docs: blog about 5.3.0 release

Signed-off-by: Attila Mészáros <a_meszaros@apple.com>

Author: csviri

docs/content/en/blog/releases/v5-3-release.md

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+---
+title: Version 5.3 Released!
+date: 2026-03-07
+author: >-
+  [Attila Mészáros](https://github.com/csviri)
+---
+
+We're pleased to announce the release of Java Operator SDK v5.3.0! This minor version brings
+two headline features — read-cache-after-write consistency and a new metrics implementation —
+along with a configuration adapter system, MDC improvements, and a number of smaller improvements
+and cleanups.
+
+## Key Features
+
+### Read-cache-after-write Consistency and Event Filtering
+
+This is the headline feature of 5.3. Informer caches are inherently eventually consistent: after
+your reconciler updates a resource, there is a window of time before the change is visible in the
+cache. This can cause subtle bugs, particularly when storing allocated values in the status
+sub-resource and reading them back in the next reconciliation.
+
+From 5.3.0, the framework provides two guarantees when you use
+[`ResourceOperations`](https://github.com/operator-framework/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/ResourceOperations.java)
+(accessible from `Context`):
+
+1. **Read-after-write**: Reading from the cache after your update — even within the same
+   reconciliation — returns at least the version of the resource from your update response.
+2. **Event filtering**: Events produced by your own writes no longer trigger a redundant
+   reconciliation.
+
+`UpdateControl` and `ErrorStatusUpdateControl` use this automatically. Secondary resources benefit
+via `context.resourceOperations()`:
+
+```java
+public UpdateControl<WebPage> reconcile(WebPage webPage, Context<WebPage> context) {
+
+    ConfigMap managedConfigMap = prepareConfigMap(webPage);
+    // update is cached and will suppress the resulting event
+    context.resourceOperations().serverSideApply(managedConfigMap);
+
+    // fresh resource instantly available from the cache
+    var upToDateResource = context.getSecondaryResource(ConfigMap.class);
+
+    makeStatusChanges(webPage);
+    // UpdateControl also uses this by default
+    return UpdateControl.patchStatus(webPage);
+}
+```
+
+If your reconciler relied on being re-triggered by its own writes, a new `reschedule()` method on
+`UpdateControl` lets you explicitly request an immediate re-queue.
+
+> **Note**: `InformerEventSource.list(..)` bypasses the additional caches and will not reflect
+> in-flight updates. Use `context.getSecondaryResources(..)` or `InformerEventSource.get(ResourceID)`
+> instead.
+
+See the [reconciler docs](/docs/documentation/reconciler#read-cache-after-write-consistency-and-event-filtering)
+and the [deep-dive blog post](/blog/news/read-after-write-consistency) for full details.
+
+### MicrometerMetricsV2
+
+A new micrometer-based `Metrics` implementation designed with low cardinality in mind. All meters
+are scoped to the controller, not to individual resources, avoiding unbounded cardinality growth as
+resources come and go.
+
+```java
+MeterRegistry registry; // initialize your registry
+Metrics metrics = MicrometerMetricsV2.newMicrometerMetricsV2Builder(registry).build();
+Operator operator = new Operator(client, o -> o.withMetrics(metrics));
+```
+
+Optionally attach a `namespace` tag to per-reconciliation counters (disabled by default):
+
+```java
+Metrics metrics = MicrometerMetricsV2.newMicrometerMetricsV2Builder(registry)
+        .withNamespaceAsTag()
+        .build();
+```
+
+The full list of meters:
+
+| Meter | Type | Description |
+|---|---|---|
+| `reconciliations.active` | gauge | Reconciler executions currently running |
+| `reconciliations.queue` | gauge | Resources queued for reconciliation |
+| `custom_resources` | gauge | Resources tracked by the controller |
+| `reconciliations.execution.duration` | timer | Execution duration with explicit histogram buckets |
+| `reconciliations.started.total` | counter | Reconciliations started |
+| `reconciliations.success.total` | counter | Successful reconciliations |
+| `reconciliations.failure.total` | counter | Failed reconciliations |
+| `reconciliations.retries.total` | counter | Retry attempts |
+| `events.received` | counter | Kubernetes events received |
+
+The execution timer uses explicit bucket boundaries (10ms–30s) to ensure compatibility with
+`histogram_quantile()` in both `PrometheusMeterRegistry` and `OtlpMeterRegistry`.
+
+A ready-to-use **Grafana dashboard** is included at
+[`observability/josdk-operator-metrics-dashboard.json`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/observability/josdk-operator-metrics-dashboard.json).
+
+The
+[`metrics-processing` sample operator](https://github.com/java-operator-sdk/java-operator-sdk/tree/main/sample-operators/metrics-processing)
+provides a complete end-to-end setup with Prometheus, Grafana, and an OpenTelemetry Collector,
+installable via `observability/install-observability.sh`. This is a good starting point for
+verifying metrics in a real cluster.
+
+> **Deprecated**: The original `MicrometerMetrics` (V1) is deprecated as of 5.3.0. It attaches
+> resource-specific metadata as tags to every meter, causing unbounded cardinality. Migrate to
+> `MicrometerMetricsV2`.
+
+See the [observability docs](/docs/documentation/observability#micrometermetricsv2) for the full
+reference.
+
+### Configuration Adapters
+
+A new `ConfigLoader` bridges any key-value configuration source to the JOSDK operator and
+controller configuration APIs. This lets you drive operator behaviour from environment variables,
+system properties, YAML files, or any config library without writing glue code by hand.
+
+The default instance stacks environment variables over system properties out of the box:
+
+```java
+Operator operator = new Operator(ConfigLoader.getDefault().applyConfigs());
+```
+
+Built-in providers: `EnvVarConfigProvider`, `PropertiesConfigProvider`, `YamlConfigProvider`,
+and `AgregatePriorityListConfigProvider` for explicit priority ordering.
+
+`ConfigProvider` is a single-method interface, so adapting any config library (MicroProfile Config,
+SmallRye Config, etc.) takes only a few lines:
+
+```java
+public class SmallRyeConfigProvider implements ConfigProvider {
+    private final SmallRyeConfig config;
+
+    @Override
+    public <T> Optional<T> getValue(String key, Class<T> type) {
+        return config.getOptionalValue(key, type);
+    }
+}
+```
+
+Pass the results when constructing the operator and registering reconcilers:
+
+```java
+var configLoader = new ConfigLoader(new SmallRyeConfigProvider(smallRyeConfig));
+
+Operator operator = new Operator(configLoader.applyConfigs());
+operator.register(new MyReconciler(), configLoader.applyControllerConfigs(MyReconciler.NAME));
+```
+
+See the [configuration docs](/docs/documentation/configuration#loading-configuration-from-external-sources)
+for the full list of supported keys.
+
+### MDC Improvements
+
+**MDC in workflow execution**: MDC context is now propagated through workflow (dependent resource
+graph) execution threads, not just the top-level reconciler thread. Logging from dependent
+resources now carries the same contextual fields as the primary reconciliation.
+
+**`NO_NAMESPACE` for cluster-scoped resources**: Instead of omitting the `resource.namespace` MDC
+key for cluster-scoped resources, the framework now emits `MDCUtils.NO_NAMESPACE`. This makes log
+queries for cluster-scoped resources reliable.
+
+### De-duplicated Secondary Resources from Context
+
+When multiple event sources manage the same resource type, `context.getSecondaryResources(..)` now
+returns a de-duplicated stream. When the same resource appears from more than one source, only the
+copy with the highest resource version is returned.
+
+### Record Desired State in Context
+
+Dependent resources now record their desired state in the `Context` during reconciliation. This
+allows reconcilers and downstream dependents in a workflow to inspect what a dependent resource
+computed as its desired state, which is useful for debugging and composite workflows.
+
+## Additional Improvements
+
+- **Annotation removal using locking**: Finalizer and annotation management no longer uses
+  `createOrReplace`; a locking-based `createOrUpdate` avoids conflicts under concurrent updates.
+- **`KubernetesDependentResource` uses `ResourceOperations` directly**, removing an indirection
+  layer and automatically benefiting from the read-after-write guarantees.
+- **Skip namespace deletion in JUnit extension**: The JUnit extension now supports a flag to skip
+  namespace deletion after a test run, useful for debugging CI failures.
+- **`ManagedInformerEventSource.getCachedValue()` deprecated**: Use
+  `context.getSecondaryResource(..)` instead.
+- **Improved event filtering for multiple parallel updates**: The filtering algorithm now handles
+  cases where multiple parallel updates are in flight for the same resource.
+- `exitOnStopLeading` is being prepared for removal from the public API.
+
+## Migration Notes
+
+### JUnit module rename
+
+```xml
+<!-- before -->
+<artifactId>operator-framework-junit-5</artifactId>
+<!-- after -->
+<artifactId>operator-framework-junit</artifactId>
+```
+
+### `Metrics` interface renames
+
+| v5.2 | v5.3 |
+|---|---|
+| `reconcileCustomResource` | `reconciliationSubmitted` |
+| `reconciliationExecutionStarted` | `reconciliationStarted` |
+| `reconciliationExecutionFinished` | `reconciliationSucceeded` |
+| `failedReconciliation` | `reconciliationFailed` |
+| `finishedReconciliation` | `reconciliationFinished` |
+| `cleanupDoneFor` | `cleanupDone` |
+| `receivedEvent` | `eventReceived` |
+
+`reconciliationFinished(..)` is extended with `RetryInfo`. `monitorSizeOf(..)` is removed.
+
+See the full [migration guide](/docs/migration/v5-3-migration) for details.
+
+## Getting Started
+
+```xml
+<dependency>
+    <groupId>io.javaoperatorsdk</groupId>
+    <artifactId>operator-framework</artifactId>
+    <version>5.3.0</version>
+</dependency>
+```
+
+## All Changes
+
+See the [comparison view](https://github.com/operator-framework/java-operator-sdk/compare/v5.2.0...v5.3.0)
+for the full list of changes.
+
+## Feedback
+
+Please report issues or suggest improvements on our
+[GitHub repository](https://github.com/operator-framework/java-operator-sdk/issues).
+
+Happy operator building! 🚀