static css chunks served with maxage=0

[Enalmada]

Bug report

Describe the bug

static css files appear to be served with sub-optimal cache-control:

/_next/static/css/commons.4e4de3e2.chunk.css
/_next/static/css/styles.4015be53.chunk.css
served with:
cache-control: public, max-age=0

I am new to Next.js behavior so apologies if this is not really a bug and css chunk shouldn't be served max-age=31536000, immutable for some reason. I just assume that the chunk hash (commons.4e4de3e2.chunk.css) ensure these things could/should be immutable but I am ready to be educated.

To Reproduce

Steps to reproduce the behavior, please provide code snippets or a repository:

1. Go to any next.js page in chrome right click on any element and inspect element
2. Right click on any element and inspect element
3. Look at the network tab and click on a /_next/static/css
4. See cache-control is "public, max-age=0"

Expected behavior

I expect them to be served with "cache-control: public, max-age=31536000, immutable" like everything else in the /_next/static seems to be served with.

System information

• OS: [e.g. macOS, Windows]
• Browser: chrome
• Version of Next.js: 7.0.2

Additional context

You can see this here: https://client.gelltest.com/
I can provide this sample repo if this for some reason isn't immediately and obviously reproducible.
(Identified after looking into css due to this comment: https://spectrum.chat/?t=9f9f43b8-ec8b-45e5-a8e3-5b57a62e9e67)

[timneutkens]

Answered here: https://spectrum.chat/thread/9f9f43b8-ec8b-45e5-a8e3-5b57a62e9e67?m=MTUzOTc3Mjc4NTQyOQ==

[Enalmada]

@timneutkens I tried to start a pull request changing css-loader-config.js lines to static/chunks (per spectrum suggestion above) but when testing, I see that the css files are being fetched twice, once from static/css and static/chunks directory.

I can't quite tell what is causing the duplicate. Perhaps something in Head when fetching chunks and css needs to change too to filter out one or the other?

[lennerd]

Sidenote: the max-age=0 is also set for all other assets in the static folder.

[lennerd]

Sorry, just realised this is intentional: #1791

[Enalmada]

Should I move this to next-plugins?

[Enalmada]

@quietshu I am trying to make a middleware for the next.js community (https://github.com/Enalmada/next-preload-headers) that is useless without this fix. @timneutkens implied that it might be an easy fix just changing static/css to static/chunks...I tried but got some strange behavior I noted above. I am hoping that with your superior experience you might be able to immediately tell what additional thing needs to be done to fix this for good.

[Enalmada]

I believe I have solved this bug with the following pull requests. I don't completely understand what I am doing but because this bug is hurting me I am trying to do my best. Please review:
#5675
vercel/next-plugins#335