Thresholds

Thresholds define the boundaries for metric status calculation, enabling traffic-light style health indicators.

Threshold Structure

{
  "thresholds": {
    "green": 99.95,
    "yellow": 99.9,
    "red": 99.0
  }
}

Fields

Field	Type	Description
green	number	Threshold for "healthy" status
yellow	number	Threshold for "warning" status
red	number	Threshold for "critical" status

Status Calculation

Status is calculated based on the metric's trend direction.

Higher Better (e.g., Availability)

For metrics where higher values are better:

Current Value	Status
>= green	Green
>= yellow	Yellow
< yellow	Red

Example:

{
  "current": 99.92,
  "trendDirection": "higher_better",
  "thresholds": {
    "green": 99.95,
    "yellow": 99.9,
    "red": 99.0
  }
}
// Status: Yellow (99.92 >= 99.9 but < 99.95)

Lower Better (e.g., Latency)

For metrics where lower values are better:

Current Value	Status
<= green	Green
<= yellow	Yellow
> yellow	Red

Example:

{
  "current": 180,
  "trendDirection": "lower_better",
  "thresholds": {
    "green": 100,
    "yellow": 200,
    "red": 500
  }
}
// Status: Yellow (180 <= 200 but > 100)

Programmatic Status Calculation

Use CalculateStatus() to compute status in code:

metric := prism.Metric{
    Current:        99.92,
    TrendDirection: prism.TrendHigherBetter,
    Thresholds: &prism.Thresholds{
        Green:  99.95,
        Yellow: 99.9,
        Red:    99.0,
    },
}

status := metric.CalculateStatus()
fmt.Println(status) // "Yellow"

Status Values

Status	Constant	Color	Meaning
Green	green	🟢	Healthy, meeting targets
Yellow	yellow	🟡	Warning, needs attention
Red	red	🔴	Critical, requires action

Examples by Metric Type

Availability (Higher Better)

{
  "id": "ops-availability",
  "name": "Service Availability",
  "metricType": "rate",
  "trendDirection": "higher_better",
  "unit": "%",
  "current": 99.95,
  "thresholds": {
    "green": 99.95,
    "yellow": 99.9,
    "red": 99.0
  }
}

Latency (Lower Better)

{
  "id": "ops-p99-latency",
  "name": "P99 Latency",
  "metricType": "latency",
  "trendDirection": "lower_better",
  "unit": "ms",
  "current": 250,
  "thresholds": {
    "green": 200,
    "yellow": 500,
    "red": 1000
  }
}

Error Rate (Lower Better)

{
  "id": "ops-error-rate",
  "name": "Error Rate",
  "metricType": "rate",
  "trendDirection": "lower_better",
  "unit": "%",
  "current": 0.15,
  "thresholds": {
    "green": 0.1,
    "yellow": 0.5,
    "red": 1.0
  }
}

MTTR (Lower Better)

{
  "id": "ops-mttr",
  "name": "Mean Time to Recovery",
  "metricType": "latency",
  "trendDirection": "lower_better",
  "unit": "hours",
  "current": 2,
  "thresholds": {
    "green": 1,
    "yellow": 4,
    "red": 24
  }
}

Threshold vs. Target vs. SLO

Concept	Purpose	Use Case
Target	Aspirational goal	Planning, roadmaps
SLO	Contractual commitment	SLA compliance
Thresholds	Status visualization	Dashboards, alerts

These can be different:

{
  "current": 99.95,
  "target": 99.99,
  "slo": {
    "target": ">=99.9%",
    "operator": "gte",
    "value": 99.9
  },
  "thresholds": {
    "green": 99.95,
    "yellow": 99.9,
    "red": 99.0
  }
}

In this example:

• Target: 99.99% (aspirational)
• SLO: 99.9% (minimum commitment)
• Green threshold: 99.95% (above SLO, approaching target)