187 lines
6.5 KiB
Plaintext
187 lines
6.5 KiB
Plaintext
[[client]]
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== Client
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You can use the *Java client* in multiple ways:
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* Perform standard <<index_,index>>, <<get,get>>,
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<<delete,delete>> and <<search,search>> operations on an
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existing cluster
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* Perform administrative tasks on a running cluster
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* Start full nodes when you want to run Elasticsearch embedded in your
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own application or when you want to launch unit or integration tests
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Obtaining an elasticsearch `Client` is simple. The most common way to
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get a client is by:
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1. Creating an embedded <<node-client,`Node`>> that acts as a node
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within a cluster.
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2. Requesting a `Client` from your embedded `Node`.
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Another manner is by creating a <<transport-client,`TransportClient`>>
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that connects to a cluster.
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*Important:*
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______________________________________________________________________________________________________________________________________________________________
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Please note that you are encouraged to use the same version on client
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and cluster sides. You may hit some incompatibility issues when mixing
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major versions.
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______________________________________________________________________________________________________________________________________________________________
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[[node-client]]
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=== Node Client
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Instantiating a node based client is the simplest way to get a `Client`
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that can execute operations against elasticsearch.
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[source,java]
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--------------------------------------------------
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import static org.elasticsearch.node.NodeBuilder.*;
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// on startup
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Node node = nodeBuilder().node();
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Client client = node.client();
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// on shutdown
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node.close();
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--------------------------------------------------
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When you start a `Node`, it joins an elasticsearch cluster. You can have
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different clusters by simply setting the `cluster.name` setting, or
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explicitly using the `clusterName` method on the builder.
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You can define `cluster.name` in the `/src/main/resources/elasticsearch.yml`
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file in your project. As long as `elasticsearch.yml` is present in the
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classpath, it will be used when you start your node.
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[source,yaml]
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--------------------------------------------------
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cluster.name: yourclustername
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--------------------------------------------------
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Or in Java:
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[source,java]
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--------------------------------------------------
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Node node = nodeBuilder().clusterName("yourclustername").node();
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Client client = node.client();
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--------------------------------------------------
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The benefit of using the `Client` is the fact that operations are
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automatically routed to the node(s) the operations need to be executed
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on, without performing a "double hop". For example, the index operation
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will automatically be executed on the shard that it will end up existing
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at.
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When you start a `Node`, the most important decision is whether it
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should hold data or not. In other words, should indices and shards be
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allocated to it. Many times we would like to have the clients just be
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clients, without shards being allocated to them. This is simple to
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configure by setting either `node.data` setting to `false` or
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`node.client` to `true` (the `NodeBuilder` respective helper methods on
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it):
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[source,java]
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--------------------------------------------------
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import static org.elasticsearch.node.NodeBuilder.*;
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// on startup
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Node node = nodeBuilder().client(true).node();
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Client client = node.client();
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// on shutdown
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node.close();
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--------------------------------------------------
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Another common usage is to start the `Node` and use the `Client` in
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unit/integration tests. In such a case, we would like to start a "local"
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`Node` (with a "local" discovery and transport). Again, this is just a
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matter of a simple setting when starting the `Node`. Note, "local" here
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means local on the JVM (well, actually class loader) level, meaning that
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two *local* servers started within the same JVM will discover themselves
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and form a cluster.
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[source,java]
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--------------------------------------------------
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import static org.elasticsearch.node.NodeBuilder.*;
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// on startup
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Node node = nodeBuilder().local(true).node();
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Client client = node.client();
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// on shutdown
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node.close();
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--------------------------------------------------
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[[transport-client]]
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=== Transport Client
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The `TransportClient` connects remotely to an elasticsearch cluster
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using the transport module. It does not join the cluster, but simply
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gets one or more initial transport addresses and communicates with them
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in round robin fashion on each action (though most actions will probably
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be "two hop" operations).
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[source,java]
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--------------------------------------------------
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// on startup
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Client client = TransportClient.builder().build()
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.addTransportAddress(new InetSocketTransportAddress("host1", 9300))
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.addTransportAddress(new InetSocketTransportAddress("host2", 9300));
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// on shutdown
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client.close();
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--------------------------------------------------
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Note that you have to set the cluster name if you use one different than
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"elasticsearch":
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[source,java]
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--------------------------------------------------
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Settings settings = ImmutableSettings.settingsBuilder()
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.put("cluster.name", "myClusterName").build();
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Client client = TransportClient.builder().settings(settings).build();
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//Add transport addresses and do something with the client...
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--------------------------------------------------
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Or using `elasticsearch.yml` file as shown in <<node-client>>
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The client allows sniffing the rest of the cluster, which adds data nodes
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into its list of machines to use. In this case, note that the IP addresses
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used will be the ones that the other nodes were started with (the
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"publish" address). In order to enable it, set the
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`client.transport.sniff` to `true`:
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[source,java]
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--------------------------------------------------
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Settings settings = ImmutableSettings.settingsBuilder()
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.put("client.transport.sniff", true).build();
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TransportClient client = TransportClient.builder().settings(settings).build();
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--------------------------------------------------
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Other transport client level settings include:
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[cols="<,<",options="header",]
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|=======================================================================
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|Parameter |Description
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|`client.transport.ignore_cluster_name` |Set to `true` to ignore cluster
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name validation of connected nodes. (since 0.19.4)
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|`client.transport.ping_timeout` |The time to wait for a ping response
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from a node. Defaults to `5s`.
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|`client.transport.nodes_sampler_interval` |How often to sample / ping
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the nodes listed and connected. Defaults to `5s`.
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|=======================================================================
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