Apache Module mod_h2

Available Languages: en

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Description:	Support for the HTTP/2 transport layer
Status:	Extension
Module Identifier:	h2_module
Source File:	mod_h2.c

Summary

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

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

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Comments

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H2Direct Directive

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Description:	H2 Direct Protocol Switch
Syntax:	`H2Direct on\|off`
Default:	`H2Direct on (for non TLS)`
Context:	server config, virtual host
Status:	Extension
Module:	mod_h2

- 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

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H2MaxSessionStreams Directive

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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_h2

- 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

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H2MaxWorkerIdleSeconds Directive

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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_h2

- 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

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H2MaxWorkers Directive

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Description:	Maximum number of worker threads to use per child process.
Syntax:	`H2MaxWorkers n`
Context:	server config
Status:	Extension
Module:	mod_h2

- 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_h2 will chose a value suitable for the mpm - module loaded. -

Example

H2MaxWorkers 20

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H2MinWorkers Directive

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Description:	Minimal number of worker threads to use per child process.
Syntax:	`H2MinWorkers n`
Context:	server config
Status:	Extension
Module:	mod_h2

- 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_h2 will chose a value suitable for the mpm - module loaded. -

Example

H2MinWorkers 10

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H2SerializeHeaders Directive

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Description:	Serialize Request/Resoonse Processing Switch
Syntax:	`H2SerializeHeaders on\|off`
Default:	`H2SerializeHeaders off`
Context:	server config, virtual host
Status:	Extension
Module:	mod_h2

- 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

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H2SessionExtraFiles Directive

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Description:	Number of Extra File Handles
Syntax:	`H2SessionExtraFiles n`
Default:	`H2SessionExtraFiles 5`
Context:	server config, virtual host
Status:	Extension
Module:	mod_h2

- 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

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H2StreamMaxMemSize Directive

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Description:	Maximum amount of output data buffered per stream.
Syntax:	`H2StreamMaxMemSize bytes`
Default:	`H2StreamMaxMemSize 65536`
Context:	server config, virtual host
Status:	Extension
Module:	mod_h2

- 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

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H2WindowSize Directive

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Description:	Size of Stream Window for upstream data.
Syntax:	`H2WindowSize bytes`
Default:	`H2WindowSize 65536`
Context:	server config, virtual host
Status:	Extension
Module:	mod_h2

- 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

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Comments

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