New Notification: Slow Response Time w/ Resend Interval

[stephenpapierski]

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Description

This new feature allows notifications to be configured surrounding the response time of a given service.

Resolves #1813
Closes #1878
Fixes #4035

• Add Resend Interval
• Add Last Response Time Calculation Method
• Add Threshold Calculation with Static Threshold and Relative to Avg. Response Methods
• Also send notification when service returns to normal response time
• Add threshold line to ping chart
• Add Slow badge to monitor dashboard when service is responding slow (no badge when Nominal)
• Add Slow/Nominal Entries to events log
• Add Slow/Nominal toast messages
• Add number of Slow services to Dashboard Quick Stats
• Update discord and slack notification providers to provide Slow/Nominal notifications that looks similar to the existing Up/Down notifications. By default, the rest of the notification providers fall back to plain text notifications.

Notification Control

Control	Behavior
Slow Response Notification	Enable slow response notifications
Resend Notification if Slow Response X times consecutively	Resend notification every x times the service responds slowly. A setting of 0 make it so that notifications are only sent when a service starts responding slowly or returns to a normal response time (situations 1 and 2 below)

Notifications are sent during 3 events.

1. Response time is greater than specified threshold (Service started responding slowly)
2. Response time returns to less than specified threshold (Service returned to normal response time)
3. Response time remains slow x consecutive times, if Resend Notification is greater than 0 (Service still responding slowly)

Response Time Calculation

There are multiple options for calculating the response time.

Method	Additional Parameters	Description
Average	Window Duration	Average response time during Window Duration
Max	Window Duration	Maximum response time during Window Duration
Last	N/A	Response time of the last heartbeat

Threshold Calculation

There are also multiple options for calculating the threshold.

Method	Additional Parameters	Description
Static Threshold	Threshold	Define a static threshold in milliseconds
Relative to Avg. Response	Threshold Multiplier	Calculate the threshold (Threshold Multiplier * 24-hour average response time). The goal here is that you don't have to tune your thresholds, it will simply tell you if your service is responding slower than "normal".

Type of change

Please delete any options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• User interface (UI)
• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the style guidelines of this project
• I ran ESLint and other linters for modified files
• I have performed a self-review of my own code and tested it
• I have commented my code, particularly in hard-to-understand areas
  (including JSDoc for methods)
• My changes generate no new warnings
• My code needed automated testing. I have added them (this is optional task)

Screenshots (if any)

Feature Disabled (default)

"Slow Response Notification" checkbox below rest of "General" fields.

Feature Enabled (with default settings)

Response Time Calculation

Average

Max

Last (Window Duration Hidden)

Threshold Calculation

Relative to Avg. Response

Static Threshold

Resend Interval

Dashboard Changes

• Add threshold line to ping chart

• Add Slow badge to monitor dashboard when service is responding slow (no badge when Nominal)

• Add Slow/Nominal entries to events log
  

• Add Slow/Nominal toast messages
  

• Add number of Slow services to Dashboard Quick Stats

Notification Providers

Discord

Slack