+
+    invokeStep();
+
+    assertThat(3, equalTo(domain.getReplicaCount("cluster1")));
+  }
+
   private void assertStoppingServers(Step step, String... servers) {
     assertThat(((ServerDownIteratorStep) step).getServersToStop(), containsInAnyOrder(servers));
   }
@@ -569,7 +616,11 @@ private void setDefaultReplicas(int replicas) {
   }
 
   private void setCluster1Replicas(int replicas) {
-    configureCluster("cluster1").withReplicas(replicas);
+    configurator.configureCluster("cluster1").withReplicas(replicas);
+  }
+
+  private void setCluster1AllowReplicasBelowMinDynClusterSize(boolean allowReplicasBelowMinDynClusterSize) {
+    configurator.configureCluster("cluster1").withAllowReplicasBelowDynClusterSize(allowReplicasBelowMinDynClusterSize);
   }
 
   private void configureServers(String... serverNames) {

operator/src/test/java/oracle/kubernetes/weblogic/domain/DomainTestBase.java

@@ -20,6 +20,7 @@
 import org.junit.Test;
 
 import static oracle.kubernetes.operator.KubernetesConstants.ALWAYS_IMAGEPULLPOLICY;
+import static oracle.kubernetes.operator.KubernetesConstants.DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE;
 import static oracle.kubernetes.operator.KubernetesConstants.DEFAULT_IMAGE;
 import static oracle.kubernetes.operator.KubernetesConstants.IFNOTPRESENT_IMAGEPULLPOLICY;
 import static oracle.kubernetes.operator.KubernetesConstants.LATEST_IMAGE_SUFFIX;
@@ -28,7 +29,7 @@
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasItem;
-import static org.junit.Assert.assertThat;
+import static org.hamcrest.junit.MatcherAssert.assertThat;
 
 public abstract class DomainTestBase {
   protected static final String CLUSTER_NAME = "cluster1";
@@ -318,6 +319,21 @@ public void afterMaxUnavailableSetForCluster_canReadIt() {
     assertThat(domain.getMaxUnavailable("cluster1"), equalTo(5));
   }
 
+  @Test
+  public void afterAllowReplicasBelowMinDynamicClusterSizeSetForCluster_canReadIt() {
+    configureCluster("cluster1").withAllowReplicasBelowDynClusterSize(false);
+
+    assertThat(domain.isAllowReplicasBelowMinDynClusterSize("cluster1"), equalTo(false));
+  }
+
+  @Test
+  public void whenNotSpecified_allowReplicasBelowMinDynamicClusterSizeHasDefault() {
+    configureCluster("cluster1");
+
+    assertThat(domain.isAllowReplicasBelowMinDynClusterSize("cluster1"),
+        equalTo(DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE));
+  }
+
   @Test
   public void whenBothClusterAndServerStateSpecified_managedServerUsesServerState() {
     configureServer(SERVER1).withDesiredState("STAND-BY");