Problem

When OpenMetadata is configured against AWS OpenSearch Serverless (AOSS), several cluster-level API calls fail with 404 because AOSS is a managed serverless service — it has no concept of cluster nodes, shards, or JVM heap. Three methods in OpenSearchGenericManager call endpoints that AOSS does not implement:

The following ERROR is logged repeatedly at runtime:

ERROR [o.o.s.s.o.OpenSearchGenericManager] - Failed to fetch cluster stats
os.org.opensearch.client.transport.TransportException: Request failed with status code '404'

The error is misleading: the cluster is healthy and authentication is working. The 404 is structural — AOSS will never implement these endpoints — not a transient failure.

Additional Impact: Search Service Reported as Unhealthy

getSearchHealthStatus() calls /_cluster/health and returns HEALTHY_STATUS or UNHEALTHY_STATUS via ServicesStatusJobHandler. This result is surfaced in the OpenMetadata UI under Settings → Health Check, and is also available via:

GET /api/v1/system/status

Because /_cluster/health returns 404 on AOSS, the UI reports the search backend as unhealthy even when AOSS is fully functional and serving requests. This is a false negative that will cause operators to incorrectly believe their search backend has a problem.

Detection

AOSS endpoints always follow the pattern <collection-id>.<region>.aoss.amazonaws.com. This makes detection unambiguous without any new configuration:

private boolean isAwsOpenSearchServerless(String host) {
    return host != null && host.endsWith(".aoss.amazonaws.com");
}

Alternatively, the existing SEARCH_AWS_SERVICE_NAME=aoss environment variable (already set in the Helm chart when using AOSS) can serve as a secondary signal.

Proposed Fix

1. Gate cluster/node stats calls behind an AOSS check

Skip calls to unsupported endpoints when running against Serverless, falling back to configured defaults which the auto-tune path already supports:

if (!isAwsOpenSearchServerless(searchConfiguration.getHost())) {
    fetchClusterStats();
} else {
    LOG.debug("Skipping cluster stats fetch — AWS OpenSearch Serverless does not support /_cluster/stats");
}

2. Use GET / as the AOSS health check

/_cluster/health is not available on AOSS. client.info() (GET /) is supported, correctly reflects both connectivity and auth status, and is the appropriate substitute:

private SearchHealthStatus getAossHealthStatus() {
    try {
        client.info(); // GET / — supported by AOSS
        return new SearchHealthStatus(HEALTHY_STATUS);
    } catch (Exception e) {
        return new SearchHealthStatus(UNHEALTHY_STATUS);
    }
}

getSearchHealthStatus() would dispatch to this method when AOSS is detected.

Impact Summary

• Every OpenMetadata deployment using AOSS sees continuous spurious ERROR log entries, making it harder to identify real errors
• The Settings → Health Check panel incorrectly shows the search backend as unhealthy
• Monitoring/alerting systems that treat any ERROR log or the health status API as a signal produce false positives
• The reindexing auto-tune feature is silently non-functional on AOSS deployments

Environment

• OpenMetadata: 1.12.4 / 1.12.5
• Search backend: AWS OpenSearch Serverless (AOSS)
• Deployment: EKS with IRSA authentication (SEARCH_AWS_IAM_AUTH_ENABLED=true, SEARCH_AWS_SERVICE_NAME=aoss)