Add Production-ready druid cluster spec

docs/README.md

@@ -13,6 +13,7 @@ The operator simplifies the management of Druid clusters with its custom logic t
 * [Example Specs](./examples.md)
 * [Developer Documentation](./dev_doc.md)
 * [Migration To Kubebuilder V3 in the Upcoming Version](./kubebuilder_v3_migration.md)
+
 ---
 
 :warning: You won't find any documentation about druid itself in this repository.
@@ -21,3 +22,20 @@ If you need details about how to architecture your druid cluster you can consult
 * [Druid introduction](<https://druid.apache.org/docs/latest/design/index.html>)
 * [Druid architecture](https://druid.apache.org/docs/latest/design/architecture.html)
 * [Druid configuration reference](https://druid.apache.org/docs/latest/configuration/index.html)
+
+---
+
+[German company iunera has published their druid cluster spec](https://www.iunera.com/) in github which is used in the context of a software project by the German Ministry for Digital and Transport. The spec have the following features:
+
+* Kubernetes-native Druid
+  * K8S jobs instead of Middlemanager with separated [pod-templates](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/druidcluster/podTemplates/default-task-template.yaml)
+  * [Service Discovery by Kubernetes](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/druidcluster/iuneradruid-cluster.yaml#L172) aka. no zookeeper
+  * [HPA for historical nodes](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/druidcluster/hpa.yaml) / extended [Metrics Exporter](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/metrics/druid-exporter.helm.yaml)
+* Multiple [Authenticator/Authorizer](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/druidcluster/iuneradruid-cluster.yaml#L88) (Basic Auth and Azure AD Authentication with pac4j)
+* [Examples](https://github.com/iunera/druid-cluster-config/tree/main/_authentication-and-authorization-druid) for authorization and authentication
+* Based on druid-operator and [flux-cd](https://fluxcd.io/flux/)
+* Secrets managed by [SOPS](https://fluxcd.io/flux/guides/mozilla-sops/) and [ingested as Environment Variables](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/druidcluster/iuneradruid-cluster.yaml#L245)
+* Postgres as Metadata Store (incl. [Helmchart Config](https://github.com/iunera/druid-cluster-config/blob/main/kubernetes/druid/postgres/postgres.helm.yaml))
+* All endpoints TLS encrypted incl. [Howto](https://github.com/iunera/druid-cluster-config/blob/main/README.md#cluster-internal-tls-encryption)
+
+Link to the complete config file: https://github.com/iunera/druid-cluster-config