Help - SLO Unit Test Helper

This tool helps you visualize SLO (Service Level Objective) scenarios by defining series of good and bad events over time.

Input Fields:

• Good/Bad Events: Define event series using a prometheus alert format.
  • A good/bad serie is defined by a series of segments.
  • A segment is defined by [initial]+[increment]x[steps].
    • initial: The starting value for this segment. Use # to use the last value from the previous segment.
    • increment: The value to add at each step within this segment.
    • steps: The number of data points in this segment.
  • The character # has special meaning in this tool:
    • Computes the initial value for the next segment from the last value of the previous segment.
    • This is not a valid value in Prometheus.
    • You get the real expression for Prometheus after the input box
    • It is used to continue the series from the last value of the previous segment.
  • Example: 0+0x10 10+1x10 #+3x10
    • starts at 0, and repeats 0 for 10 steps
    • then jumps to 10 and increments by 1 for another 10 steps
    • by using # we use the last value from the previous segment (20) as the initial value for the next segment
    • then continues from the last value with 3 increment for 10 steps
• Threshold 1 & 2: These are the threshold values for alert1 and alert2 series respectively.
  • For Proportion Rate over N: Thresholds are typically small numbers (e.g., 0.01 for 1%).
  • For Count over N: Thresholds represent a sum of bad events (e.g., 100).
    • This means that only the bad events is useful for the alerting.
• Alert1 Range (short): The window size (number of data points) used to calculate the alert1 series.
• Alert2 Range (long): The window size for the alert2 series.

Controls:

• Highlight Alert Checkbox:
  • Toggles the visual highlighting on the chart (red area)
  • Highlighting occurs when both of the following conditions are true:
    • alert1 is above threshold1
    • alert2 is above threshold2
• Debounce Alert Checkbox:
  • Enables alert debouncing.
  • If checked, highlights will only appear if:
    • The alert condition (alert1 > threshold1 AND alert2 > threshold2)
    • persists for the specified "Debounce Time".
• Debounce Time (steps):
  • The number of consecutive data points an alert condition must be true before it's visually highlighted.
  • Only applies if "Debounce alert" is checked.
• Show Time Format Checkbox: Toggles between showing step numbers and time format (e.g., "1h 30m") on the chart axis and tooltips. Time format uses the configured interval setting.
• Interval: Specifies the time between samples. Supports seconds (s), minutes (m), hours (h), and days (d). Examples: "1m" (1 minute), "5m" (5 minutes), "1h" (1 hour), "30s" (30 seconds). Default is "1m".
• Formula Selector: Choose the calculation method for alert1 and alert2 series:
  • Proportion Rate over N: Calculates sum(bad events in window) / (sum(bad events in window) + sum(good events in window)). This is a ratio, typically between 0 and 1.
  • Count over N: Calculates sum(bad events in window). This is an absolute count/sum of bad events over the specified window. It only uses the 'bad events' series for its calculation.

Chart Features:

• Series Display: The chart shows multiple series including alert1, alert2, thresholds, raw bad/good events (hidden by default), and their rates (hidden by default). You can toggle series visibility in the chart legend.
• Zoom and Pan: The chart supports zooming and panning for detailed analysis. Use mouse wheel to zoom and drag to pan.
• Tooltips: Hover over data points to see detailed values. Tooltips show step number or time format based on the "Show Time Format" setting.
• Auto-update: The chart automatically updates when you modify any input values. Changes to bad/good events are throttled to prevent excessive updates.

Advanced Series Syntax:

• Special Values: Use _ for special values that don't affect calculations (e.g., _x5 for 5 special values).
• Decimal Values: Support for decimal numbers in series definitions (e.g., 0.5+0.1x2).
• Negative Values: Support for negative initial values and decrements (e.g., -2+4x3 or 1-2x4).
• Shorthand Notation: Use axn as shorthand for a+0xn (constant value for n+1 steps).

Data Persistence:

All your configuration settings are automatically saved to your browser's localStorage, so they will persist between sessions.

Testing:

Add ?test=true to the URL to run unit tests in the browser console, which verify the core functionality of the series parsing and calculation functions.