Briefly, this error occurs when Elasticsearch attempts to add an index template that doesn’t exist. This could be due to a typo in the template name, or the template was not created properly. To resolve this issue, you can check the template name for any spelling errors. If the name is correct, ensure that the template was created successfully. You can do this by using the GET template API to retrieve the template. If it doesn’t exist, you’ll need to create it using the PUT template API.
This guide will help you check for common problems that cause the log ” adding index template [{}] for [{}]; because it doesn’t exist ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, template, plugin.
Overview
In Elasticsearch, an index (plural: indices) contains a schema and can have one or more shards and replicas. An Elasticsearch index is divided into shards and each shard is an instance of a Lucene index.
Indices are used to store the documents in dedicated data structures corresponding to the data type of fields. For example, text fields are stored inside an inverted index whereas numeric and geo fields are stored inside BKD trees.
Examples
Create index
The following example is based on Elasticsearch version 5.x onwards. An index with two shards, each having one replica will be created with the name test_index1
PUT /test_index1?pretty
{
"settings" : {
"number_of_shards" : 2,
"number_of_replicas" : 1
},
"mappings" : {
"properties" : {
"tags" : { "type" : "keyword" },
"updated_at" : { "type" : "date" }
}
}
}List indices
All the index names and their basic information can be retrieved using the following command:
GET _cat/indices?v
Index a document
Let’s add a document in the index with the command below:
PUT test_index1/_doc/1
{
"tags": [
"opster",
"elasticsearch"
],
"date": "01-01-2020"
}Query an index
GET test_index1/_search
{
"query": {
"match_all": {}
}
}Query multiple indices
It is possible to search multiple indices with a single request. If it is a raw HTTP request, index names should be sent in comma-separated format, as shown in the example below, and in the case of a query via a programming language client such as python or Java, index names are to be sent in a list format.
GET test_index1,test_index2/_search
Delete indices
DELETE test_index1
Common problems
- It is good practice to define the settings and mapping of an Index wherever possible because if this is not done, Elasticsearch tries to automatically guess the data type of fields at the time of indexing. This automatic process may have disadvantages, such as mapping conflicts, duplicate data and incorrect data types being set in the index. If the fields are not known in advance, it’s better to use dynamic index templates.
- Elasticsearch supports wildcard patterns in Index names, which sometimes aids with querying multiple indices, but can also be very destructive too. For example, It is possible to delete all the indices in a single command using the following commands:
DELETE /*
To disable this, you can add the following lines in the elasticsearch.yml:
action.destructive_requires_name: true
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 “adding index template [{}] for [{}]; because it doesn’t exist” classname is IndexTemplateRegistry.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
final String templateName = newTemplate.getTemplateName();
final AtomicBoolean creationCheck = templateCreationsInProgress.computeIfAbsent(templateName; key -> new AtomicBoolean(false));
if (creationCheck.compareAndSet(false; true)) {
IndexTemplateMetadata currentTemplate = state.metadata().getTemplates().get(templateName);
if (Objects.isNull(currentTemplate)) {
logger.info("adding index template [{}] for [{}]; because it doesn't exist"; templateName; getOrigin());
putTemplate(newTemplate; creationCheck);
} else if (Objects.isNull(currentTemplate.getVersion()) || newTemplate.getVersion() > currentTemplate.getVersion()) {
// IndexTemplateConfig now enforces templates contain a `version` property; so if the template doesn't have one we can
// safely assume it's an old version of the template.
logger.info("upgrading index template [{}] for [{}] from version [{}] to version [{}]";
