Exception while retrieving instance list from AWS API – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.8

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Briefly, this error occurs when OpenSearch is unable to retrieve the instance list from the AWS API. This could be due to network connectivity issues, incorrect AWS credentials, or API throttling. To resolve this, ensure your network connection is stable and reliable. Check your AWS credentials to ensure they are correct and have the necessary permissions. If the issue persists, consider implementing backoff and retry strategies to handle API rate limits.

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This guide will help you check for common problems that cause the log ” Exception while retrieving instance list from AWS API: {} ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: discovery, discovery-ec2, plugins.

Log Context

Log “Exception while retrieving instance list from AWS API: {}” classname is AwsEc2SeedHostsProvider.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :

            // NOTE: we don't filter by security group during the describe instances request for two reasons:
            // 1. differences in VPCs require different parameters during query (ID vs Name)
            // 2. We want to use two different strategies: (all security groups vs. any security groups)
            descInstances = SocketAccess.doPrivileged(() -> clientReference.get().describeInstances(buildDescribeInstancesRequest()));
        } catch (final AmazonClientException e) {
            logger.info("Exception while retrieving instance list from AWS API: {}"; e.getMessage());
            logger.debug("Full exception:"; e);
            return dynamicHosts;

        logger.trace("finding seed nodes...");


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