Mod deflate » History » Revision 37
Revision 36 (gstrauss, 2021-06-21 10:45) → Revision 37/43 (gstrauss, 2021-06-22 14:29)
h2. mod_deflate mod_deflate (since lighttpd 1.4.42) enables output compression of responses. (Content-Encoding) Output compression reduces the network load and can improve the overall throughput of the webserver. All major http-clients support compression by announcing it in the Accept-Encoding header. This is used to negotiate the most suitable compression method. We support deflate, gzip, bzip2, brotli (since 1.4.56), and zstd (since 1.4.59). deflate (RFC1950, RFC1951) and gzip (RFC1952) depend on zlib. brotli (RFC7932) is supported in most popular browsers. zstd (RFC8478) zlib while bzip2 depends on libbzip2. bzip2 is only supported by lynx and some other console text-browsers, and text-browsers. brotli (RFC7932) is no longer recommended; brotli or gzip should be preferred. supported in most popular browsers. Since lighttpd 1.4.56, mod_deflate subsumes and replaces mod_compress. mod_deflate can compress static and dynamic responses, while mod_compress could compress only static files. h3. Module options: <pre> #deflate.mimetypes = ("text/") # prefix matches all text/* Content-Type responses deflate.mimetypes = ("text/html", "text/plain", "text/css", "text/javascript", "text/xml") deflate.allowed-encodings = ( "br", "gzip", "deflate" ) # "bzip2" and "zstd" also supported ## optional deflate.cache-dir = "/path/to/compress/cache" #deflate.max-compress-size = 131072 # measured in kilobytes, so 131072 indicates 128 MB #deflate.min-compress-size = 256 # measured in bytes #deflate.max-loadavg #deflate.compression-level = "3.50" #deflate.params 9 #deflate.output-buffer-size = ( # since lighttpd 1.4.60 (recommended: leave defaults unless you test your changes for positive effect) 8192 # "BROTLI_PARAM_QUALITY" => 11, # 0..11 (default is 11 (BROTLI_DEFAULT_QUALITY)) #deflate.work-block-size = 2048 # "BROTLI_PARAM_LGWIN" => 22, # 10..24 (default is 22 (BROTLI_DEFAULT_WINDOW)) #deflate.max-loadavg = "3.50" # "BROTLI_PARAM_MODE" => 0, # 0..2 (default </pre> @deflate.max-compress-size@ is 0 (BROTLI_MODE_GENERIC)) (1: BROTLI_MODE_TEXT) (2: BROTLI_MODE_FONT) the largest response size that will be compressed. # "ZSTD_c_compressionLevel" => 3, # (default @deflate.min-compress-size@ is 3 (ZSTD_CLEVEL_DEFAULT) # "ZSTD_c_strategy" => 0, # 0..9 (default the smallest response size that will be compressed. @deflate.compression-level@ is 0 (use zstd default strategy)) # "gzip.level" => 6, # 1..9 (default compression level or quality tuning for the underlying compressor. (more info: @man gzip@ (1..9); @man bzip2@ (1..9); @man -s 3brotli encode.h@ (0..11) @deflate.output-buffer-size@ is 6 (Z_DEFAULT_COMPRESSION)) a per connection buffer for compressed output, it can # help decrease the response size (fewer chunks to encode). "bzip2.blockSize100k" => 9, # 1..9 (default If it is 9 (block size 900k)) set to #) zero, a shared buffer will be used. #deflate.compression-level = 9 # deprecated; overloaded; use deflate.params (since 1.4.60) for encoder-specific values) @deflate.work-block-size@ is the number of kilobytes to compress at one time, it allows #deflate.work-block-size = 2048 # deprecated; gzip-specific; currently has no effect (unused) the webserver to do other work (network I/O) in code #deflate.output-buffer-size = 8192 # deprecated; gzip- and bzip2-specific; currently has little effect in code (due to mod_deflate not streaming partial responses) </pre> between compression. @deflate.max-loadavg@ is max system loadavg before bypassing compression (since 1.4.43) @deflate.cache-dir@ (since 1.4.56) is the location under which to store cache of compressed files. Cleaning the cache is left to the user. A cron job deleting files older than 10 days could do it: @find /path/to/compress/cache -type f -mtime +10 | xargs -r rm@ @deflate.allowed-encodings@ lists the encodings from which the server will select. Since lighttpd 1.4.60, the ordering of this list is preserved and the server selects the first encoding from this list which matches a value in the client request Accept header. @deflate.max-compress-size@ is the largest response size that will be compressed. @deflate.min-compress-size@ is the smallest response size that will be compressed. @deflate.max-loadavg@ is max system loadavg before bypassing compression (since 1.4.43) @deflate.compression-level@ (deprecated) is compression level or quality tuning for the underlying compressor. (deprecated; use deflate.params (since 1.4.60) for encoder-specific values) (more info: @man gzip@ (1..9); @man bzip2@ (1..9); @man -s 3brotli encode.h@ (0..11) h3. Known Limitations mod_deflate currently does not stream compressed content in chunks. This affects very large dynamic responses, or dynamic responses sent in chunks with large time lapses between chunks. If the entire response is not ready when the response header is sent, mod_deflate does not compress process the response. (e.g. dynamic response from backend and @server.stream-response-body@ is set > 0) While mod_deflate does not handle this use case, the backend producing the streaming response is able to apply an appropriate Content-Encoding itself (instead of mod_deflate). mod_deflate @deflate.cache-dir@, if set, contains cached output of static files, but does not cache dynamic responses unless the response contains an ETag response header. (dynamic responses, if eligible, are still compressed by mod_deflate before the response is sent to the client.) mod_deflate must be listed after mod_setenv in @server.modules@ if mod_setenv might be used to force setting "Content-Encoding" response header. h3. Content-Negotiation For selection/negotiation of pre-compressed files in the document root, e.g. main.html.br or main.html.gz when main.html is requested, use [[Docs_ModMagnet|mod_magnet]] with custom lua code for "Content-Negotiation":https://redmine.lighttpd.net/projects/lighttpd/wiki/AbsoLUAtion#Content-Negotiation