WebServer Configuration

WebServer Configuration: Configure the WebServer either programmatically, or by the Helidon configuration framework.

Configuring the WebServer in your code

The easiest way to configure the WebServer is in your application code.

WebServer webServer = WebServer.builder()
      .bindAddress(InetAddress.getLocalHost())
      .port(8080)
      .build();

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Configuring the WebServer in a configuration file

You can also define the configuration in a file.

WebServer configuration file application.yaml

server:
  port: 8080
  bind-address: "0.0.0.0"

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Then, in your application code, load the configuration from that file.

WebServer initialization using the application.yaml file located on the classpath

Config config = Config.create(); 
WebServer webServer = WebServer.create(routing, config.get("server"));

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application.yaml is a default configuration source loaded when YAML support is on classpath, so we can just use Config.create()
Server expects the configuration tree located on the node of server

Configuration options

See all configuration options here.

Available socket configuration options:

Configuration key	Default value	Java type	Description
`port`		int	Port to open server socket on, defaults to an available ephemeral port
`bind-address`	all local addresses	String	Address to listen on (may be an IPV6 address as well)
`backlog`	`1024`	int	Maximum length of the queue of incoming connections on the server socket.
`max-header-size`	`16384`	int	Maximal number of bytes of all header values combined. Returns `400` if headers are bigger
`max-initial-line-length`	`4096`	int	Maximal number of characters in the initial HTTP line. Returns `400` if line is longer
`timeout-millis`	no timeout	long	Server socket timeout.
`receive-buffer-size`	implementation default	int	Proposed value of the TCP receive window that is advertised to the remote peer on the server socket.
`name`	`@default` for default socket	String	Name used for named sockets, to support additional server sockets (and their named routing)
`enabled`	`true`	boolean	A socket can be disabled through configuration, in which case it is never opened
`max-chunk-size`	`8192`	int	Maximal size of a chunk to read from incoming requests
`max-payload-size`	`-1`	long	Maximal size of a request payload in bytes. If exceeded a 413 error is returned. Negative value means no limit.
`connection-idle-timeout`	`0`	int	Timeout seconds after which any idle connection will be automatically closed. 0 means no timeout.
`backpressure-buffer-size`	long	`5242880`	Set a maximum length of the unflushed response data sending buffer can keep without applying backpressure. Depends on `backpressure-policy` what happens if max buffer size is reached.	Default is `510241024` - 5Mb
`backpressure-policy`	String	`LINEAR`	Sets the strategy for applying backpressure to the reactive stream of response data.	* LINEAR - Data chunks are requested one-by-one after previous data chunk has been written to Netty’s buffer, when `backpressure-buffer-size` watermark is reached, new chunks are not requested until buffer size decrease under the watermark value. * PREFETCH - After first data chunk arrives, expected number of chunks needed to fill the buffer up to watermark is calculated and requested. * AUTO_FLUSH - Data are requested one-by-one, in case buffer reaches watermark, no other data is requested and extra flush is initiated. * UNBOUNDED - No backpressure is applied, Long.MAX_VALUE(unbounded) is requested from upstream.	Default is `LINEAR`
`validate-headers`	`true`	boolean	Whether to validate header names, if they contain illegal characters.
`initial-buffer-size`	`128`	int	Initial size of buffer used to parse HTTP line and headers
`tls`		Object	Configuration of TLS, please see our TLS example in repository
`requested-uri-discovery.enabled`	boolean	`true` if `types` or `trusted-proxies` is set; `false` otherwise`	Sets whether requested URI discovery is enabled for the socket.
`requested-uri-discovery.trusted-proxies`	`AllowList`		Assigns the settings governing the acceptance and rejection of forwarded headers from incoming requests to this socket. This setting automatically enables discovery for the socket.
`requested-uri-discovery.types`	`(FORWARDED, X_FORWARDED, HOST)` (See `RequestedUriDiscoveryType`)	`FORWARDED if discovery is enabled; none otherwise`	Assigns the front-end URI discovery type(s) this socket should use. This setting automatically enables discovery for the socket.