Meteor Auto-compress interfering with Brotli enabled nginx front-end proxy

[georgyberdyshev]

Hello @benjamn,

the Auto-compress feature of Meteor currently uses gzip compression and is enabled by default.
https://github.com/meteor/meteor/blob/release-1.8.1/packages/webapp/webapp_server.js#L822

When using a front-end proxy, such as nginx, it is not possible to use a different Content-Encoding such as Brotli, because the files are already gzip encoded.

I would like to discuss the possibility to introduce a new environment variable, that allows disabling the Auto-compress feature:
METEOR_DISABLE_AUTO_COMPRESS=1

The implementation is in PR: #10378

1) Running Meteor with --production flag:
gzip is used for Content-Encoding.

2) Running Meteor with --production flag behind nginx proxy with Brotli enabled:
Mixed Content-Encoding with gzip and br. The gzip encoded files cannot be encoded to Brotli.

3) Running patched Meteor with --production flag behind nginx proxy with Brotli enabled:
Only Brotli is used for Content-Encoding. nginx takes care of encoding the uncompressed files to Brotli.

Related work on Brotli support
Currently Node.js is working actively on adding Brotli compression to core:
nodejs/node#20458
nodejs/node#18964

There were some discussions in https://github.com/expressjs/compression to support Brotli compression, that were not further pursued.

Brotli browser support: https://caniuse.com/#feat=brotli

Reasoning for environment variable
Adding an environment variable to disable Auto-compress will allow to use Brotli compression through a front-end proxy and provide better compression ratio than gzip.

Some tests with my PR (#10378)

Project	gzip	brotli	br (lvl 11)	decrease	decrease (br lvl 11)
minimal	16.2	15.2	14	-6.17%	-13.58%
bare	65.3	61	55.8	-6.58%	-14.55%
full	130	122	112	-6.15%	-13.85%
react	106	99.1	90.6	-6.51%	-14.53%
angular	255	233	210	-8.63%	-17.64%
apollo	385	351	315	-8.83%	-18.18%

Note:

• size in KB
• Brotli default is level 6 (ngx_brotli levels: 0-11)
• Tested on modern browser bundle with --production flag
• angular: https://github.com/Urigo/angular-meteor/tree/master/examples/MeteorCLI/all-in-one
• apollo: https://github.com/Urigo/angular-meteor/tree/master/examples/apollo

Test environment:
Ubuntu 18.04
nginx-1.15.7
brotli: 1.0.3-1ubuntu1.2
ngx_brotli: https://github.com/eustas/ngx_brotli

Thanks, Georgy