New javascript/css files are not loaded because index.html is cached

[runephilosof-karnovgroup]

indexHTML should not be cached with a long expiry.
index.html references which version of the javascript and css files should be loaded.
So when index.html is cached with a long max-age the browser will not notice when it is time to load new javascript/css.

woodpecker/server/web/web.go

Line 176 in 6d86ec7

c.Writer.Header().Set("Cache-Control", "public, max-age=31536000")

Users need to reload the page to get the new js/css files. And even worse, if they do that while on /user for instance, the browser will only cache the new js/css files when you load woodpecker on /user next time. If you go to /repos or /, your browser will still have cached the old index file for those endpoints...

[runephilosof-karnovgroup]

Recently experienced problems with outdated javascript code again in #2821 (comment)

[qwerty287]

Is there a way to use the etag we add as header here? (Md5 of server startup time). I.e. always reload the index if this has changed?

[runephilosof-karnovgroup]

If Cache-Control is set to max-age=0, then etag will be used.
But this is only part of the problem.
Since a lot of the pages changes are within the spa, then the index.html won't get loaded, just new json responses.
So the server should probably set a header for the json responses with its version, to let the frontend detect whether it is outdated.
Or the spa should poll /version every minute or so.

[qwerty287]

If index.html is reloaded, also every spa file that has been changed will be reloaded, because they have a hash in their filename that changes in this case.

[runephilosof-karnovgroup]

But index.html is not reloaded, because max-age=31536000.
So the end user won't get the new version unless they manually click reload in the browser (it just happened to me again, when upgrading to v2.0.0).

It is fairly easy to reproduce.

1. Install next on the server.
2. Visit in a browser.
3. Change server to v2.0.0.
4. Click around in the browser
5. Open a new window, go to your woodpecker installation

Actual:
Version still shows next in the top left

Expected:
Version shows v2.0.0 in the top left

[qwerty287]

Would this issue be solved by just removing the max-age and only set etag?

[runephilosof-karnovgroup]

max-age=0, or a low number.
This will affect how many requests the server receives for assets (those requests will have If-None-Match: <etag>, so probably easily processed, but they will still have to be processed).
Assets which have hashes, timestamps or similar in the request, can be cached a long time.

Some assets don't have cache busting hashes/timestamps, like the favicon. So setting max-age=0 will make it easier to update those as well. Although, adding cache busting to those assets will be even better.

[runephilosof-karnovgroup]

It seems the etag is only set. It is never checked by the server when the browser sends
If-None-Match: <etag>.
Anyway, I have made a PR for setting the max-age: 60 when it is the index.html.