Command line flags using single dash notation must be now specified as the first arguments. For example if previously using:

./elasticsearch --node.name=test_node -Des.path.conf=/opt/elasticsearch/conf/test_node

This will now need to be changed to:

./elasticsearch -Des.path.conf=/opt/elasticsearch/conf/test_node --node.name=test_node

for the flag to take effect.

The script.disable_dynamic node setting has been replaced by fine-grained script settings described in the scripting docs. The following setting previously used to enable dynamic or inline scripts:

script.disable_dynamic: false

It should be replaced with the following two settings in elasticsearch.yml that achieve the same result:

script.inline: on
script.indexed: on

Any settings which accept time or byte values must now be specified with units. For instance, it is too easy to set the refresh_interval to 1 millisecond instead of 1 second:

PUT _settings
{
  "index.refresh_interval": 1
}

In 2.0, the above request will throw an exception. Instead the refresh interval should be set to "1s" for one second.

The tiered merge policy is now the only supported merge policy. These settings have been removed:

Merge throttling now uses a feedback loop to auto-throttle. These settings have been removed:

The node.enable_custom_paths setting has been removed and replaced by the path.shared_data setting to allow shadow replicas with custom paths to work with the security manager. For example, if your previous configuration had:

node.enable_custom_paths: true

And you created an index using shadow replicas with index.data_path set to /opt/data/my_index with the following:

PUT /my_index
{
  "index": {
    "number_of_shards": 1,
    "number_of_replicas": 4,
    "data_path": "/opt/data/my_index",
    "shadow_replicas": true
  }
}

For 2.0, you will need to set path.shared_data to a parent directory of the index’s data_path, so:

path.shared_data: /opt/data

The setting names for configuring the resource watcher have been renamed to prevent clashes with the watcher plugin

The parameter indices.analysis.hunspell.dictionary.location has been removed, and <path.conf>/hunspell is always used.

The CORS allowed origins setting, http.cors.allow-origin, no longer has a default value. Previously, the default value was *, which would allow CORS requests from any origin and is considered insecure. The http.cors.allow-origin setting should be specified with only the origins that should be allowed, like so:

http.cors.allow-origin: /https?:\/\/localhost(:[0-9]+)?/

JSONP callback support has now been removed. CORS should be used to access Elasticsearch over AJAX instead:

http.cors.enabled: true
http.cors.allow-origin: /https?:\/\/localhost(:[0-9]+)?/

The memory / ram store (index.store.type) option was removed in Elasticsearch. In-memory indices are no longer supported.

Log messages are now truncated at 10,000 characters. This can be changed in the logging.yml configuration file with the file.layout.conversionPattern setting.

It is no longer possible to specify a custom config file with the CONF_FILE environment variable, or the -Des.config, -Des.default.config, or -Delasticsearch.config parameters.

Instead, the config file must be named elasticsearch.yml and must be located in the default config/ directory, unless a custom config directory is specified.

The location of a custom config directory may be specified as follows:

./bin/elasticsearch --path.conf=/path/to/conf/dir
./bin/plugin -Des.path.conf=/path/to/conf/dir install analysis-icu

When using the RPM or debian packages, the plugin script and the init/service scripts will consult the CONF_DIR environment variable to check for a custom config location. The value of the CONF_DIR variable can be set in the environment config file which is located either in /etc/default/elasticsearch or /etc/sysconfig/elasticsearch.

It is no longer possible to set custom file path outside CONF_DIR for *_path settings in char or token filters. You must specify either relative path to CONF_DIR location or absolute path inside CONF_DIR location.

The ES_CLASSPATH environment variable is no longer used to set the class path. External libraries should preferably be loaded using the plugin mechanism or, if you really must, be copied to the lib/ directory.