Exception while retrieving instance list from AWS API: – How to solve related issues

Opster Team

Jan-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.

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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 Elasticsearch concepts: cloud-aws, discovery, discovery-ec2, hosts and plugins.

Log Context

Log “Exception while retrieving instance list from AWS API: {}” classname is AwsEc2UnicastHostsProvider.java.
We extracted the following from Elasticsearch 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.client().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("building dynamic unicast discovery nodes...");


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