[regression] symlinked apps and CSS - ResourceLocator can not find a web root

[Daryes]

Seems to be the same problem as #5057 and others simlar.
Given the logs, it seems this was fixed in 12.x, but a change somewhere later removed the fix partially. I can go back to at least v13.0.1.1, up to 15.0.2.0

Currently, the apps work fine, while stored in a different dir symlinked back to the nextcloud main directory. But each time a user access them in the UI, an entry is generated in the log with an access error to a css file.

Steps to reproduce

1. store the non built-in application in another directory, which is a symlink

• nexcloud is under /server/websites/nextcloud/nextcloud-<version>/
• external app are under /server/websites/nextcloud/conf/apps2/
• create a symlink for nextcloud current version :
  ln -s /server/websites/nextcloud/nextcloud-<version> /server/websites/nextcloud/nextcloud
• create the apps symlink :
  ln -s /server/websites/nextcloud/conf/apps2 /server/websites/nextcloud/nextcloud/apps2

2. change the config.php with the app2 path information :

  'apps_paths' =>
  array (
    0 =>
    array (
      'path' => '/server/websites/nextcloud/nextcloud/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 =>
    array (
      'path' => '/server/websites/nextcloud/nextcloud/apps2',
      'url' => '/apps2',
      'writable' => true,
    ),
  ),

3. use nextcloud, add some apps (like calendar, contacts, ...)
4. click on the app bar at the top to show each of them, no need to do more. You can also see they appear correctly, and in fact they work correctly.
5. check the log. Multiply the number of line by the number of external apps, and the number of users.

Expected behaviour

no warning in the logs

Actual behaviour

these entries in the log, one for each application under a symlink in the path, each time a user selects the application panel in his browser. Given the filename, I suppose this is automatically generated, as nothing like this exists physically.

ResourceLocator can not find a web root (root: /server/websites/nextcloud/conf/apps2/contacts, file: index.php/css/contacts/3d4b-bdca-contacts.css?v=96f9b18ad190af3746726337d98b2100, webRoot: , throw: true)

ResourceLocator can not find a web root (root: /server/websites/nextcloud/conf/apps2/calendar, file: index.php/css/calendar/029b-bdca-app.min.css?v=96f9b18ad190af3746726337d98b2100, webRoot: , throw: true)

ResourceLocator can not find a web root (root: /server/websites/nextcloud/conf/apps2/notes, file: index.php/css/notes/21f4-bdca-notes.css?v=96f9b18ad190af3746726337d98b2100, webRoot: , throw: true)

(... continue for any application under the apps2 directory)

Server configuration

Operating system: Ubuntu 18.04
Web server: Apache 2.4
Database: Mariadb 10.3
PHP version: PHP 7.2.14

Nextcloud version: 15.0.2.0

Updated from an older Nextcloud/ownCloud or fresh install: upgraded from 14.0.4
Where did you install Nextcloud from: : tar.gz from nextcloud.com

[kesselb]

Ref #10437

[nebulade]

This also happens with the Cloudron app package with Nextcloud version 16.0.0
On Cloudron the apps folder is also symlinked. The files itself are publicly reachable just fine, still the ResourceLocator shows them missing in the error log.

[the-sane]

Confirming that this remains an issue in the v16 release series. It affects the new text app (nextcloud/text#157)

I believe this is the same issue that's being discussed over on the snap here: nextcloud-snap/nextcloud-snap#902. @juliushaertl stated in nextcloud-snap/nextcloud-snap#902 (comment):

This is most likely an issue of

server/lib/private/Template/ResourceLocator.php

Line 128 in 0eebff1

protected function findWebRoot($root) {

that doesn't detect the webroot properly if the apps directory is in a different place.

[szaimen]

Please fix this issue finally! That issue is very annoying and now also affects the usability (especially when enabling the dark mode through accessibility settings. If doing so there are a lot of icons missing in many apps (also in nextcloud_files).

[szaimen]

I think these are also the same error:
nextcloud-snap/nextcloud-snap#402
nextcloud-snap/nextcloud-snap#625

[kesselb]

server/lib/private/Template/CSSResourceLocator.php

Line 82 in 17d5e47

$app_path = realpath($app_path);

Symlink is resolved to early. findWebRoot method tries to determinate the webroot from the path. Nextcloud is installed to /home/nextcloud and the apps are in /home/nextcloud-apps. /home/nextcloud/apps2 is a symlink to /home/nextcloud/apps2. Its possible to detect the webroot for /home/nextcloud/apps2 but not /home/nextcloud-apps.

This one is the faulty commit b0d2966

cc @kyrofa @juliushaertl

[kyrofa]

This one is the faulty commit b0d2966

I'm not sure that's accurate given that the commit you reference is very old (it's what fixed things back in v12). Behavior around it might have changed in order to cause this regression, though.

[kesselb]

I'm not sure that's accurate given

That's right! I'm sorry my statement was misleading.

Behavior around it might have changed in order to cause this regression

I think so. Could you check if it works for snap without realpath?

[georgehrke]

Summoning our experts here: @skjnldsv @juliushaertl :)

@skjnldsv suspects it's just a debug log accidentally logged as error.