AssetSync and Cloudfront don't agree on what mimetype js files ought to have

[nevinera]

We suddenly realized today that our production javascript files are not being served compressed by CloudFront - when we dug in, we noticed that they were now getting the Content-Type metadata value 'application/ecmascript'. That appears to be intended - AssetSync is pulling in the mime-types gem, which is using this data to determine appropriate types.

Sadly, Cloudfront does not consider "application/ecmascript" to be a compressible content-type, and just serves those files uncompressed.

Is this something you are already aware of? What's your recommended solution? MimeTypes doesn't give any good interface for overriding known Content-Types, we're currently monkey-patching your MultiMime.fetch method and intercepting requests about the js extension.

[PikachuEXE]

It seems there are several types matched by the extension name
Let me add an option to allow overriding file extension name to mime type mapping

[nevinera]

That sounds ideal - it's exactly what we went looking for first once we understood the problem. I'm also a little concerned about how hard it is for anyone to notice that they're being affected, but I don't have any good answers for that in mind :-\

[PikachuEXE]

@nevinera
Please take a look at #374 to see if it looks fine for you :)