I've been working with Elasticsearch\Kibana for quite some time now but recently considered moving to Graylog. If I understand this correctly, I should be able to query all my current indices through Graylog just as with Kibana. The thing is I dont see anything under System -> Indices:
Do I need to re-create index sets much like Kibana's Index Patterns or is there anything else that I'm missing?
Graylog expects full authority over its indices.
It's not possible to query arbitrary existing Elasticsearch indices with Graylog as it's expecting the documents to have a specific format.
You can query existing Elasticsearch indices created and populated by Graylog with Kibana, though.
For an explanation of the Graylog index model, please refer to http://docs.graylog.org/en/2.3/pages/configuration/index_model.html