Briefly, this error occurs when Elasticsearch cannot access the necessary credentials to authenticate with a service, typically Google Cloud. This could be due to misconfiguration, missing files, or incorrect environment variables. To resolve this issue, ensure that the Google Cloud SDK is properly installed and configured. Also, check that the environment variable ‘GOOGLE_APPLICATION_CREDENTIALS’ is set correctly, pointing to the JSON file containing your service account key. If you’re using a compute engine, make sure it has the necessary permissions to access the service.
This guide will help you check for common problems that cause the log ” failed to load Application Default Credentials ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repository-gcs, repositories.
Overview
An Elasticsearch snapshot provides a backup mechanism that takes the current state and data in the cluster and saves it to a repository (read snapshot for more information). The backup process requires a repository to be created first. The repository needs to be registered using the _snapshot endpoint, and multiple repositories can be created per cluster. The following repository types are supported:
Repository types
| Repository type | Configuration type |
|---|---|
| Shared file system | Type: “fs” |
| S3 | Type : “s3” |
| HDFS | Type :“hdfs” |
| Azure | Type: “azure” |
| Google Cloud Storage | Type : “gcs” |
Examples
To register an “fs” repository:
PUT _snapshot/my_repo_01
{
"type": "fs",
"settings": {
"location": "/mnt/my_repo_dir"
}
}Notes and good things to know
- S3, HDFS, Azure and Google Cloud require a relevant plugin to be installed before it can be used for a snapshot.
- The setting, path.repo: /mnt/my_repo_dir needs to be added to elasticsearch.yml on all the nodes if you are planning to use the repo type of file system. Otherwise, it will fail.
- When using remote repositories, the network bandwidth and repository storage throughput should be high enough to complete the snapshot operations normally, otherwise you will end up with partial snapshots.
Log Context
Log “failed to load Application Default Credentials” classname is GoogleCloudStorageService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
if (gcsClientSettings.getCredential() == null) {
try {
storageOptionsBuilder.setCredentials(SocketAccess.doPrivilegedIOException(GoogleCredentials::getApplicationDefault));
} catch (Exception e) {
logger.warn("failed to load Application Default Credentials"; e);
}
} else {
ServiceAccountCredentials serviceAccountCredentials = gcsClientSettings.getCredential();
// override token server URI
final URI tokenServerUri = gcsClientSettings.getTokenUri();
