Fix #1167 - Remove Elasticsearch module and update README to notify u…

…sers (#1182)

external/elasticsearch/README.md

@@ -1,70 +1,6 @@
 storm-crawler-elasticsearch
 ===========================
 
-A collection of resources for [Elasticsearch](https://www.elastic.co/products/elasticsearch):
-* [IndexerBolt](https://github.org/apache/incubator-stormcrawler/blob/master/external/elasticsearch/src/main/java/org/apache/stormcrawler/elasticsearch/bolt/IndexerBolt.java) for indexing documents crawled with StormCrawler
-* [Spouts](https://github.org/apache/incubator-stormcrawler/blob/master/external/elasticsearch/src/main/java/org/apache/stormcrawler/elasticsearch/persistence/AggregationSpout.java) and [StatusUpdaterBolt](https://github.org/apache/incubator-stormcrawler/blob/master/external/elasticsearch/src/main/java/org/apache/stormcrawler/elasticsearch/persistence/StatusUpdaterBolt.java) for persisting URL information in recursive crawls
-* [MetricsConsumer](https://github.org/apache/incubator-stormcrawler/blob/master/external/elasticsearch/src/main/java/org/apache/stormcrawler/elasticsearch/metrics/MetricsConsumer.java)
-* [StatusMetricsBolt](https://github.org/apache/incubator-stormcrawler/blob/master/external/elasticsearch/src/main/java/org/apache/stormcrawler/elasticsearch/metrics/StatusMetricsBolt.java) for sending the breakdown of URLs per status as metrics and display its evolution over time.
-
-as well as an archetype containing a basic crawl topology and its configuration.
-
-We also have resources for [Kibana](https://www.elastic.co/products/kibana) to build basic real-time monitoring dashboards for the crawls. A dashboard for [Grafana](http://grafana.com/) is also [available](https://grafana.com/dashboards/2363).
-
-Getting started
----------------------
-
-Use the archetype for Elasticsearch with:
-
-`mvn archetype:generate -DarchetypeGroupId=org.apache.stormcrawler -DarchetypeArtifactId=storm-crawler-elasticsearch-archetype -DarchetypeVersion=2.11`
-
-You'll be asked to enter a groupId (e.g. com.mycompany.crawler), an artefactId (e.g. stormcrawler), a version, a package name and details about the user agent to use.
-
-This will not only create a fully formed project containing a POM with the dependency above but also a set of resources, configuration files and a topology class. Enter the directory you just created (should be the same as the artefactId you specified earlier) and follow the instructions on the README file.
-
-Video tutorial
----------------------
-
-[![Video tutorial](https://i.ytimg.com/vi/8kpJLPdhvLw/hqdefault.jpg)](https://youtu.be/8kpJLPdhvLw)
-
-
-Kibana
----------------------
-
-To import the dashboards into a local instance of Kibana, go into the folder _kibana_ and run the script _importKibana.sh_. 
-
-You should see something like 
-
-```
-Importing status dashboard into Kibana
-{"success":true,"successCount":4}
-Importing metrics dashboard into Kibana
-{"success":true,"successCount":9}
-```
-
-The [dashboard screen](http://localhost:5601/app/kibana#/dashboards) should show both the status and metrics dashboards. If you click on `Crawl Status`, you should see 2 tables containing the count of URLs per status and the top hostnames per URL count.
-The [Metrics dashboard](http://localhost:5601/app/kibana#/dashboard/Crawl-metrics) can be used to monitor the progress of the crawl.
-
-The file _storm.ndjson_ is used to display some of Storm's internal metrics and is not added by default.
-
-#### Per time period metric indices (optional)
-
-The _metrics_ index can be configured per tine period. This best practice is [discussed on the Elastic website](https://www.elastic.co/guide/en/elasticsearch/guide/current/time-based.html).
-
-The crawler config YAML must be updated to use an optional argument as shown below to have one index per day:
-
-```
- #Metrics consumers:
-    topology.metrics.consumer.register:
-         - class: "org.apache.stormcrawler.elasticsearch.metrics.MetricsConsumer"
-           parallelism.hint: 1
-           argument: "yyyy-MM-dd"
-```
-
-
-
-
-
-
-
-
+Elasticsearch has changed its licence to `Elastic License 2.0` in recent releases, which is not an ASFv2 compliant licence.
+Therefore, the corresponding module was removed. Users can migrate to the `opensearch` module and follow the
+[opensearch upgrade guideline](https://opensearch.org/docs/latest/upgrade-to/upgrade-to/) to migrate existing elasticsearch installations.