feat: allow reconcilers to override their configuration at runtime

If a reconciler implements `ConfigurableReconciler`, then QOSDK will
derive a new configuration for the reconciler by calling
`updateConfigurationFrom` before registering the reconciler with this
new configuration.

(cherry picked from commit 5b354c0)

Author: metacosm

core/runtime/src/main/java/io/quarkiverse/operatorsdk/runtime/OperatorProducer.java

@@ -12,7 +12,10 @@
 
 import io.fabric8.kubernetes.api.model.HasMetadata;
 import io.javaoperatorsdk.operator.Operator;
+import io.javaoperatorsdk.operator.api.config.ControllerConfiguration;
+import io.javaoperatorsdk.operator.api.config.ControllerConfigurationOverrider;
 import io.javaoperatorsdk.operator.api.reconciler.Reconciler;
+import io.quarkiverse.operatorsdk.runtime.api.ConfigurableReconciler;
 import io.quarkus.arc.DefaultBean;
 
 @Singleton
@@ -30,6 +33,7 @@ public class OperatorProducer {
      * @param reconcilers the detected {@link Reconciler} implementations
      * @return a properly configured {@link Operator} instance
      */
+    @SuppressWarnings({ "rawtypes", "unchecked" })
     @Produces
     @DefaultBean
     @ApplicationScoped
@@ -48,7 +52,14 @@ Operator operator(QuarkusConfigurationService configuration, Instance<Reconciler
 
         Operator operator = new Operator(configuration);
         for (Reconciler<? extends HasMetadata> reconciler : reconcilers) {
-            operator.register(reconciler);
+            if (reconciler instanceof ConfigurableReconciler configurable) {
+                ControllerConfiguration conf = configuration.getConfigurationFor(reconciler);
+                final var override = ControllerConfigurationOverrider.override(conf);
+                conf = configurable.updateConfigurationFrom(override);
+                operator.register(reconciler, conf);
+            } else {
+                operator.register(reconciler);
+            }
         }
 
         // if we set a termination timeout, install a shutdown hook

core/runtime/src/main/java/io/quarkiverse/operatorsdk/runtime/api/ConfigurableReconciler.java

@@ -0,0 +1,29 @@
+package io.quarkiverse.operatorsdk.runtime.api;
+
+import io.fabric8.kubernetes.api.model.HasMetadata;
+import io.javaoperatorsdk.operator.api.config.ConfigurationService;
+import io.javaoperatorsdk.operator.api.config.ControllerConfiguration;
+import io.javaoperatorsdk.operator.api.config.ControllerConfigurationOverrider;
+import io.javaoperatorsdk.operator.api.reconciler.Reconciler;
+
+/**
+ * Implement to change a {@link io.javaoperatorsdk.operator.api.reconciler.Reconciler}'s
+ * configuration at runtime
+ *
+ * @param <P> the primary resource type of the reconciler
+ * @since 7.2
+ */
+public interface ConfigurableReconciler<P extends HasMetadata> {
+    /**
+     * Updates the reconciler's configuration by applying the modifications specified by the provided
+     * {@link ControllerConfigurationOverrider} and then replacing the existing configuration in the
+     * {@link ConfigurationService} for this reconciler. Note that this method will not be applied if
+     * there is no configuration (as determined by {@link
+     * ConfigurationService#getConfigurationFor(Reconciler)} for the reconciler.
+     *
+     * @param configOverrider provides the modifications to apply to the existing reconciler's
+     *        configuration
+     * @return the updated {@link ControllerConfiguration} to use to register the associated {@link Reconciler}
+     */
+    ControllerConfiguration<P> updateConfigurationFrom(ControllerConfigurationOverrider<P> configOverrider);
+}