Missing theme-javascripts assets (http 404) on 2.8 stable

dmorlock · May 4, 2022, 3:27pm

We run into an error where the theme-javascripts seems to be missing:

$ curl https://mydomain.com | grep "theme-javascript"
<script src="/theme-javascripts/ff7f780a40bfd1e31a2cdc99c7dbc616f619d7d9.js?__ws=mydomain.com"></script>
<script src="/theme-javascripts/1bb8395b8d8d9daecdbef830d8c9418b93a7b5f9.js?__ws=mydomain.com"></script>

But when we try to access these files (in a browser with a logged in user) we get an 404 error:

Hoppla! Diese Seite existiert nicht oder ist privat.

When we check the javascript-cache, the files exist:

$ find /var/www/discourse/tmp/javascript-cache -iname 'ff7f780a40bfd1e31a2cdc99c7dbc616f619d7d9*'
/var/www/discourse/tmp/javascript-cache/ff7f780a40bfd1e31a2cdc99c7dbc616f619d7d9.js

The current workaround is to edit the custom theme by changing and saving the theme.
After 1-2 days, the problem occurs again.

We’d appreciate any help for further investigation.

Thanks,
Daniel.

david · May 4, 2022, 5:10pm

What version of Discourse are you running? We fixed a similar-sounding issue back in February:

github.com/discourse/discourse

FIX: Ensure theme JavaScript cache get consistent SHA1 digest (#15933)

committed 01:23PM - 14 Feb 22 UTC

OsamaSayegh

+6 -1

There is a couple of layers of caching for theme JavaScript in Discourse: The… first layer is the `javascript_caches` table in the database. When a theme with JavaScript files is installed, Discourse stores each one of the JavaScript files in the `theme_fields` table, and then concatenates the files, compiles them, computes a SHA1 digest of the compiled JavaScript and store the results along with the SHA1 digest in the `javascript_caches` table. Now when a request comes in, we need to render `<script>` tags for the activated theme(s) of the site. To do this, we retrieve the `javascript_caches` records of the activated themes and generate a `<script>` tag for each record. The `src` attribute of these tags is a path to the `/theme-javascripts/:digest` route which simply responds with the compiled JavaScript that has the requested digest. The second layer is a distributed cache whose purpose is to make rendering `<script>` a lot more efficient. Without this cache, we'd have to query the `javascript_caches` table to retrieve the SHA1 digests for every single request. So we use this cache to store the `<script>` tags themselves so that we only have to retrieve the `javascript_caches` records of the activated themes for the first request and future requests simply get the cached `<script>` tags. What this commit does it ensures that the SHA1 digest in the `javascript_caches` table stay the same across compilations by adding an order by id clause to the query that loads the `theme_fields` records. Currently, we specify no order when retrieving the `theme_fields` records so the order in which they're retrieved can change across compilations and therefore cause the SHA1 to change even though the individual records have not changed at all. An inconsistent SHA1 digest across compilations can cause the database cache and the distributed cache to have different digests and that causes the JavaScript to fail to load (and if the theme heavily customizes the site, it gives the impression that the site is broken) until the cache is cleared. This can happen in busy sites when 2 concurrent requests recompile the JavaScript files of a theme at the same time (this can happen when deploying a new Discourse version) and request A updates the database cache after request B did, and request B updates the distributed cache after request A did. Internal ticket: t60783. Co-authored-by: David Taylor <david@taylorhq.com>

dmorlock · May 5, 2022, 7:32pm

We are using V2.8.0. Which version contains the mentioned fix?

david · May 6, 2022, 9:51am

This fix is only in 2.9.0 (beta). I’ll see whether we can get it backported to stable since it’s a relatively simple fix: (PR here)

Edit: that’s merged into the stable branch @dmorlock. So if you run an upgrade (via the console, or via /admin/upgrade, the issue should be resolved.

dmorlock · May 6, 2022, 9:38pm

We just updated to the stable branch and are currently testing whether this fixed our issue.

david · June 5, 2022, 9:38pm

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.

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Missing theme-javascripts assets (http 404) on 2.8 stable

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