Enables gzip compression for common mime types in nginx

nginx-gzip.conf

# most people include something like this. don't.
# check your default nginx.conf, it's already covered in a much better way.
#gzip_disable "MSIE [1-6]\.(?!.*SV1)";

# compress proxied requests too.
# it doesn't actually matter if the request is proxied, we still want it compressed.
gzip_proxied any;

# a pretty comprehensive list of content mime types that we want to compress
# there's a lot of repetition here because different applications might use different
# (and possibly non-standard) types. we don't really care, we still want them included
# don't include text/html -- it is always included anyway
gzip_types
	text/css
	text/plain
	text/javascript
	application/javascript
	application/json
	application/x-javascript
	application/xml
	application/xml+rss
	application/xhtml+xml
	application/x-font-ttf
	application/x-font-opentype
	application/vnd.ms-fontobject
	image/svg+xml
	image/x-icon
	application/rss+xml
	application/atom_xml;

# increase the compression level, at the expense of additional CPU
# cpu cycles are cheap virtually everywhere now, bandwidth not nearly as much
gzip_comp_level 9;

# the default is to gzip only HTTP 1.1 requests
# we want to gzip http 1.0 requests, too, so lower the level required
gzip_http_version 1.0;

# set the Vary: Accept-Encoding header to force proxies to store compressed and uncompressed versions
# per the nginx docs, a bug in IE 4 - 6 will cause them to not cache anything with this on
# most people aren't going to care about ie 6 anymore, but keep that in mind
gzip_vary on;

# increase the size of the buffers which hold responses to make sure larger content can be compressed too
# this means there are 16 buffers and they can each hold 8k
# if you serve a lot of ridiculously large text (like combined CSS) you might consider upping this slightly
gzip_buffers 16 8k;

# up the minimum length a little to account for gzip overhead
# this means anything smaller than 50 bytes won't be compressed.
# the default is 20 bytes, which is sooo tiny it's a waste to compress
gzip_min_length 50;