120 lines
5.7 KiB
Plaintext
120 lines
5.7 KiB
Plaintext
[[modules-http]]
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== HTTP
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The http module allows to expose *Elasticsearch* APIs
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over HTTP.
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The http mechanism is completely asynchronous in nature, meaning that
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there is no blocking thread waiting for a response. The benefit of using
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asynchronous communication for HTTP is solving the
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http://en.wikipedia.org/wiki/C10k_problem[C10k problem].
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When possible, consider using
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http://en.wikipedia.org/wiki/Keepalive#HTTP_Keepalive[HTTP keep alive]
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when connecting for better performance and try to get your favorite
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client not to do
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http://en.wikipedia.org/wiki/Chunked_transfer_encoding[HTTP chunking].
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[float]
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=== Settings
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The settings in the table below can be configured for HTTP. Note that none of
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them are dynamically updatable so for them to take effect they should be set in
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`elasticsearch.yml`.
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[cols="<,<",options="header",]
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|=======================================================================
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|Setting |Description
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|`http.port` |A bind port range. Defaults to `9200-9300`.
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|`http.publish_port` |The port that HTTP clients should use when
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communicating with this node. Useful when a cluster node is behind a
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proxy or firewall and the `http.port` is not directly addressable
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from the outside. Defaults to the actual port assigned via `http.port`.
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|`http.bind_host` |The host address to bind the HTTP service to. Defaults to `http.host` (if set) or `network.bind_host`.
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|`http.publish_host` |The host address to publish for HTTP clients to connect to. Defaults to `http.host` (if set) or `network.publish_host`.
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|`http.host` |Used to set the `http.bind_host` and the `http.publish_host` Defaults to `http.host` or `network.host`.
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|`http.max_content_length` |The max content of an HTTP request. Defaults to
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`100mb`. If set to greater than `Integer.MAX_VALUE`, it will be reset to 100mb.
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|`http.max_initial_line_length` |The max length of an HTTP URL. Defaults
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to `4kb`
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|`http.max_header_size` | The max size of allowed headers. Defaults to `8kB`
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|`http.compression` |Support for compression when possible (with
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Accept-Encoding). Defaults to `true`.
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|`http.compression_level` |Defines the compression level to use for HTTP responses. Valid values are in the range of 1 (minimum compression)
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and 9 (maximum compression). Defaults to `3`.
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|`http.cors.enabled` |Enable or disable cross-origin resource sharing,
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i.e. whether a browser on another origin can execute requests against
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Elasticsearch. Set to `true` to enable Elasticsearch to process pre-flight
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https://en.wikipedia.org/wiki/Cross-origin_resource_sharing[CORS] requests.
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Elasticsearch will respond to those requests with the `Access-Control-Allow-Origin` header
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if the `Origin` sent in the request is permitted by the `http.cors.allow-origin`
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list. Set to `false` (the default) to make Elasticsearch ignore the `Origin`
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request header, effectively disabling CORS requests because Elasticsearch will
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never respond with the `Access-Control-Allow-Origin` response header. Note that
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if the client does not send a pre-flight request with an `Origin` header or it
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does not check the response headers from the server to validate the
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`Access-Control-Allow-Origin` response header, then cross-origin security is
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compromised. If CORS is not enabled on Elasticsearch, the only way for the client
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to know is to send a pre-flight request and realize the required response headers
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are missing.
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|`http.cors.allow-origin` |Which origins to allow. Defaults to no origins
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allowed. If you prepend and append a `/` to the value, this will
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be treated as a regular expression, allowing you to support HTTP and HTTPs.
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for example using `/https?:\/\/localhost(:[0-9]+)?/` would return the
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request header appropriately in both cases. `*` is a valid value but is
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considered a *security risk* as your Elasticsearch instance is open to cross origin
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requests from *anywhere*.
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|`http.cors.max-age` |Browsers send a "preflight" OPTIONS-request to
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determine CORS settings. `max-age` defines how long the result should
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be cached for. Defaults to `1728000` (20 days)
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|`http.cors.allow-methods` |Which methods to allow. Defaults to
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`OPTIONS, HEAD, GET, POST, PUT, DELETE`.
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|`http.cors.allow-headers` |Which headers to allow. Defaults to
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`X-Requested-With, Content-Type, Content-Length`.
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|`http.cors.allow-credentials` | Whether the `Access-Control-Allow-Credentials`
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header should be returned. Note: This header is only returned, when the setting is
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set to `true`. Defaults to `false`
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|`http.detailed_errors.enabled` |Enables or disables the output of detailed error messages
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and stack traces in response output. Note: When set to `false` and the `error_trace` request
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parameter is specified, an error will be returned; when `error_trace` is not specified, a
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simple message will be returned. Defaults to `true`
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|`http.pipelining` |Enable or disable HTTP pipelining, defaults to `true`.
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|`http.pipelining.max_events` |The maximum number of events to be queued up in memory before a HTTP connection is closed, defaults to `10000`.
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|=======================================================================
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It also uses the common
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<<modules-network,network settings>>.
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[float]
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=== Disable HTTP
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The http module can be completely disabled and not started by setting
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`http.enabled` to `false`. Elasticsearch nodes (and Java clients) communicate
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internally using the <<modules-transport,transport interface>>, not HTTP. It
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might make sense to disable the `http` layer entirely on nodes which are not
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meant to serve REST requests directly. For instance, you could disable HTTP on
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<<modules-node,data-only nodes>> if you also have
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<<modules-node,client nodes>> which are intended to serve all REST requests.
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Be aware, however, that you will not be able to send any REST requests (eg to
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retrieve node stats) directly to nodes which have HTTP disabled.
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