HTTP/2 implementation

The default implementation for HTTP/2 is available as a plugin (JAR download).

Configuration

Plugin Configuration Object

Configuration ID: http2

Name	Type	Description	Required	Default value
enable	boolean	Whether HTTP/2 support should be enabled by registering the "h2" TLS ALPN option (cannot change during runtime).	no	true

HTTP Engine Configuration Object

Configuration ID: HTTP2

All common HTTP engine parameters except requestTimeout are supported (see configuration file options), in addition to the ones listed below.

Name	Type	Description	Required	Default value
maxFrameSize	number	The maximum HTTP/2 frame payload size in bytes (HTTP/2 setting: MAX_FRAME_SIZE).	no	16384 (http/2 default)
maxDynamicTableSize	number	The maximum size in bytes of the HPACK dynamic table used by the decoder (HTTP/2 setting: HEADER_TABLE_SIZE).	no	4096 (http/2 default)
initialWindowSize	number	The initial flow control window size in bytes (HTTP/2 setting: INITIAL_WINDOW_SIZE).	no	65535 (http/2 default)
maxConcurrentStreams	number	The maximum number of concurrent streams (HTTP/2 setting: MAX_CONCURRENT_STREAMS).	no	100
useHuffmanEncoding	boolean	Whether to compress header strings with Huffman Coding.	no	true
closeWaitTimeout	number	The close-wait timeout for closed streams in seconds.	no	5
disablePromiseRequestLog	boolean	Disable request log of server push requests.	no	value of disableDefaultRequestLog

Upstream server protocol configuration

To actually enable proxying HTTP/2, the upstream server must support HTTP/2 and be marked as such in the configuration.

With the default configuration of a single upstream server, this is done by adding the string "http/2" to the array upstreamServerProtocols in the proxy configuration. If a plugin is used that may select a different upstream server, the configuration is likely also different (see the respective plugin documentation on how to add "http/2" as a supported protocol).

Before version 3.10.1, if an upstream server is selected that is not marked as supporting HTTP/2, but the client is using HTTP/2, a stream error with error code HTTP_1_1_REQUIRED is returned to the client; modern browsers will retry the request with HTTP/1.1 in that case. Since 3.10.1, the request will be converted to HTTP/1.1 and proxied to the upstream server, while communication to the client will continue over HTTP/2 (conversion the other way around or to a different protocol also works). In both cases, the HTTP/1.1 implementation is required.