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HTTP

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HTTP

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The HTTP layer exposes Elasticsearch’s REST APIs over HTTP. Clients send HTTP requests to a node in the cluster which either handles it locally or else passes it on to other nodes for further processing using the Transport layer.

When possible, consider using HTTP keep alive when connecting for better performance and try to get your favorite client not to do HTTP chunking.

HTTP settings

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The following settings can be configured for HTTP. These settings also use the common network settings.

http.port: (Static) A bind port range. Defaults to 9200-9300.
http.publish_port: (Static) The port that HTTP clients should use when communicating with this node. Useful when a cluster node is behind a proxy or firewall and the http.port is not directly addressable from the outside. Defaults to the actual port assigned via http.port.
http.bind_host: (Static) The host address to bind the HTTP service to. Defaults to http.host (if set) or network.bind_host.
http.publish_host: (Static) The host address to publish for HTTP clients to connect to. Defaults to http.host (if set) or network.publish_host.
http.host: (Static) Used to set the http.bind_host and the http.publish_host.
http.max_content_length: (Static) Maximum size of an HTTP request body. Defaults to 100mb.
http.max_initial_line_length: (Static) Maximum size of an HTTP URL. Defaults to 4kb.
http.max_header_size: (Static) Maximum size of allowed headers. Defaults to 8kb.

http.compression

(Static) Support for compression when possible (with Accept-Encoding). If HTTPS is enabled, defaults to false. Otherwise, defaults to true.

Disabling compression for HTTPS mitigates potential security risks, such as a BREACH attack. To compress HTTPS traffic, you must explicitly set http.compression to true.

http.compression_level

(Static) Defines the compression level to use for HTTP responses. Valid values are in the range of 1 (minimum compression) and 9 (maximum compression). Defaults to 3.

http.cors.enabled: (Static) Enable or disable cross-origin resource sharing, which determines whether a browser on another origin can execute requests against Elasticsearch. Set to true to enable Elasticsearch to process pre-flight CORS requests. Elasticsearch will respond to those requests with the Access-Control-Allow-Origin header if the Origin sent in the request is permitted by the http.cors.allow-origin list. Set to false (the default) to make Elasticsearch ignore the Origin request header, effectively disabling CORS requests because Elasticsearch will never respond with the Access-Control-Allow-Origin response header.

If the client does not send a pre-flight request with an Origin header or it does not check the response headers from the server to validate the Access-Control-Allow-Origin response header, then cross-origin security is compromised. If CORS is not enabled on Elasticsearch, the only way for the client to know is to send a pre-flight request and realize the required response headers are missing.

http.cors.allow-origin: (Static) Which origins to allow. If you prepend and append a forward slash (/) to the value, this will be treated as a regular expression, allowing you to support HTTP and HTTPs. For example, using /https?:\/\/localhost(:[0-9]+)?/ would return the request header appropriately in both cases. Defaults to no origins allowed.

A wildcard (*) is a valid value but is considered a security risk, as your Elasticsearch instance is open to cross origin requests from anywhere.

http.cors.max-age: (Static) Browsers send a "preflight" OPTIONS-request to determine CORS settings. max-age defines how long the result should be cached for. Defaults to 1728000 (20 days).

http.cors.allow-methods: (Static) Which methods to allow. Defaults to OPTIONS, HEAD, GET, POST, PUT, DELETE.

http.cors.allow-headers: (Static) Which headers to allow. Defaults to X-Requested-With, Content-Type, Content-Length.

http.cors.allow-credentials: (Static) Whether the Access-Control-Allow-Credentials header should be returned. Defaults to false.

This header is only returned when the setting is set to true.

http.detailed_errors.enabled

(Static) If true, enables the output of detailed error messages and stack traces in the response output. Defaults to true.

If false, use the error_trace parameter to enable stack traces and return detailed error messages. Otherwise, only a simple message will be returned.

http.pipelining.max_events

(Static) The maximum number of events to be queued up in memory before an HTTP connection is closed, defaults to 10000.

http.max_warning_header_count

(Static) The maximum number of warning headers in client HTTP responses. Defaults to unbounded.

http.max_warning_header_size

(Static) The maximum total size of warning headers in client HTTP responses. Defaults to unbounded.

http.tcp.no_delay

(Static) Enable or disable the TCP no delay setting. Defaults to network.tcp.no_delay.

http.tcp.keep_alive

(Static) Configures the SO_KEEPALIVE option for this socket, which determines whether it sends TCP keepalive probes. Defaults to network.tcp.keep_alive.

http.tcp.keep_idle

(Static) Configures the TCP_KEEPIDLE option for this socket, which determines the time in seconds that a connection must be idle before starting to send TCP keepalive probes. Defaults to network.tcp.keep_idle, which uses the system default. This value cannot exceed 300 seconds. Only applicable on Linux and macOS, and requires Java 11 or newer.

http.tcp.keep_interval

(Static) Configures the TCP_KEEPINTVL option for this socket, which determines the time in seconds between sending TCP keepalive probes. Defaults to network.tcp.keep_interval, which uses the system default. This value cannot exceed 300 seconds. Only applicable on Linux and macOS, and requires Java 11 or newer.

http.tcp.keep_count

(Static) Configures the TCP_KEEPCNT option for this socket, which determines the number of unacknowledged TCP keepalive probes that may be sent on a connection before it is dropped. Defaults to network.tcp.keep_count, which uses the system default. Only applicable on Linux and macOS, and requires Java 11 or newer.

http.tcp.reuse_address

(Static) Should an address be reused or not. Defaults to network.tcp.reuse_address.

http.tcp.send_buffer_size

(Static) The size of the TCP send buffer (specified with size units). Defaults to network.tcp.send_buffer_size.

http.tcp.receive_buffer_size

(Static) The size of the TCP receive buffer (specified with size units). Defaults to network.tcp.receive_buffer_size.

REST request tracer

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The HTTP layer has a dedicated tracer logger which, when activated, logs incoming requests. The log can be dynamically activated by setting the level of the org.elasticsearch.http.HttpTracer logger to TRACE:

PUT _cluster/settings
{
   "transient" : {
      "logger.org.elasticsearch.http.HttpTracer" : "TRACE"
   }
}

You can also control which uris will be traced, using a set of include and exclude wildcard patterns. By default every request will be traced.

PUT _cluster/settings
{
   "transient" : {
      "http.tracer.include" : "*",
      "http.tracer.exclude" : ""
   }
}

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