On our production server, we have strict SLAs concerning when our site can be down. I've noticed that when I update Craft CMS 3 (using "./craft update all" on the server), the site will go down for anywhere from 1-30 seconds. Once the update is completed, everything returns to working. Has anyone seen this before? How can I update Craft without downtime?
I think the best solution would be to integrate a CI with "Zero downtime deployment".
You may have a look at this article: https://craftquest.io/articles/what-are-zero-downtime-atomic-deployments
Or have a look at this deploy plugin: https://github.com/elfacht/craft-deploy
Or just google for "zero downtime deployment".