Briefly, this error occurs when Elasticsearch fails to create a specified index template due to reasons such as insufficient permissions, incorrect template syntax, or a conflict with an existing template. To resolve this, ensure that the user has the necessary permissions to create templates. Check the template syntax for any errors and correct them. If a template with the same name already exists, consider renaming the new template or deleting the existing one if it’s no longer needed.
This guide will help you check for common problems that cause the log ” unable to create template [” + templateName + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: template, plugin.
If you want to learn more about Elasticsearch templates, check out this guide.
Overview
A template in Elasticsearch falls into one of the two following categories and is indexed inside Elasticsearch using its dedicated endpoint:
- Index templates, which are a way to define a set of rules including index settings, mappings and an index pattern. The template is applied automatically whenever a new index is created with the matching pattern. Templates are also used to dynamically apply custom mapping for the fields which are not predefined inside existing mapping.
- Search templates, which help in defining templates for search queries using mustache scripting language. These templates act as a placeholder for variables defined inside the search queries.
Examples
Create a dynamic index template
PUT /_template/template_1?pretty
{
"index_patterns": [
"logs*",
"api*"
],
"settings": {
"number_of_shards": 2
},
"mappings": {
"dynamic_templates": [
{
"strings": {
"match_mapping_type": "string",
"mapping": {
"type": "keyword"
}
}
}
],
"properties": {
"host_name": {
"type": "keyword"
},
"created_at": {
"type": "date"
}
}
}
}Create a search template
POST /_scripts/search_template_1?pretty
{
"script": {
"lang": "mustache",
"source": {
"query": {
"match": {
"description": "{{query_string}}"
}
}
}
}
}Executing a search query using search template
GET /_search/template?pretty
{
"id": "search_template_1",
"params": {
"query_string": "hello world"
}
}The search request will be executed by default on all the indices available in the cluster and can be limited to particular indices using an index parameter.
Notes
- A dynamic index template is always useful when you do not know the field names in advance and want to control their mapping as per the business use case.
Log Context
Log “unable to create template [” + templateName + “]” classname is Monitoring.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
) {
IndexTemplateMetadata updatedTemplate = IndexTemplateMetadata.Builder.fromXContent(parser; templateName);
logger.info("creating template [{}] with version [{}]"; templateName; MonitoringTemplateUtils.TEMPLATE_VERSION);
createdTemplates.add(updatedTemplate);
} catch (IOException e) {
logger.error("unable to create template [" + templateName + "]"; e);
}
// Loading a template involves IO to some specific locations; looking for files with set names.
// We're catching Exception here as we don't want to let anything that might fail in that process bubble up from the
// upgrade template metadata infrastructure as that would prevent a node from starting
} catch (Exception e) {
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