An index template is a way to tell Elasticsearch how to configure an index when it is created.
For data streams, the index template configures the stream’s backing indices as they are created.
Templates are configured prior to index creation. When an index is created – either manually or through indexing a document – the template settings are used as a basis for creating the index.
There are two types of templates:
- index templates and
- component templates.
Component templates are reusable building blocks that configure mappings, settings, and aliases. While you can use component templates to construct index templates, they aren’t directly applied to a set of indices.
Index templates can contain a collection of component templates, as well as directly specify settings, mappings, and aliases.