Briefly, this error occurs when Elasticsearch cannot retrieve the default zone information from the metadata server for Google Compute Engine (GCE) discovery service. This could be due to network issues, incorrect configuration, or lack of necessary permissions. To resolve this, ensure that your Elasticsearch instance has the correct permissions to access the metadata server. Also, verify your GCE discovery service configuration in Elasticsearch, making sure it’s correctly set up. Lastly, check your network connectivity to ensure the metadata server is reachable.
This guide will help you check for common problems that cause the log ” unable to resolve default zone from metadata server for GCE discovery service ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: metadata, plugins, discovery-gce, discovery.
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 “unable to resolve default zone from metadata server for GCE discovery service” classname is GceInstancesServiceImpl.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
final String defaultZone = getAppEngineValueFromMetadataServer(
"/computeMetadata/v1/project/attributes/google-compute-default-zone"
);
return Collections.singletonList(defaultZone);
} catch (Exception e) {
logger.warn("unable to resolve default zone from metadata server for GCE discovery service"; e);
}
return null;
}
String getAppEngineValueFromMetadataServer(String serviceURL) throws GeneralSecurityException; IOException {
