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gstrauss, 2020-07-20 20:07


mod_deflate (since lighttpd 1.4.42) enables output compression (Content-Encoding) of responses.

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, and brotli. (brotli support since 1.4.56)

deflate (RFC1950, RFC1951) and gzip (RFC1952) depend on zlib while bzip2 depends on libbzip2. bzip2 is only supported by lynx and some other console text-browsers. brotli (RFC7932) is supported in most popular browsers.

Since lighttpd 1.4.56, mod_deflate subsumes and replaces mod_compress. mod_deflate differs from mod_compress in that mod_deflate can compress any output from lighttpd static or dynamic.

Module options:

#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 = ( "brotli", "gzip", "deflate" ) # "bzip2" 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.compression-level = 9
#deflate.output-buffer-size = 8192 = 2048
#deflate.max-loadavg = "3.50" 

max-compress-size is the largest response size that will be compressed.
min-compress-size is the smallest response size that will be compressed.

output-buffer-size is a per connection buffer for compressed output, it can
help decrease the response size (fewer chunks to encode). If it is set to
zero, a shared buffer will be used.

work-block-size is the number of kilobytes to compress at one time, it allows
the webserver to do other work (network I/O) in between compression.

max-loadavg is max system loadavg before bypassing compression (since 1.4.43)

Known Limitation

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 process the response. (e.g. dynamic response from backend and is set)

Updated by gstrauss over 1 year ago · 26 revisions