Apache Module mod_http2

Available Languages: en

+ + + +

Description:	Support for the HTTP/2 transport layer
Status:	Extension
Module Identifier:	h2_module
Source File:	mod_http2.c

Summary

+ +

This module provides HTTP/2 (RFC 7540) support for the Apache + HTTP Server.

+ +

This module relies on libnghttp2 + to provide the core http/2 engine.

+ +

Comments

+ +

H2Direct Directive

+ + + + + + + +

Description:	H2 Direct Protocol Switch
Syntax:	`H2Direct on\|off`
Default:	`H2Direct on (for non TLS)`
Context:	server config, virtual host
Status:	Extension
Module:	mod_http2

+ This directive toggles the usage of the HTTP/2 Direct Mode. This + should be used inside a + <VirtualHost> + section to enable direct HTTP/2 communication for that virtual host. + Direct communication means that if the first bytes received by the + server on a connection match the HTTP/2 preamble, the HTTP/2 + protocol is switched to immediately without further negotiation. + This mode falls outside the RFC 7540 but has become widely implemented + as it is very convenient for development and testing. + By default the direct HTTP/2 mode is enabled. +

Example

H2Direct on

+ +

H2MaxSessionStreams Directive

+ + + + + + + +

Description:	Maximum number of active streams per HTTP/2 session.
Syntax:	`H2MaxSessionStreams n`
Default:	`H2MaxSessionStreams 100`
Context:	server config, virtual host
Status:	Extension
Module:	mod_http2

+ This directive sets the maximum number of active streams per HTTP/2 session (e.g. connection) + that the server allows. A stream is active if it is not idle or + closed according to RFC 7540. +

Example

H2MaxSessionStreams 20

+ +

H2MaxWorkerIdleSeconds Directive

+ + + + + + + +

Description:	Maximum number of seconds h2 workers remain idle until shut down.
Syntax:	`H2MaxWorkerIdleSeconds n`
Default:	`H2MaxWorkerIdleSeconds 600`
Context:	server config
Status:	Extension
Module:	mod_http2

+ This directive sets the maximum number of seconds a h2 worker may + idle until it shuts itself down. This only happens while the number of + h2 workers exceeds H2MinWorkers. +

Example

H2MaxWorkerIdleSeconds 20

+ +

H2MaxWorkers Directive

+ + + + + + +

Description:	Maximum number of worker threads to use per child process.
Syntax:	`H2MaxWorkers n`
Context:	server config
Status:	Extension
Module:	mod_http2

+ This directive sets the maximum number of worker threads to spawn + per child process for HTTP/2 processing. If this directive is not used, + mod_http2 will chose a value suitable for the mpm + module loaded. +

Example

H2MaxWorkers 20

+ +

H2MinWorkers Directive

+ + + + + + +

Description:	Minimal number of worker threads to use per child process.
Syntax:	`H2MinWorkers n`
Context:	server config
Status:	Extension
Module:	mod_http2

+ This directive sets the minimum number of worker threads to spawn + per child process for HTTP/2 processing. If this directive is not used, + mod_http2 will chose a value suitable for the mpm + module loaded. +

Example

H2MinWorkers 10

+ +

H2SerializeHeaders Directive

+ + + + + + + +

Description:	Serialize Request/Resoonse Processing Switch
Syntax:	`H2SerializeHeaders on\|off`
Default:	`H2SerializeHeaders off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_http2

+ This directive toggles if HTTP/2 requests shall be serialized in + HTTP/1.1 format for processing by httpd core or if + received binary data shall be passed into the request_recs + directly. +

+ Serialization will lower performance, but gives more backward + compatibility in case custom filters/hooks need it. +

Example

H2SerializeHeaders on

+ +

H2SessionExtraFiles Directive

+ + + + + + + +

Description:	Number of Extra File Handles
Syntax:	`H2SessionExtraFiles n`
Default:	`H2SessionExtraFiles 5`
Context:	server config, virtual host
Status:	Extension
Module:	mod_http2

+ This directive sets maximum number of extra file handles + a HTTP/2 session is allowed to use. A file handle is counted as + extra when it is transfered from a h2 worker thread to + the main HTTP/2 connection handling. This commonly happens when + serving static files. +

+ Depending on the processing model configured on the server, the + number of connections times number of active streams may exceed + the number of file handles for the process. On the other hand, + converting every file into memory bytes early results in too + many buffer writes. This option helps to mitigate that. +

+ The number of file handles used by a server process is then in + the order of: +

(h2_connections * extra_files) + (h2_max_worker)

Example

H2SessionExtraFiles 10

+ +

H2StreamMaxMemSize Directive

+ + + + + + + +

Description:	Maximum amount of output data buffered per stream.
Syntax:	`H2StreamMaxMemSize bytes`
Default:	`H2StreamMaxMemSize 65536`
Context:	server config, virtual host
Status:	Extension
Module:	mod_http2

+ This directive sets the maximum number of outgoing data bytes buffered in memory + for an active streams. This memory is not allocated per stream as such. Allocations + are counted against this limit when they are about to be done. Stream processing + freezes when the limit has been reached and will only continue when buffered data + has been sent out to the client. +

Example

H2StreamMaxMemSize 128000

+ +

H2WindowSize Directive

+ + + + + + + +

Description:	Size of Stream Window for upstream data.
Syntax:	`H2WindowSize bytes`
Default:	`H2WindowSize 65536`
Context:	server config, virtual host
Status:	Extension
Module:	mod_http2

+ This directive sets the size of the window that is used for flow control + from client to server and limits the amount of data the server has to buffer. + The client will stop sending on a stream once the limit has been reached until + the server announces more available space (as it has processed some of the data). +

+ This limit affects only request bodies, not its meta data such as headers. Also, + it has no effect on response bodies as the window size for those are managed + by the clients. +

Example

H2WindowSize 128000

+ +

Comments

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