How To Solve Issues Related to Log – Undefined host-type . Please check your settings.

Prevent Your Next ELK Incident

Try our free Check Up to test if your ES issues are caused from misconfigured settings

Prevent Issue

Updated: Feb-20

In-Page Navigation (click to jump) :

Opster Offer’s World-Class Elasticsearch Expertise In One Powerful Product
Try Our Free ES Check-Up   Prevent Incident

Troubleshooting background

To troubleshoot Elasticsearch log “Undefined host-type . Please check your settings.” it’s important to understand common problems related to Elasticsearch concepts: cloud-azure, discovery, hosts, plugins, repository-azure. See detailed explanations below complete with common problems, examples and useful tips.

[wpseo_breadcrumb]

Discovery in Elasticsearch


What it is

The process known as discovery occurs when an Elasticsearch node starts, restarts or loses contact with the master node for any reason. In those cases, the node needs to contact other nodes in the cluster to find the existing master node for the cluster or initiate the election of a new master node. 

How It Works

Upon startup, each node looks for other nodes, firstly by contacting those ip addresses of eligible master nodes held in previous cluster state.  If they are not available, it will look for nodes based upon the seed host providers mechanisms available.

Seed host providers may be defined in 3 ways: list based, file based or plugin based.  All of these methods will provide a list of IP addresses or hostnames which the node should contact in order to obtain a list of master eligible nodes.  The node will contact all of these addresses in turn, until either an active master is found, or failing that, until sufficient nodes can be found to elect a new master node.

Examples

The simplest form is to define a list of seed host providers in elasticsearch.yml

discovery.seed_hosts:
   - 192.168.1.10:9300
   - 192.168.1.11 
   - seeds.mydomain.com

An alternative way is to refer to a file using the following setting:

discovery.seed_providers: file

The file MUST be placed in the following filepath: $ES_PATH_CONF/unicast_hosts.txt

10.10.10.5
10.10.10.6:9305
10.10.10.5:10005
# an IPv6 address
[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:9301

Note that the use of a port is optional. If not used, then the default port range of 9300-9400 will be used.

If you use AWS or  GCS then you can install and use a PLUGIN to obtain a list of seed hosts from an API.  A plugin also exists for Azure but is deprecated since version 5.

AWS Plugin

A typical configuration could be as follows:

discovery.seed_providers: ec2
discovery.ec2.tag.role: master
discovery.ec2.tag.environment: dev
discovery.ec2.endpoint: ec2.us-east-1.amazonaws.com
cloud.node.auto_attributes: true
cluster.routing.allocation.awareness.attributes: aws_availability_zone

The above configuration would look for all nodes with a tag called “environment” set to “dev” and a tag called “role” set to “master”, in the AWS zone us-east-1. The last two lines set up cluster routing allocation awareness based upon aws availability zones. (Not necessary, but nice to have).

GCE Plugin

A typical configuration could be as follows:

discovery.seed_providers: gce
cloud.gce.project_id: <your-google-project-id>
cloud.gce.zone: <your-zone>
discovery.gce.tags: <my-tag-name>

The above configuration would look for all virtual machines inside your project, zone and with a tag set to the tag name you provide.

Notes and good things to know

Cluster formation depends on correct setup of the network.host settings in elasticsearch.yml.  Make sure that the nodes can reach each other across the network using the IP address / hostname you are using, and are not getting blocked due to firewall settings on the ports required.

Settings in Elasticsearch

What it is 

In ElasticSearch, you can configure cluster-level settings, node-level settings and index level settings. Here we discuss each of them.

A. Cluster Wide Settings

These settings can be either persistent, meaning they apply across restarts, or transient, meaning they won’t survive a full cluster restart. If a transient setting is reset, the first one of these values that is defined is applied:

  • the persistent setting
  • the setting in the configuration file
  • the default value

The order of precedence for cluster settings is:

  1. transient cluster settings
  2. persistent cluster settings
  3. settings in the elasticsearch.yml configuration file
Examples:

An example of persistent cluster settings update:

PUT /_cluster/settings
{
    "persistent" : {
        "indices.recovery.max_bytes_per_sec" : "500mb"
    }
}

An example of a transient update:

PUT /_cluster/settings
{
    "transient" : {
        "indices.recovery.max_bytes_per_sec" : "40mb"
    }
}

B. Index Settings

These are the settings that are applied to individual indices. There is an API to update index level settings.

Examples:

The following API call will set the number of replica shards to 5 for my_index  index.

PUT /my_index/_settings
{
    "index" : {
        "number_of_replicas" : 5    
     }
}

To revert a setting to the default value, use null.

PUT /my_index/_settings
{
    "index" : {
        "refresh_interval" : null
    }
}

C. Node settings

These settings apply to nodes. Nodes can fulfill different roles, for example, there are master nodes , data nodes, or coordinating nodes. Node settings are set through the elasticsearch.yml file for each node. 

Examples:
  • Setting a node to be a data node ( in the elasticsearch.yml file ) 
node.data: true
  • Disabling the ingest role for the node ( which is enabled by default)
node.ingest: false

For production clusters, you will need to run each type of node on a dedicated machine with two or more instances of each, for HA  ( minimum three for master nodes ).

Notes and Good Things to Know:
  • Learning the cluster settings and index settings is important, it can spare you a lot of trouble. For example, if you are going to ingest huge amount of data into an index, then if the number of replica shards are set , for example at 5 replica shards, the indexing process will be super slow because the data will be replicated at the same time it is indexed. What you can do to speed up indexing is to set the replica shards to 0 by updating the settings, and set it back to the original number when indexing is done, using the settings API.

  • Another useful example of using cluster-level settings is when a node has just joined the cluster and the cluster is not assigning any shards to the node. Although shard allocation is enabled by default on all nodes, someone may have disabled shard allocation at some point (for example, in order to perform a rolling restart), and forgot to re-enable it later. To enable shard allocation, you can update the Cluster Settings API:

PUT /_cluster/settings{ "transient":    {       "cluster.routing.allocation.enable" : "all"     }}
  • It’s better to set cluster-wide settings with Settings API instead of with the elasticsearch.yml file and to use the file only for local changes. This will keep the same setting on all nodes. But if you define different settings on different nodes by accident using the elasticsearch.yml configuration file, it is hard to notice these discrepancies.

  • See also: Recoveries


To help troubleshoot related issues we have gathered selected Q&A from the community and issues from Github , please review the following for further information :

1 Elasticsearch : Root mapping definition has unsupported parameters index : not_analyzed 58.89 K 46

 


Log Context

Log ”undefined host_type [{}]. Please check your settings.” classname is AzureUnicastHostsProvider.java
We have extracted the following from Elasticsearch source code to get an in-depth context :

                             logger.trace("no public ip provided. ignoring [{}]..."; instance.getInstanceName());
                        }
                        break;
                    default:
                        // This could never happen!
                        logger.warn("undefined host_type [{}]. Please check your settings."; hostType);
                        return cachedDiscoNodes;
                }

                if (networkAddress == null) {
                    // We have a bad parameter here or not enough information from azure






About Opster

Opster identifies and predicts root causes of Elasticsearch problems, provides recommendations and can automatically perform various actions to prevent issues, optimize performance and save resources.

Learn more: Glossary | Blog| Troubleshooting guides | Error Repository

Need help with any Elasticsearch issue ? Contact Opster