Support HTTP gzip compression in internal Portainer server

[hhromic]

Is your feature request related to a problem? Please describe.

There is no way to configure HTTP gzip compression for the internal Portainer server.

Portainer currently is not using HTTP gzip compression:

$ curl -H "Accept-Encoding: gzip" -I https://my-portainer-instance:9000
HTTP/2 200
accept-ranges: bytes
cache-control: max-age=31536000
content-type: text/html; charset=utf-8
last-modified: Thu, 19 Mar 2020 22:46:17 GMT
x-content-type-options: nosniff
x-xss-protection: 1; mode=block
content-length: 23032
date: Mon, 23 Mar 2020 15:41:09 GMT

There is no Content-Encoding: gzip header indicating that compression was active.

Describe the solution you'd like

I would like a command-line switch to enable HTTP gzip compression for the internal Portainer server, for example --enable-compression.

Additional context

HTTP gzip compression is a standard mechanism to improve peformance by compression text-content transferred between the HTTP server and client. In other software that implements HTTP gzip compression I can easily observe faster loading times within the UI, for example Grafana or Artifactory.

It looks like the Go's http package does support compression already, so it should not be that complicated to bring to Portainer.

[hhromic]

Gist with a potential implementation for this feature request: https://gist.github.com/CJEnright/bc2d8b8dc0c1389a9feeddb110f822d7

StackOverflow answer with a similar implementation: https://stackoverflow.com/a/50898293

[deviantony]

Sounds cool @hhromic

Keen to write a first draft of implementation that we can discuss?

[hhromic]

Okay, I'll try to put sometihng together soon. Thanks for supporting!

[deviantony]

Sounds great, thanks !

[hhromic]

Hello @deviantony , @itsconquest , @ncresswell !
I started working on the HTTP gzip compression feature for Portainer (sorry for the long delay, been quite busy at work).

After researching I found a very mature (i.e. includes tests) Go library from NYtimes implementing the required functionality already: https://github.com/nytimes/gziphandler

I'm putting together a prototype for Portainer and using this library makes it very simple :)

So I'm wondering if it is okay to use third-party libraries such as this one? The license of the NYtimes library is Apache-2.0. I understand Portainer uses the zlib license but I'm not very versed on licensing so your advise is highly appreciated. Thanks!

[ghost]

@deviantony thoughts on this?

[deviantony]

Sorry missed the notification !

@hhromic it is ok to use third-party libraries yes ! Just make sure that it can be added through go modules.

[hhromic]

Created a PR implementing this functionality now. Looking forward for feedback :)