Missing gzip_type directive causes most resources to remain uncompressed

[s7m4b4]

I noticed when deploying this at my org that a lot of files remain uncompressed. By default Nginx will only include filetype text/html (see here). By not defining any additional types, most of the big resource files will remain uncompressed (JS/CSS).

Atlassian advised me that the following are the resource types Jira will natively compress if enabled (which I've replicated in Nginx) -
gzip_types text/xml text/plain text/javascript text/css application/javascript application/x-javascript application/xml application/xhtml application/xhtml+xml application/json;

Below is a comparison for a batch.js load on a board (not a vanilla Jira instance so don't mind the bloated filesize).
The comparison was made using curl with the Accept-Encoding on/off.
e.g.
curl -kso /dev/null JIRA_URL/batch.js
curl -kso /dev/null -H "Accept-Encoding: gzip" JIRA_URL/batch.js

gzip_types disabled -
Uncompressed size : 11.05 MiB
Compressed size : 11.05 MiB

gzip_types enabled -
Uncompressed size : 11.05 MiB
Compressed size : 3.34 MiB

Happy to make a PR if this is correct.
** Disclaimer - I'm not a Nginx expert, and may be wrong in my assertions/testing 😄 .

[Bonn93]

Makes sense, feel free to make a PR for others to reference. :)