fix: force default value for endpoint weight

  - in order to avoid having endpoint weight to 0, validation is done on service side and a protection is applied on gateway side

gravitee-apim-definition/gravitee-apim-definition-jackson/src/main/java/io/gravitee/definition/jackson/datatype/api/deser/EndpointDeserializer.java

@@ -72,6 +72,9 @@ public Endpoint deserialize(JsonParser parser, DeserializationContext ctxt) thro
         final JsonNode weightNode = node.get("weight");
         if (weightNode != null) {
             int weight = weightNode.asInt(Endpoint.DEFAULT_WEIGHT);
+            if (weight <= 0) {
+                weight = Endpoint.DEFAULT_WEIGHT;
+            }
             endpoint.setWeight(weight);
         } else {
             endpoint.setWeight(Endpoint.DEFAULT_WEIGHT);

gravitee-apim-definition/gravitee-apim-definition-model/src/main/java/io/gravitee/definition/model/v4/endpointgroup/Endpoint.java

@@ -48,7 +48,7 @@
 public class Endpoint implements Serializable {
 
     private static final long serialVersionUID = 7139083731513897591L;
-    private static final int DEFAULT_WEIGHT = 1;
+    public static final int DEFAULT_WEIGHT = 1;
 
     @NotBlank
     private String name;

gravitee-apim-gateway/gravitee-apim-gateway-core/src/main/java/io/gravitee/gateway/core/loadbalancer/WeightedLoadBalancer.java

@@ -48,10 +48,15 @@ private void loadRuntimeRatios() {
         int position = 0;
 
         for (Endpoint endpoint : endpoints) {
-            runtimeRatios.add(new WeightRatio(position++, endpoint.weight()));
+            runtimeRatios.add(new WeightRatio(position++, computeWeight(endpoint)));
         }
     }
 
+    private int computeWeight(final Endpoint endpoint) {
+        // has been implemented to protect the load balancer behavior as the initial weight cannot be 0 or lower
+        return endpoint.weight() > 0 ? endpoint.weight() : 1;
+    }
+
     boolean isRuntimeRatiosZeroed() {
         boolean cleared = true;
 

gravitee-apim-gateway/gravitee-apim-gateway-core/src/main/java/io/gravitee/gateway/reactive/core/v4/endpoint/loadbalancer/WeightedLoadBalancer.java

@@ -38,8 +38,14 @@ public void refresh() {
 
         int position = 0;
         for (ManagedEndpoint managedEndpoint : endpoints) {
-            computedDistribution.add(new WeightDistributions.WeightDistribution(position++, managedEndpoint.getDefinition().getWeight()));
+            computedDistribution.add(new WeightDistributions.WeightDistribution(position++, computeWeight(managedEndpoint)));
         }
         weightDistributions.set(new WeightDistributions(computedDistribution));
     }
+
+    private int computeWeight(final ManagedEndpoint managedEndpoint) {
+        // has been implemented to protect the load balancer behavior as the initial weight cannot be 0 or lower
+        int weight = managedEndpoint.getDefinition().getWeight();
+        return weight > 0 ? weight : 1;
+    }
 }

gravitee-apim-gateway/gravitee-apim-gateway-core/src/test/java/io/gravitee/gateway/core/loadbalancer/WeightedRoundRobinLoadBalancerTest.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright © 2015 The Gravitee team (http://gravitee.io)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.gravitee.gateway.core.loadbalancer;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import io.gravitee.gateway.api.endpoint.Endpoint;
+import io.gravitee.gateway.reactive.api.connector.endpoint.EndpointConnector;
+import io.gravitee.gateway.reactive.core.v4.endpoint.DefaultManagedEndpoint;
+import io.gravitee.gateway.reactive.core.v4.endpoint.DefaultManagedEndpointGroup;
+import io.gravitee.gateway.reactive.core.v4.endpoint.ManagedEndpoint;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.DisplayNameGeneration;
+import org.junit.jupiter.api.DisplayNameGenerator;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Guillaume LAMIRAND (guillaume.lamirand at graviteesource.com)
+ * @author GraviteeSource Team
+ */
+@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
+class WeightedRoundRobinLoadBalancerTest {
+
+    @Test
+    void should_return_null_with_empty_endpoints() {
+        WeightedRoundRobinLoadBalancer cut = new WeightedRoundRobinLoadBalancer(List.of());
+        Endpoint next = cut.next();
+        assertThat(next).isNull();
+    }
+
+    @Test
+    void should_return_endpoint_even_with_invalid_configured_weight() {
+        List<Endpoint> endpoints = new ArrayList<>();
+        Endpoint endpoint1 = endpoint(0);
+        endpoints.add(endpoint1);
+        WeightedRoundRobinLoadBalancer cut = new WeightedRoundRobinLoadBalancer(endpoints);
+        // 1
+        Endpoint next = cut.next();
+        assertThat(next).isEqualTo(endpoint1); // 1 > 0
+    }
+
+    @Test
+    void should_return_endpoints_in_order() {
+        List<Endpoint> endpoints = new ArrayList<>();
+        Endpoint endpoint1 = endpoint(1);
+        endpoints.add(endpoint1);
+        Endpoint endpoint2 = endpoint(5);
+        endpoints.add(endpoint2);
+        Endpoint endpoint3 = endpoint(3);
+        endpoints.add(endpoint3);
+
+        WeightedRoundRobinLoadBalancer cut = new WeightedRoundRobinLoadBalancer(endpoints);
+        // 1
+        Endpoint next = cut.next();
+        assertThat(next).isEqualTo(endpoint1); // 1 > 0
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint2); // 5 > 4
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint3); // 3 > 2
+
+        // 2
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint2); // 4 > 3
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint3); // 2 > 1
+
+        // 3
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint2); // 3 > 2
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint3); // 1 > 0
+
+        // 4
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint2); // 2 > 1
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint2); // 1 > 0
+
+        // 5
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint1);
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint2);
+        next = cut.next();
+        assertThat(next).isEqualTo(endpoint3);
+    }
+
+    private static Endpoint endpoint(int weight) {
+        Endpoint endpoint = mock(Endpoint.class, "endpoint with %s".formatted(weight));
+        when(endpoint.weight()).thenReturn(weight);
+        when(endpoint.primary()).thenReturn(true);
+        return endpoint;
+    }
+}

gravitee-apim-gateway/gravitee-apim-gateway-core/src/test/java/io/gravitee/gateway/reactive/core/v4/endpoint/loadbalancer/WeightedRoundRobinLoadBalancerTest.java

@@ -44,6 +44,23 @@ void should_return_null_with_empty_endpoints() {
         assertThat(next).isNull();
     }
 
+    @Test
+    void should_return_endpoint_even_with_invalid_configured_weight() {
+        List<ManagedEndpoint> endpoints = new ArrayList<>();
+        Endpoint endpoint1 = new Endpoint();
+        endpoint1.setWeight(0);
+        ManagedEndpoint managedEndpoint1 = new DefaultManagedEndpoint(
+            endpoint1,
+            new DefaultManagedEndpointGroup(new EndpointGroup()),
+            mock(EndpointConnector.class)
+        );
+        endpoints.add(managedEndpoint1);
+        WeightedRoundRobinLoadBalancer cut = new WeightedRoundRobinLoadBalancer(endpoints);
+        // 1
+        ManagedEndpoint next = cut.next();
+        assertThat(next).isEqualTo(managedEndpoint1); // 1 > 0
+    }
+
     @Test
     void should_return_endpoints_in_order() {
         List<ManagedEndpoint> endpoints = new ArrayList<>();

gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/main/java/io/gravitee/rest/api/service/v4/impl/validation/EndpointGroupsValidationServiceImpl.java

@@ -90,6 +90,7 @@ public List<EndpointGroup> validateAndSanitize(ApiType apiType, List<EndpointGro
                     .getEndpoints()
                     .forEach(endpoint -> {
                         validateUniqueEndpointName(endpoint.getName(), names);
+                        validateEndpointWeight(endpoint);
                         validateEndpointType(endpoint.getType());
                         validateServices(endpointGroup.getServices(), endpoint.getServices());
                         validateEndpointMatchType(endpointGroup, endpoint);
@@ -103,6 +104,12 @@ public List<EndpointGroup> validateAndSanitize(ApiType apiType, List<EndpointGro
         return endpointGroups;
     }
 
+    private void validateEndpointWeight(final Endpoint endpoint) {
+        if (endpoint.getWeight() <= 0) {
+            endpoint.setWeight(Endpoint.DEFAULT_WEIGHT);
+        }
+    }
+
     private void validateEndpointConfiguration(ConnectorPluginEntity endpointConnector, Endpoint endpoint) {
         endpoint.setConfiguration(endpointService.validateConnectorConfiguration(endpointConnector, endpoint.getConfiguration()));
     }

gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/test/java/io/gravitee/rest/api/service/v4/impl/validation/EndpointGroupsValidationServiceImplTest.java

@@ -149,6 +149,7 @@ public void shouldReturnValidatedEndpointGroupsWithEndpoints() {
         Endpoint validatedEndpoint = endpoints.get(0);
         assertThat(validatedEndpoint.getName()).isEqualTo("endpoint");
         assertThat(validatedEndpoint.getType()).isEqualTo("http");
+        assertThat(validatedEndpoint.getWeight()).isEqualTo(1);
         assertThat(validatedEndpointGroup.getServices()).isNotNull();
         assertThat(validatedEndpointGroup.getSharedConfiguration()).isNull();
         assertThat(validatedEndpointGroup.getLoadBalancer()).isNotNull();
@@ -185,6 +186,7 @@ public void shouldReturnValidatedEndpointGroupsWithGroupHealthChecks() {
         Endpoint validatedEndpoint = endpoints.get(0);
         assertThat(validatedEndpoint.getName()).isEqualTo("endpoint");
         assertThat(validatedEndpoint.getType()).isEqualTo("http");
+        assertThat(validatedEndpoint.getWeight()).isEqualTo(1);
         assertThat(validatedEndpointGroup.getServices())
             .isNotNull()
             .matches(svc -> svc.getHealthCheck().getConfiguration().equals(FIXED_HC_CONFIG));
@@ -457,6 +459,21 @@ public void shouldThrowValidationExceptionWithMismatch() {
             .isThrownBy(() -> endpointGroupsValidationService.validateAndSanitize(ApiType.PROXY, List.of(endpointGroup)));
     }
 
+    @Test
+    public void shouldReturnDefaultWeightWithWrongEndpointWeight() {
+        EndpointGroup endpointGroup = new EndpointGroup();
+        endpointGroup.setName("name");
+        endpointGroup.setType("http");
+        Endpoint endpoint = new Endpoint();
+        endpoint.setName("endpoint");
+        endpoint.setType("http");
+        endpoint.setWeight(0);
+        endpointGroup.setEndpoints(List.of(endpoint));
+        List<EndpointGroup> endpointGroups = endpointGroupsValidationService.validateAndSanitize(ApiType.PROXY, List.of(endpointGroup));
+
+        assertThat(endpointGroups.get(0).getEndpoints().get(0).getWeight()).isEqualTo(1);
+    }
+
     @Test(expected = EndpointMissingException.class)
     public void shouldThrowExceptionWithNullParameter() {
         assertThat(endpointGroupsValidationService.validateAndSanitize(ApiType.PROXY, null)).isNull();