gzip middleware

[yogthos]

No description provided.

[rutchkiwi]

that was fast! Thanks a lot for this.

I had a look through it now. I'm having quite a hard time understanding things once inside the undertow java world. Things I noticed:

1. gzip-deflate-level - It looks to me like it doesn't actually set the compression level. It looks to me like it's setting a "priority", which as I understand it is something to do with picking which compression to use, in case both deflate and gzip is used - like in the headers gzip;q=0.8, deflate;q=0.9. Which, if I'm correct, means that it should likely not be exposed to the users of the library. (source: https://stackoverflow.com/questions/28295752/compressing-undertow-server-responses)
2. This compresses all responses. It'd be nice to skip small ones? I believe the addEncodingHandler has another arity that lets you pass in a predicate for when to apply the handler. How that predicate works I'm not sure. AI thinks it should be like (Predicates/parse "max-content-size[1]") but haven't verified that.
3. In a similar vein, it'd be nice to skip gzipping for jpegs etc, that are already compressed. But on the other hand I don't think any of the ring middlewares for gzipping handles this either, so could definitely be skipped. I don't know how you'd implement such a check.

[rutchkiwi]

Digging a bit more I think a predicate like this should do the trick:

(Predicates/parse "max-content-size(1) and regex(pattern='text/.*|application/(json|javascript|xml|.*\\\\+xml)|image/svg.*', value=%{o,Content-Type})")

• 1KB limit (IMO not worth having this user configurable)
• Compressed: application/json, text/html, text/css, text/csv, text/xml, application/xml, application/*+xml, application/javascript, image/svg+xml
• Not compressed: image/jpeg, image/png, video/*, application/pdf etc

[yogthos]

Yeah, looks like I misread the gzip-deflate-level bit, just pushed up an update that should do the trick and handle the predicates.

[rutchkiwi]

I've tested this with my actual webserver and everything works great as far as I can tell. In fact, it works greater than the ring gzip middlewares I've seen around in that images are skipped.
I only noticed a leftover doc line from previous commit.

Thanks a lot for this, you are the best @yogthos :)

[yogthos]

Awesome, glad to hear everything works, and great find that the support natively exists in Undertow. Just pushed out 1.4.3 with the update. 🎉