Configuring Elasticsearch

Elasticsearch ships with good defaults and requires very little configuration. Most settings can be changed on a running cluster using the Cluster update settings API.

The configuration files should contain settings which are node-specific (such as node.name and paths), or settings which a node requires in order to be able to join a cluster, such as cluster.name and network.host.

Config files location

Elasticsearch has three configuration files:

  • elasticsearch.yml for configuring Elasticsearch
  • jvm.options for configuring Elasticsearch JVM settings
  • log4j2.properties for configuring Elasticsearch logging

These files are located in the config directory, whose default location depends on whether or not the installation is from an archive distribution (tar.gz or zip) or a package distribution (Debian or RPM packages).

For the archive distributions, the config directory location defaults to $ES_HOME/config. The location of the config directory can be changed via the ES_PATH_CONF environment variable as follows:

ES_PATH_CONF=/path/to/my/config ./bin/elasticsearch

Alternatively, you can export the ES_PATH_CONF environment variable via the command line or via your shell profile.

For the package distributions, the config directory location defaults to /etc/elasticsearch. The location of the config directory can also be changed via the ES_PATH_CONF environment variable, but note that setting this in your shell is not sufficient. Instead, this variable is sourced from /etc/default/elasticsearch (for the Debian package) and /etc/sysconfig/elasticsearch (for the RPM package). You will need to edit the ES_PATH_CONF=/etc/elasticsearch entry in one of these files accordingly to change the config directory location.

Config file format

The configuration format is YAML. Here is an example of changing the path of the data and logs directories:

path:
    data: /var/lib/elasticsearch
    logs: /var/log/elasticsearch

Settings can also be flattened as follows:

path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch

Environment variable substitution

Environment variables referenced with the ${...} notation within the configuration file will be replaced with the value of the environment variable. For example:

node.name:    ${HOSTNAME}
network.host: ${ES_NETWORK_HOST}

Values for environment variables must be simple strings. Use a comma-separated string to provide values that Elasticsearch will parse as a list. For example, Elasticsearch will split the following string into a list of values for the ${HOSTNAME} environment variable:

export HOSTNAME=“host1,host2"

Cluster and node setting types

Cluster and node settings can be categorized based on how they are configured:

Dynamic

You can configure and update dynamic settings on a running cluster using the cluster update settings API.

You can also configure dynamic settings locally on an unstarted or shut down node using elasticsearch.yml.

It’s best to set dynamic, cluster-wide settings with the cluster update settings API and use elasticsearch.yml only for local configurations. Using the cluster update settings API ensures the setting is the same on all nodes. If you accidentally configure different settings in elasticsearch.yml on different nodes, it can be difficult to notice discrepancies.

Static

Static settings can only be configured on an unstarted or shut down node using elasticsearch.yml.

Static settings must be set on every relevant node in the cluster.