Operations on Java Operator SDK

Configurations

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The Java Operator SDK (JOSDK) provides abstractions that work great out of the box. However, we recognize that default behavior isn’t always suitable for every use case. Numerous configuration options help you tailor the framework to your specific needs.

Configuration options operate at several levels:

Operator-level using ConfigurationService
Reconciler-level using ControllerConfiguration
DependentResource-level using the DependentResourceConfigurator interface
EventSource-level where some event sources (like InformerEventSource) need fine-tuning to identify which events trigger the associated reconciler

Operator-Level Configuration

Configuration that impacts the entire operator is performed via the ConfigurationService class. ConfigurationService is an abstract class with different implementations based on which framework flavor you use (e.g., Quarkus Operator SDK replaces the default implementation). Configurations initialize with sensible defaults but can be changed during initialization.

Logging

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Contextual Info for Logging with MDC

Logging is enhanced with additional contextual information using MDC. The following attributes are available in most parts of reconciliation logic and during the execution of the controller:

MDC Key	Value added from primary resource
`resource.apiVersion`	`.apiVersion`
`resource.kind`	`.kind`
`resource.name`	`.metadata.name`
`resource.namespace`	`.metadata.namespace`
`resource.resourceVersion`	`.metadata.resourceVersion`
`resource.generation`	`.metadata.generation`
`resource.uid`	`.metadata.uid`

For more information about MDC see this link.

MDC entries during event handling

Although, usually users might not require it in their day-to-day workflow, it is worth mentioning that there are additional MDC entries managed for event handling. Typically, you might be interested in it in your SecondaryToPrimaryMapper related logs. For InformerEventSource and ControllerEventSource the following information is present:

Metrics

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Runtime Info

RuntimeInfo is used mainly to check the actual health of event sources. Based on this information it is easy to implement custom liveness probes.

stopOnInformerErrorDuringStartup setting, where this flag usually needs to be set to false, in order to control the exact liveness properties.

See also an example implementation in the WebPage sample

Metrics

JOSDK provides built-in support for metrics reporting on what is happening with your reconcilers in the form of the Metrics interface which can be implemented to connect to your metrics provider of choice, JOSDK calling the methods as it goes about reconciling resources. By default, a no-operation implementation is provided thus providing a no-cost sane default. A micrometer-based implementation is also provided.

Leader Election

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When running multiple replicas of an operator for high availability, leader election ensures that only one instance actively reconciles resources at a time. JOSDK uses Kubernetes Lease objects for leader election.

Enabling Leader Election

Programmatic Configuration

var operator = new Operator(o -> o.withLeaderElectionConfiguration(
 new LeaderElectionConfiguration("my-operator-lease", "operator-namespace")));

Or using the builder for full control:

import static io.javaoperatorsdk.operator.api.config.LeaderElectionConfigurationBuilder.aLeaderElectionConfiguration;

var config = aLeaderElectionConfiguration("my-operator-lease")
 .withLeaseNamespace("operator-namespace")
 .withIdentity(System.getenv("POD_NAME"))
 .withLeaseDuration(Duration.ofSeconds(15))
 .withRenewDeadline(Duration.ofSeconds(10))
 .withRetryPeriod(Duration.ofSeconds(2))
 .build();

var operator = new Operator(o -> o.withLeaderElectionConfiguration(config));

External Configuration

Leader election can also be configured via properties (e.g. environment variables or a config file).

Generic Helm Chart

Mon, 01 Jan 0001 00:00:00 +0000

A generic, reusable Helm chart for deploying Java operators built with JOSDK is available at helm/generic-helm-chart.

It is intended as a template for operator developers — a starting point that covers common deployment patterns so you don’t have to write a chart from scratch. The chart is maintained on a best-effort basis. Contributions are more than welcome.

The chart is used in the metrics-processing sample operator E2E test to deploy the operator to a cluster via Helm.