[ANNOUNCE] Apache Solr Operator v0.4.0 released

[Houston Putman <ho...@apache.org>]

The Apache Solr PMC is pleased to announce the release of the Apache Solr Operator v0.4.0.

The Apache Solr Operator is a safe and easy way of managing a Solr ecosystem in Kubernetes.

This release contains numerous bug fixes, optimizations, and improvements, some of which are highlighted below. The release is available for immediate download at:

  <https://solr.apache.org/operator/artifacts.html>

### Solr Operator v0.4.0 Release Highlights:

* A new Helm chart for templating the Solr resource.
  * Users must still run the Solr Operator, preferably through the Solr Operator Helm chart.
* Support for hostpath for the Solr data volume when in ephemeral mode
* Scheduled restarts of Solr Clouds and Solr Prometheus Exporters
* The default version of Solr has been upgraded to 8.9
* Allow for custom service accounts to be used when running Solr
* Upgrade the Zookeeper Operator dependency to v0.2.12
* Allow for ephemeral storage when running a provided Zookeeper cluster
  * The storage type for Zookeeper will default to the option chosen for Solr
* Enable configuration of provided Zookeeper Config options
* Use a more secure base image for the Solr Operator
* The PrometheusExporter now accepts custom pod probes (liveness, readiness, startup)
* Fix permissions in the default bootstrapped security.json
* Allow for terminating the Solr TLS at the ingress
* Allow for loading in TLS information from a mounted directory (SolrCloud and SolrPrometheusExporter)
* SolrCloud now supports separate server and client certs for mTLS
* The Solr Operator supports hot-reloading of TLS client certs used to connect to Solr (enabled by default)

A summary of important changes is published in the documentation at:

  <https://apache.github.io/solr-operator/docs/upgrade-notes.html>

For the most exhaustive list, see the change log on ArtifactHub or view the git history in the solr-operator repo.

  <https://artifacthub.io/packages/helm/apache-solr/solr-operator?modal=changelog>

  <https://github.com/apache/solr-operator/releases/tag/v0.4.0>


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