Portage writes a compressed copy of 'Packages' index file.

This behaviour is enabled by FEATURES="compress-index". The
resulting file is 'Packages.gz' and its modification time will
match that of 'Packages'.

Web-servers use that copy to avoid repeated on-the-fly compression.

In order to re-use 'atomic_ofstream' usage of 'codecs.zlib_codec'
has been considered and discarded, because 'GzipFile' yields
smaller files. (According to Mark's tests 62% smaller.)

Example usage, Nginx:

  location =/Packages {
    gzip_static on;
    default_type text/plain;
  }

Apache httpd (use with caution):

  RewriteRule ^(.*)/Packages$ $1/Packages.gz [T=text/plain,E=GZIP:gzip,L]
  <FilesMatch "Packages\.gz$">
    Header set Content-Encoding gzip
  </FilesMatch>

1 files changed, 7 insertions, 0 deletions

diff --git a/man/make.conf.5 b/man/make.conf.5
index 876a8a330..02cc8098d 100644
--- a/man/make.conf.5
+++ b/man/make.conf.5
@@ -268,6 +268,13 @@ space.  Make sure you have built both binutils and gdb with USE=zlib
 support for this to work.  See \fBsplitdebug\fR for general split debug
 information (upon which this feature depends).
 .TP
+.B compress\-index
+If set then a compressed copy of 'Packages' index file will be written.
+This feature is intended for Gentoo binhosts using certain webservers
+(such as, but not limited to, Nginx with gzip_static module) to avoid
+redundant on\-the\-fly compression.  The resulting file will be called
+'Packages.gz' and its modification time will match that of 'Packages'.
+.TP
 .B config\-protect\-if\-modified
 This causes the \fBCONFIG_PROTECT\fR behavior to be skipped for files
 that have not been modified since they were installed. This feature is