Prior to Elasticsearch 5.0, if we wanted to pre-process documents before indexing them to Elasticsearch, then the only way was to make use of Logstash or pre-process them programmatically/manually and then index them to Elasticsearch. Elasticsearch lacked the ability to pre-process/transform the documents, and it just indexed the document as they were. However, the introduction of a feature called ingest node in Elasticsearch 5.x onwards provided a lightweight solution for pre-processing and enriching documents within Elasticsearch itself before they are indexed.
If an Elasticsearch node is implemented with the default configuration, by default it would be master, data, and ingest enabled (that is, it would act as a master node, data node, and ingest node). To disable ingest on a node, configure the following setting in the elasticsearch.yml
file:
node.ingest: false
The ingest node can be used to pre-process documents before the actual indexing is performed on the document. This...