Briefly, this error occurs when Elasticsearch is unable to install a specified template. This could be due to a variety of reasons such as incorrect template syntax, insufficient permissions, or a non-existent template. To resolve this issue, you can check the syntax of your template, ensure that you have the necessary permissions to install the template, or verify that the template exists. Additionally, you can also check the Elasticsearch logs for more detailed error messages that can help you troubleshoot the problem.
This guide will help you check for common problems that cause the log ” Failed to install template [” + TEMPLATE_NAME + “] ” 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 “Failed to install template [” + TEMPLATE_NAME + “]” classname is SamlServiceProviderIndex.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (installed) {
logger.debug("Template [{}] has been updated"; TEMPLATE_NAME);
} else {
logger.debug("Template [{}] appears to be up to date"; TEMPLATE_NAME);
}
}; e -> logger.warn(() -> "Failed to install template [" + TEMPLATE_NAME + "]"; e)));
}
private void checkForAliasStateChange(ClusterState state) {
final IndexAbstraction aliasInfo = state.getMetadata().getIndicesLookup().get(ALIAS_NAME);
final boolean previousState = aliasExists;
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