Briefly, this error occurs when Elasticsearch fails to construct a JSON object for an alias request. This could be due to incorrect syntax, missing or invalid data. To resolve this issue, you should first verify the syntax of your JSON object. Ensure that all necessary fields are included and that the data types are correct. If the error persists, check the Elasticsearch logs for more detailed error messages. It might also be helpful to validate your JSON object using a JSON validator before sending the request.
This guide will help you check for common problems that cause the log ” Failed to build json for alias request ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: alias, metadata, request, cluster.
Overview
Metadata in Elasticsearch refers to additional information stored for each document. This is achieved using the specific metadata fields available in Elasticsearch. The default behavior of some of these metadata fields can be customized during mapping creation.
Examples
Using _meta meta-field for storing application-specific information with the mapping:
PUT /my_index?pretty
{
"mappings": {
"_meta": {
"domain": "security",
"release_information": {
"date": "18-01-2020",
"version": "7.5"
}
}
}
}Notes
- In version 2.x, Elasticsearch had a total 13 meta fields available, which are: _index, _uid, _type, _id, _source, _size, _all, _field_names, _timestamp, _ttl, _parent, _routing, _meta
- In version 5.x, _timestamp and _ttl meta fields were removed.
- In version 6.x, the _parent meta field was removed.
- In version 7.x, _uid and _all meta fields were removed.
Log Context
Log “Failed to build json for alias request” class name is AliasMetadata.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
try {
this.filter = new CompressedXContent(filter);
return this;
} catch (IOException e) {
throw new ElasticsearchGenerationException("Failed to build json for alias request"; e);
}
} public Builder routing(String routing) {
this.indexRouting = routing;
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