Fix infinite resource updates due to canonical format conversion of resource requirements

operator-framework-core/pom.xml

@@ -54,6 +54,11 @@
       <artifactId>junit-jupiter-engine</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-params</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/dependent/kubernetes/ResourceRequirementsSanitizer.java

@@ -0,0 +1,100 @@
+package io.javaoperatorsdk.operator.processing.dependent.kubernetes;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import io.fabric8.kubernetes.api.model.Container;
+import io.fabric8.kubernetes.api.model.GenericKubernetesResource;
+import io.fabric8.kubernetes.api.model.PodTemplateSpec;
+import io.fabric8.kubernetes.api.model.Quantity;
+import io.fabric8.kubernetes.api.model.ResourceRequirements;
+
+/**
+ * Sanitizes the {@link ResourceRequirements} in the containers of a pair of {@link PodTemplateSpec}
+ * instances.
+ * <p>
+ * When the sanitizer finds a mismatch in the structure of the given templates, before it gets to
+ * the nested resource limits and requests, it returns early without fixing the actual map. This is
+ * an optimization because the given templates will anyway differ at this point. This means we do
+ * not have to attempt to sanitize the resources for these use cases, since there will anyway be an
+ * update of the K8s resource.
+ * <p>
+ * The algorithm traverses the whole template structure because we need the actual and desired
+ * {@link Quantity} instances to compare their numerical amount. Using the
+ * {@link GenericKubernetesResource#get(Map, Object...)} shortcut would need to create new instances
+ * just for the sanitization check.
+ */
+class ResourceRequirementsSanitizer {
+
+  static void sanitizeResourceRequirements(final Map<String, Object> actualMap,
+      final PodTemplateSpec actualTemplate, final PodTemplateSpec desiredTemplate) {
+    if (actualTemplate == null || desiredTemplate == null) {
+      return;
+    }
+    if (actualTemplate.getSpec() == null || desiredTemplate.getSpec() == null) {
+      return;
+    }
+    sanitizeResourceRequirements(actualMap, actualTemplate.getSpec().getInitContainers(),
+        desiredTemplate.getSpec().getInitContainers(), "initContainers");
+    sanitizeResourceRequirements(actualMap, actualTemplate.getSpec().getContainers(),
+        desiredTemplate.getSpec().getContainers(), "containers");
+  }
+
+  private static void sanitizeResourceRequirements(final Map<String, Object> actualMap,
+      final List<Container> actualContainers, final List<Container> desiredContainers,
+      final String containerPath) {
+    int containers = desiredContainers.size();
+    if (containers == actualContainers.size()) {
+      for (int containerIndex = 0; containerIndex < containers; containerIndex++) {
+        var desiredContainer = desiredContainers.get(containerIndex);
+        var actualContainer = actualContainers.get(containerIndex);
+        if (!desiredContainer.getName().equals(actualContainer.getName())) {
+          return;
+        }
+        sanitizeResourceRequirements(actualMap, actualContainer.getResources(),
+            desiredContainer.getResources(),
+            containerPath, containerIndex);
+      }
+    }
+  }
+
+  private static void sanitizeResourceRequirements(final Map<String, Object> actualMap,
+      final ResourceRequirements actualResource, final ResourceRequirements desiredResource,
+      final String containerPath, final int containerIndex) {
+    if (desiredResource == null || actualResource == null) {
+      return;
+    }
+    sanitizeQuantities(actualMap, actualResource.getRequests(), desiredResource.getRequests(),
+        containerPath, containerIndex, "requests");
+    sanitizeQuantities(actualMap, actualResource.getLimits(), desiredResource.getLimits(),
+        containerPath, containerIndex, "limits");
+  }
+
+  @SuppressWarnings("unchecked")
+  private static void sanitizeQuantities(final Map<String, Object> actualMap,
+      final Map<String, Quantity> actualResource, final Map<String, Quantity> desiredResource,
+      final String containerPath, final int containerIndex, final String quantityPath) {
+    Optional.ofNullable(
+        GenericKubernetesResource.get(actualMap, "spec", "template", "spec", containerPath,
+            containerIndex, "resources", quantityPath))
+        .map(Map.class::cast)
+        .filter(m -> m.size() == desiredResource.size())
+        .ifPresent(m -> actualResource.forEach((key, actualQuantity) -> {
+          var desiredQuantity = desiredResource.get(key);
+          if (desiredQuantity == null) {
+            return;
+          }
+          // check if the string representation of the Quantity instances is equal
+          if (actualQuantity.getAmount().equals(desiredQuantity.getAmount())
+              && actualQuantity.getFormat().equals(desiredQuantity.getFormat())) {
+            return;
+          }
+          // check if the numerical amount of the Quantity instances is equal
+          if (actualQuantity.equals(desiredQuantity)) {
+            // replace the actual Quantity with the desired Quantity to prevent a resource update
+            m.replace(key, desiredQuantity.toString());
+          }
+        }));
+  }
+}