Including images in pages causes failure, which causes upstream switch at proxy

[Twan Goosen]

Linda reports that after trying to save a post with a selected thumbnail image, she gets logged out. What seems to be happening is that the upload process makes the website primary instance unavailable to the proxy, which then switches to the secondary instance where the user does not have a session.

Snippet from raw report ​on Slack:

Am not getting the message anymore, now when I upload a picture I am being logged out like last week. I still have to ask Andre to take a look what is going on
But this morning uploading a picture worked just once
Then I received the maintenance message and now it logged me off. I think this is what happened the very first time this problem occured.
I have no problem uploading via -> create content->upload media
but in a blog or news item it doesn’t work
Only in [Create Blog Post ... Image: <Browse>]
So not in the text editor, that works fine.
browsing for an image doesn’t work ,not from my pc or from the library.

Dieter could report on 2019-04-24 09:56

[Twan Goosen]

Central proxy logs report warn: upstream server temporarily disabled while reading response header from upstream and error: no live upstreams while connecting to upstream at matching times (see ​Kibana).

[Twan Goosen]

Dieter reports Drupal log entrys:

https://www.clarin.eu/admin/reports/event/351055
DATE    Wednesday, 24 April, 2019 - 09:53
USER    Linda Stokman
LOCATION    https://www.clarin.eu/admin/workbench/files
REFERRER    https://www.clarin.eu/admin/workbench/files/mine
MESSAGE    Notice: Undefined index: uri in workbench_media_preprocess_views_view_table() (line 94 of /var/www/localhost/htdocs/sites/all/modules/contrib/workbench_media/workbench_media.module).

This looks similar to Drupal issue report ​https://www.drupal.org/project/workbench_media/issues/2033961

Also (possibly unrelated)

https://www.clarin.eu/admin/reports/event/351084 - DATE    Wednesday, 24 April, 2019 - 10:01
USER    root
LOCATION    https://www.clarin.eu/ckeditor/xss
REFERRER    https://www.clarin.eu/node/4961/edit?destination=admin/content
MESSAGE    Notice: Undefined index: prepare callback in ckeditor_filter_xss() (line 289 of /var/www/localhost/htdocs/sites/all/modules/contrib/ckeditor/includes/ckeditor.page.inc).

[André Moreira]

I updated the ckeditor module to the dev version which includes some later fixes. One of them seems to tackle this problem, or at least the log message reported by Dieter.

Reference ​https://www.drupal.org/project/ckeditor/issues/2790539

Let's run it like this for awhile and see if the problem disappears.