Instantiating a node based client is the simplest way to get a
that can execute operations against elasticsearch.
import static org.elasticsearch.node.NodeBuilder.*; // on startup Node node = nodeBuilder().node(); Client client = node.client(); // on shutdown node.close();
When you start a
Node, it joins an elasticsearch cluster. You can have
different clusters by simply setting the
cluster.name setting, or
explicitly using the
clusterName method on the builder.
You can define
cluster.name in the
file in your project. As long as
elasticsearch.yml is present in the
classpath, it will be used when you start your node.
Or in Java:
Node node = nodeBuilder().clusterName("yourclustername").node(); Client client = node.client();
The benefit of using the
Client is the fact that operations are
automatically routed to the node(s) the operations need to be executed
on, without performing a "double hop". For example, the index operation
will automatically be executed on the shard that it will end up existing
When you start a
Node, the most important decision is whether it
should hold data or not. In other words, should indices and shards be
allocated to it. Many times we would like to have the clients just be
clients, without shards being allocated to them. This is simple to
configure by setting either
node.data setting to
NodeBuilder respective helper methods on
import static org.elasticsearch.node.NodeBuilder.*; // on startup // Embedded node clients behave just like standalone nodes, // which means that they will leave the HTTP port open! Node node = nodeBuilder() .settings(Settings.settingsBuilder().put("http.enabled", false)) .client(true) .node(); Client client = node.client(); // on shutdown node.close();
Another common usage is to start the
Node and use the
unit/integration tests. In such a case, we would like to start a "local"
Node (with a "local" discovery and transport). Again, this is just a
matter of a simple setting when starting the
Node. Note, "local" here
means local on the JVM (well, actually class loader) level, meaning that
two local servers started within the same JVM will discover themselves
and form a cluster.
import static org.elasticsearch.node.NodeBuilder.*; // on startup Node node = nodeBuilder().local(true).node(); Client client = node.client(); // on shutdown node.close();
Embedding a node client into your application is the easiest way to connect to an Elasticsearch cluster, but it carries some downsides.
- Frequently starting and stopping one or more node clients creates unnecessary noise across the cluster.
Embedded node client will respond to outside requests, just like any other client.
- You almost always want to disable HTTP for an embedded node client.