Admin announcement feature

[csengerszabo]

User story

As a KKP admin I want to be able to send out announcements to other KKP users within the UI In order to inform them about important public informations like maintenance.

Solution details

• New tab in the UI of the admin panel where text-based announcements can be created and fired
• When an announcement is being fired, it means that it goes live and all KKP users can see it
• A message only disappears for the users when it explicitly was revoked by the admins from the admin panel
• Notifications panel can be potentially used for this
• When you click on one item in the notifications panel, a popup shows the whole message, which can be closed

REF https://github.com/kubermatic/dashboard/issues/6818

[csengerszabo]

/label sig/api

[judge-red]

I'd like to provide some input / wishes for this feature:

• A notification isn't good enough, notifications get ignored anyway (because they're hard to notice but most are also just not interesting enough to care). GitLab calls this broadcast messages. The idea is more that of a motd in Linux - you see it every time you log in, no need to read your ~/mbox to see it. Contrary to the motd, it shouldn't just be visible after log in but on all pages in the UI (until dismissed, if you choose to make them dismissible).
• imho it should be a banner across the whole page, but not covering anything of the UI - add a bar above or below the top navigation when there is a message. I guess it should have a height limit but be expandable upon clicking "more" or something like that.
• Cool would be if we could define either some kind of level (info, warn, error or such) or choose a theme (I suggest at least a couple, with blue, green, yellow, red and purple backgrounds) - so that there's a visual distinction between a "FYI there will be a maintenance window" (probably blue or maybe green) and a "READ THIS OR LOSE ALL DATA" (red) but also something neutral (probably purple or maybe blue)
• Ideally it supports markdown or similar syntax, and emoji. So we can make things bold/etc. and add some warning or party emotes, depending on the occasion. Definitely needs to allow for line breaking and links would be nice as well.
• It would be really cool if several notifications can be added/shown, maybe today we share the info about a maintenance window that is coming up in 2 weeks (and thus it stays up 2+ weeks), and tomorrow we share a warning about a regression (that is fixed in 2 days so we remove it again). Although if we can do multiline and have some format options, this isn't really required. Except I guess each notification could have its own level/color but if there's a neutral theme and emoji, that's okay.

Since I already mentioned this, my inspiration for requesting such a feature a while ago was GitLab (of which I'm just a user) - our GitLab admin team always shares important information (mostly about maintenance windows) like this and they're the only announcements I really see and read across all the tools I use daily 😅 See: https://docs.gitlab.com/ee/administration/broadcast_messages.html

[csengerszabo]

/assign @ahmadhamzh