docs: Fix getting started guide to use postgres and TLS

docs/modules/druid/examples/getting_started/druid.yaml.j2

@@ -7,17 +7,18 @@ spec:
   image:
     productVersion: 30.0.0
   clusterConfig:
+    listenerClass: external-stable # This exposes your Stacklet outside of Kubernetes. Remove this configuration if this is not desired
+    zookeeperConfigMapName: simple-druid-znode
     deepStorage:
       hdfs:
         configMapName: simple-hdfs
-        directory: /data
+        directory: /druid
     metadataStorageDatabase:
-      dbType: derby
-      connString: jdbc:derby://localhost:1527/var/druid/metadata.db;create=true
-      host: localhost
-      port: 1527
-    tls: null
-    zookeeperConfigMapName: simple-druid-znode
+      dbType: postgresql
+      connString: jdbc:postgresql://postgresql-druid/druid
+      host: postgresql-druid
+      port: 5432
+      credentialsSecret: druid-db-credentials
   brokers:
     roleGroups:
       default:
@@ -38,3 +39,11 @@ spec:
     roleGroups:
       default:
         replicas: 1
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: druid-db-credentials
+stringData:
+  username: druid
+  password: druid

docs/modules/druid/examples/getting_started/getting_started.sh.j2

@@ -100,6 +100,17 @@ kubectl rollout status --watch statefulset/simple-hdfs-journalnode-default --tim
 kubectl rollout status --watch statefulset/simple-hdfs-namenode-default --timeout=300s
 # end::watch-hdfs-rollout[]
 
+echo "Installing PostgreSQL for Druid"
+# tag::helm-install-postgres[]
+helm install postgresql-druid \
+--repo https://charts.bitnami.com/bitnami postgresql \
+--version 16.1.2 \
+--set auth.database=druid \
+--set auth.username=druid \
+--set auth.password=druid \
+--wait
+# end::helm-install-postgres[]
+
 echo "Install DruidCluster from druid.yaml"
 # tag::install-druid[]
 kubectl apply --server-side -f druid.yaml

docs/modules/druid/examples/getting_started/hdfs.yaml.j2

@@ -10,10 +10,14 @@ spec:
     dfsReplication: 1
     zookeeperConfigMapName: simple-hdfs-znode
   nameNodes:
+    config:
+      listenerClass: external-stable # This exposes your Stacklet outside of Kubernetes. Remove this configuration if this is not desired
     roleGroups:
       default:
         replicas: 2
   dataNodes:
+    config:
+      listenerClass: external-unstable # This exposes your Stacklet outside of Kubernetes. Remove this configuration if this is not desired
     roleGroups:
       default:
         replicas: 1

docs/modules/druid/pages/getting_started/first_steps.adoc

@@ -10,6 +10,7 @@ Three things need to be installed to have a Druid cluster:
 
 * A ZooKeeper instance for internal use by Druid
 * An HDFS instance to be used as a backend for deep storage
+* A PostgreSQL database to store the metadata of Druid
 * The Druid cluster itself
 
 Create them in this order, each one is created by applying a manifest file.
@@ -47,6 +48,17 @@ And apply it:
 include::example$getting_started/getting_started.sh[tag=install-hdfs]
 ----
 
+
+=== PostgreSQL
+
+Install a PostgreSQL database using `helm`.
+If you already have a PostgreSQL instance, you can skip this step and use your own below.
+
+[source,bash]
+----
+include::example$getting_started/getting_started.sh[tag=helm-install-postgres]
+----
+
 === Druid
 
 Create a file named `druid.yaml` with the following contents:
@@ -94,7 +106,9 @@ simple-hdfs-namenode-default         2/2     6m
 simple-zk-server-default             3/3     7m
 ----
 
-Then, create a port-forward for the Druid Router:
+Ideally you use `stackablectl stacklet list` to find out the address the Druid router is reachable at and use that address.
+
+As an alternative, you can create a port-forward for the Druid Router:
 
 ----
 include::example$getting_started/getting_started.sh[tag=port-forwarding]