earthquake-data: update docs and nifi flows

docs/modules/demos/pages/nifi-kafka-druid-earthquake-data.adoc

@@ -27,7 +27,7 @@ Additionally, we have to use the FQDN service names (including the namespace), s
 To run this demo, your system needs at least:
 
 * 9 {k8s-cpu}[cpu units] (core/hyperthread)
-* 42GiB memory
+* 42GiB memory (minimum of 16GiB per node)
 * 75GiB disk storage
 
 == Overview
@@ -86,6 +86,111 @@ $ stackablectl stacklet list
 
 include::partial$instance-hint.adoc[]
 
+== Inspect the data in Kafka
+
+Kafka is an event streaming platform to stream the data in near real-time.
+All the messages put in and read from Kafka are structured in dedicated queues called topics.
+The test data will be put into a topic called `earthquakes`.
+The records are produced (written) by the test data generator and consumed (read) by Druid afterwards in the same order they were created.
+
+Kafka uses mutual TLS, so clients wanting to connect to Kafka must present a valid TLS certificate.
+The easiest way to obtain this is to shell into the `kafka-broker-default-0` Pod, as we will do in the following section for demonstration purposes.
+For a production setup, you should spin up a dedicated Pod provisioned with a certificate acting as a Kafka client instead of shell-ing into the Kafka Pod.
+
+=== List the available Topics
+
+You can execute a command on the Kafka broker to list the available topics as follows:
+
+// In the following commands the kcat-prober container instead of the kafka container is used to send requests to Kafka.
+// This is necessary because kcat cannot use key- and truststore files with empty passwords, which are mounted here to the kafka container.
+// However, the kcat-prober container has TLS certificates mounted, which can be used by kcat to connect to Kafka.
+[source,console]
+----
+$ kubectl exec kafka-broker-default-0 -c kafka -- \
+/stackable/kafka/bin/kafka-topics.sh \
+--describe \
+--bootstrap-server kafka-broker-default-headless.default.svc.cluster.local:9093 \
+--command-config /stackable/config/client.properties
+...
+Topic: earthquakes	TopicId: ND51v_XcQPK4Ilm7A35Pag	PartitionCount: 8	ReplicationFactor: 1	Configs: min.insync.replicas=1,segment.bytes=100000000,retention.bytes=900000000
+	Topic: earthquakes	Partition: 0	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 1	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 2	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 3	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 4	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 5	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 6	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+	Topic: earthquakes	Partition: 7	Leader: 1243966388	Replicas: 1243966388	Isr: 1243966388	Elr: 	LastKnownElr:
+----
+
+You can see that Kafka consists of one broker, and the topic `earthquakes` with eight partitions has been created. To
+see some records sent to Kafka, run the following command. You can change the number of records to print via the `--max-messages`
+parameter.
+
+[source,console]
+----
+$ kubectl exec kafka-broker-default-0 -c kafka -- \
+/stackable/kafka/bin/kafka-console-consumer.sh \
+--bootstrap-server kafka-broker-default-headless.default.svc.cluster.local:9093 \
+--consumer.config /stackable/config/client.properties \
+--topic earthquakes \
+--offset earliest \
+--partition 0 \
+--max-messages 1
+----
+
+Below is an example of the output of one record:
+
+[source,json]
+----
+ {
+   "time":"1950-02-07T10:37:29.240Z",
+   "latitude":45.949,
+   "longitude":151.59,
+   "depth":35.0,
+   "mag":5.94,
+   "magType":"mw",
+   "nst":null,
+   "gap":null,
+   "dmin":null,
+   "rms":null,
+   "net":"iscgem",
+   "id":"iscgem895202",
+   "updated":"2022-04-26T18:23:38.377Z",
+   "place":"Kuril Islands",
+   "type":"earthquake",
+   "horizontalError":null,
+   "depthError":12.6,
+   "magError":0.55,
+   "magNst":null,
+   "status":"reviewed",
+   "locationSource":"iscgem",
+   "magSource":"iscgem"
+}
+----
+
+If you are interested in how many records have been produced to the Kafka topic so far, use the following command.
+
+[source,console]
+----
+$ kubectl exec kafka-broker-default-0 -c kafka -- \
+/stackable/kafka/bin/kafka-get-offsets.sh \
+--bootstrap-server kafka-broker-default-headless.default.svc.cluster.local:9093 \
+--command-config /stackable/config/client.properties \
+--topic earthquakes
+...
+earthquakes:0:757379
+earthquakes:1:759282
+earthquakes:2:761924
+earthquakes:3:761339
+earthquakes:4:759059
+earthquakes:5:767695
+earthquakes:6:771457
+earthquakes:7:768301
+----
+
+If you calculate `765,000` records * `8` partitions, you end up with ~ 6,120,000 records.
+
 == NiFi
 
 NiFi is used to fetch earthquake data from the internet and ingest it into Kafka.

stacks/nifi-kafka-druid-superset-s3/nifi.yaml

@@ -21,7 +21,7 @@ spec:
           min: "500m"
           max: "4"
         memory:
-          limit: '6Gi'
+          limit: "6Gi"
         storage:
           contentRepo:
             capacity: "10Gi"
@@ -33,6 +33,10 @@ spec:
             capacity: "4Gi"
           stateRepo:
             capacity: "1Gi"
+    configOverrides:
+      nifi.properties:
+        nifi.web.https.sni.required: "false"
+        nifi.web.https.sni.host.check: "false"
     roleGroups:
       default:
         replicas: 1