Index templates let you initialize new indices with predefined mappings and settings. For example, if you continuously index log data, you can define an index template so that all of these indices have the same number of shards and replicas.
This command creates a template named `daily_logs` and applies it to any new index whose name matches the regular expression `logs-2020-01-*` and also adds it to the `my_logs` alias:
To get a list of all templates that match a pattern:
```json
GET _index_template/daily*
```
To check if a specific template exists:
```json
HEAD _index_template/<name>
```
## Configure multiple templates
You can create multiple index templates for your indices. If the index name matches more than one template, OpenSearch merges all mappings and settings from all matching templates and applies them to the index.
The settings from the more recently created index templates override the settings of older index templates. So, you can first define a few common settings in a generic template that can act as a catch-all and then add more specialized settings as required.
An even better approach is to explicitly specify template priority using the `order` parameter. OpenSearch applies templates with lower priority numbers first and then overrides them with templates with higher priority numbers.
For example, say you have the following two templates that both match the `logs-2020-01-02` index and there’s a conflict in the `number_of_shards` field:
#### Template 1
```json
PUT _index_template/template-01
{
"index_patterns": [
"logs*"
],
"priority": 0,
"template": {
"settings": {
"number_of_shards": 2
}
}
}
```
#### Template 2
```json
PUT _index_template/template-02
{
"index_patterns": [
"logs-2020-01-*"
],
"priority": 1,
"template": {
"settings": {
"number_of_shards": 3
}
}
}
```
Because `template-02` has a higher `priority` value, it takes precedence over `template-01` . The `logs-2020-01-02` index would have the `number_of_shards` value as 3.
