Module ngx_http_v2_module

• Known Issues
• Example Configuration
• Directives
• http2_body_preread_size
• http2_chunk_size
• http2_idle_timeout
• http2_max_concurrent_pushes
• http2_max_concurrent_streams
• http2_max_field_size
• http2_max_header_size
• http2_max_requests
• http2_push
• http2_push_preload
• http2_recv_buffer_size
• http2_recv_timeout
• Embedded Variables

The ngx_http_v2_module module (1.9.5) provides support for HTTP/2 and supersedes the ngx_http_spdy_module module.

This module is not built by default, it should be enabled with the --with-http_v2_module configuration parameter.

Known Issues

Before version 1.9.14, buffering of a client request body could not be disabled regardless of proxy_request_buffering, fastcgi_request_buffering, uwsgi_request_buffering, and scgi_request_buffering directive values.

Before version 1.19.1, the lingering_close mechanism was not used to control closing HTTP/2 connections.

Example Configuration

server {
    listen 443 ssl http2;

    ssl_certificate server.crt;
    ssl_certificate_key server.key;
}

Note that accepting HTTP/2 connections over TLS requires the “Application-Layer Protocol Negotiation” (ALPN) TLS extension support, which is available only since OpenSSL version 1.0.2. Using the “Next Protocol Negotiation” (NPN) TLS extension for this purpose (available since OpenSSL version 1.0.1) is not guaranteed to work.

Also note that if the ssl_prefer_server_ciphers directive is set to the value “on”, the ciphers should be configured to comply with RFC 7540, Appendix A black list and supported by clients.

Directives

Sets the size of the buffer per each request in which the request body may be saved before it is started to be processed.

Sets the maximum size of chunks into which the response body is sliced. A too low value results in higher overhead. A too high value impairs prioritization due to HOL blocking.

Sets the timeout of inactivity after which the connection is closed.

Limits the maximum number of concurrent push requests in a connection.

Sets the maximum number of concurrent HTTP/2 streams in a connection.

Limits the maximum size of an HPACK-compressed request header field. The limit applies equally to both name and value. Note that if Huffman encoding is applied, the actual size of decompressed name and value strings may be larger. For most requests, the default limit should be enough.

Limits the maximum size of the entire request header list after HPACK decompression. For most requests, the default limit should be enough.

Sets the maximum number of requests (including push requests) that can be served through one HTTP/2 connection, after which the next client request will lead to connection closing and the need of establishing a new connection.

Closing connections periodically is necessary to free per-connection memory allocations. Therefore, using too high maximum number of requests could result in excessive memory usage and not recommended.

Pre-emptively sends (pushes) a request to the specified uri along with the response to the original request. Only relative URIs with absolute path will be processed, for example:

http2_push /static/css/main.css;

The uri value can contain variables.

Several http2_push directives can be specified on the same configuration level. The off parameter cancels the effect of the http2_push directives inherited from the previous configuration level.

Enables automatic conversion of preload links specified in the “Link” response header fields into push requests.

Sets the size of the per worker input buffer.

Sets the timeout for expecting more data from the client, after which the connection is closed.

Embedded Variables

The ngx_http_v2_module module supports the following embedded variables:

$http2

negotiated protocol identifier: “h2” for HTTP/2 over TLS, “h2c” for HTTP/2 over cleartext TCP, or an empty string otherwise.