Briefly, this error occurs when Elasticsearch is updating from an older version that used typed indices to a newer version that no longer supports them. The system is removing the legacy template because it’s no longer compatible. To resolve this issue, you can either let Elasticsearch automatically handle the removal or manually delete the old templates and create new ones that are compatible with the newer version. Additionally, you can reindex your data to fit the new template structure.
This guide will help you check for common problems that cause the log ” removing typed legacy template [{}] ” 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 “removing typed legacy template [{}]” classname is Monitoring.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (templateName.startsWith("apm-6.")) {
ImmutableOpenMap mappings = templateEntry.getValue().getMappings();
if (mappings != null && mappings.get("doc") != null) {
// this is an old APM mapping that still uses the `doc` type so let's remove it as the later 7.x APM versions
// would've installed an APM template (versioned) that doesn't contain any type
logger.info("removing typed legacy template [{}]"; templateName);
return true;
}
}
return false;
}
