Fix: Unreachable Notifications

[peaklabs-dev]

Changes

• Fix: Unreachable notifications were sent even if the server was probably reachable and just had some minor temporary connection problems.
• fix: duplicated ServerCheckJob in dev
• Feat: New unreachable notification handling:
  • When a server becomes unreachable (is_reachable set to false), the first time is discarded and is_reachable is set back to true.
  • If the server is unreachable again 1min later (or 5min later for Cloud) set and checked via the ServerCheckJob, it will start 3 fast checks in 5s intervals (locally this will take 15s, remote servers will take about 15s each check so all 3 checks 45s).
  • If these 3 quick status checks also fail, we can be pretty sure that the server is probably offline and then we send out the unreachable notification.

Note

• I added an event because the first check when I set is_reachable back to true always triggered the second step (because of isDirty), which is not what we want.

Issues

• fix [Bug]: Multiple false "Your server is unreachable" mails through the day #4407

/claim #4407

[andrasbacsai]

Thank you for the PR!