202 lines
8.3 KiB
Plaintext
202 lines
8.3 KiB
Plaintext
[[modules-transport]]
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=== Transport
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REST clients send requests to your {es} cluster over <<modules-http,HTTP>>, but
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the node that receives a client request cannot always handle it alone and must
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normally pass it on to other nodes for further processing. It does this using
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the transport networking layer. The transport layer is used for all internal
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communication between nodes within a cluster, all communication with the nodes
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of a <<modules-remote-clusters,remote cluster>>, and also by the
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`TransportClient` in the {es} Java API.
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[[transport-settings]]
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==== Transport settings
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The following settings can be configured for the internal transport that
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communicates over TCP. These settings also use the common
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<<modules-network,network settings>>.
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`transport.port`::
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A bind port range. Defaults to `9300-9400`.
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`transport.publish_port`::
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The port that other nodes in the cluster
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should use when communicating with this node. Useful when a cluster node
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is behind a proxy or firewall and the `transport.port` is not directly
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addressable from the outside. Defaults to the actual port assigned via
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`transport.port`.
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`transport.bind_host`::
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The host address to bind the transport service to. Defaults to
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`transport.host` (if set) or `network.bind_host`.
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`transport.publish_host`::
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The host address to publish for nodes in the cluster to connect to.
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Defaults to `transport.host` (if set) or `network.publish_host`.
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`transport.host`::
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Used to set the `transport.bind_host` and the `transport.publish_host`.
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`transport.connect_timeout`::
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The connect timeout for initiating a new connection (in
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time setting format). Defaults to `30s`.
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`transport.compress`::
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Set to `true` to enable compression (`DEFLATE`) between
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all nodes. Defaults to `false`.
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`transport.ping_schedule`::
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Schedule a regular application-level ping message
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to ensure that transport connections between nodes are kept alive. Defaults to
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`5s` in the transport client and `-1` (disabled) elsewhere. It is preferable
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to correctly configure TCP keep-alives instead of using this feature, because
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TCP keep-alives apply to all kinds of long-lived connections and not just to
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transport connections.
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`transport.tcp.no_delay`::
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Enable or disable the https://en.wikipedia.org/wiki/Nagle%27s_algorithm[TCP no delay]
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setting. Defaults to `network.tcp.no_delay`.
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`transport.tcp.keep_alive`::
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Configures the `SO_KEEPALIVE` option for this socket, which
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determines whether it sends TCP keepalive probes.
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Defaults to `network.tcp.keep_alive`.
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`transport.tcp.keep_idle`::
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Configures the `TCP_KEEPIDLE` option for this socket, which
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determines the time in seconds that a connection must be idle before
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starting to send TCP keepalive probes. Defaults to `network.tcp.keep_idle` if set,
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or the system default otherwise.
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This value cannot exceed `300` seconds. In cases where the system default
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is higher than `300`, the value is automatically lowered to `300`. Only applicable on
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Linux and macOS, and requires Java 11 or newer.
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`transport.tcp.keep_interval`::
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Configures the `TCP_KEEPINTVL` option for this socket,
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which determines the time in seconds between sending TCP keepalive probes.
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Defaults to `network.tcp.keep_interval` if set, or the system default otherwise.
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This value cannot exceed `300` seconds. In cases where the system default is higher than `300`,
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the value is automatically lowered to `300`. Only applicable on Linux and macOS,
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and requires Java 11 or newer.
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`transport.tcp.keep_count`::
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Configures the `TCP_KEEPCNT` option for this socket, which
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determines the number of unacknowledged TCP keepalive probes that may be
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sent on a connection before it is dropped. Defaults to `network.tcp.keep_count`
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if set, or the system default otherwise. Only applicable on Linux and macOS, and
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requires Java 11 or newer.
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transport.tcp.reuse_address::
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Should an address be reused or not. Defaults to `network.tcp.reuse_address`.
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`transport.tcp.send_buffer_size`::
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The size of the TCP send buffer (specified with <<size-units,size units>>).
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Defaults to `network.tcp.send_buffer_size`.
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`transport.tcp.receive_buffer_size`::
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The size of the TCP receive buffer (specified with <<size-units,size units>>).
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Defaults to `network.tcp.receive_buffer_size`.
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[[transport-profiles]]
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===== Transport profiles
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Elasticsearch allows you to bind to multiple ports on different interfaces by
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the use of transport profiles. See this example configuration
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[source,yaml]
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--------------
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transport.profiles.default.port: 9300-9400
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transport.profiles.default.bind_host: 10.0.0.1
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transport.profiles.client.port: 9500-9600
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transport.profiles.client.bind_host: 192.168.0.1
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transport.profiles.dmz.port: 9700-9800
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transport.profiles.dmz.bind_host: 172.16.1.2
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--------------
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The `default` profile is special. It is used as a fallback for any other
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profiles, if those do not have a specific configuration setting set, and is how
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this node connects to other nodes in the cluster.
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The following parameters can be configured on each transport profile, as in the
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example above:
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* `port`: The port to which to bind.
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* `bind_host`: The host to which to bind.
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* `publish_host`: The host which is published in informational APIs.
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Profiles also support all the other transport settings specified in the
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<<transport-settings,transport settings>> section, and use these as defaults.
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For example, `transport.profiles.client.tcp.reuse_address` can be explicitly
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configured, and defaults otherwise to `transport.tcp.reuse_address`.
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[[long-lived-connections]]
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===== Long-lived idle connections
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A transport connection between two nodes is made up of a number of long-lived
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TCP connections, some of which may be idle for an extended period of time.
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Nonetheless, Elasticsearch requires these connections to remain open, and it
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can disrupt the operation of your cluster if any inter-node connections are
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closed by an external influence such as a firewall. It is important to
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configure your network to preserve long-lived idle connections between
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Elasticsearch nodes, for instance by leaving `tcp.keep_alive` enabled and
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ensuring that the keepalive interval is shorter than any timeout that might
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cause idle connections to be closed, or by setting `transport.ping_schedule` if
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keepalives cannot be configured. Devices which drop connections when they reach
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a certain age are a common source of problems to Elasticsearch clusters, and
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must not be used.
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[[request-compression]]
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===== Request compression
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By default, the `transport.compress` setting is `false` and network-level
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request compression is disabled between nodes in the cluster. This default
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normally makes sense for local cluster communication as compression has a
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noticeable CPU cost and local clusters tend to be set up with fast network
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connections between nodes.
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The `transport.compress` setting always configures local cluster request
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compression and is the fallback setting for remote cluster request compression.
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If you want to configure remote request compression differently than local
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request compression, you can set it on a per-remote cluster basis using the
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<<remote-cluster-settings,`cluster.remote.${cluster_alias}.transport.compress` setting>>.
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[[response-compression]]
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===== Response compression
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The compression settings do not configure compression for responses. {es} will
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compress a response if the inbound request was compressed--even when compression
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is not enabled. Similarly, {es} will not compress a response if the inbound
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request was uncompressed--even when compression is enabled.
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[[transport-tracer]]
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==== Transport tracer
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The transport layer has a dedicated tracer logger which, when activated, logs incoming and out going requests. The log can be dynamically activated
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by setting the level of the `org.elasticsearch.transport.TransportService.tracer` logger to `TRACE`:
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[source,console]
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--------------------------------------------------
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PUT _cluster/settings
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{
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"transient" : {
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"logger.org.elasticsearch.transport.TransportService.tracer" : "TRACE"
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}
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}
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--------------------------------------------------
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You can also control which actions will be traced, using a set of include and exclude wildcard patterns. By default every request will be traced
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except for fault detection pings:
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[source,console]
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--------------------------------------------------
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PUT _cluster/settings
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{
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"transient" : {
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"transport.tracer.include" : "*",
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"transport.tracer.exclude" : "internal:coordination/fault_detection/*"
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}
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}
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--------------------------------------------------
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