williamzujkowski/Service Level Objective Validator

Purpose & When-To-Use

Trigger conditions:

• Existing SLO definition needs validation against actual service performance
• SRE team requires automated alerting on error budget consumption
• Compliance audit demands proof of SLO adherence over time period
• Incident postmortem reveals SLO was breached but no alerts fired
• Service migration requires SLO re-validation with new infrastructure
• Multi-window burn rate alerts needed (fast/slow burn detection)
• Dashboard generation needed for executive SLO reporting

Use this skill when you have an existing SLO definition and need to validate it against real metrics, generate appropriate alerting rules with burn rate thresholds, and create compliance reports or monitoring dashboards.

Pre-Checks

Before execution, verify:

1. Time normalization: NOW_ET = 2025-10-26T03:51:54-04:00 (NIST/time.gov semantics, America/New_York)
2. Input schema validation:

• slo_definition contains target, window, and sli_query fields
• metrics_source is one of: prometheus, cloudwatch, datadog, newrelic
• time_window is valid duration: 7d, 28d, or 90d (default: 28d)
• error_budget_policy is one of: strict, moderate, flexible (default: moderate)

1. Source freshness: All cited sources (Google SRE Workbook, Prometheus docs, Sloth) accessed on NOW_ET
2. Metrics availability: Target metrics platform is accessible and contains historical data for time_window

Abort conditions:

• SLO definition missing required fields (target, window, sli_query)
• Metrics source unavailable or lacks data for validation period
• SLI query syntax invalid for specified metrics platform
• Historical data gap >10% of validation window (insufficient for accurate validation)

Procedure

Tier 1 (Fast Path)

Token budget: T1 ≤2k tokens

Scope: Basic SLO validation for common availability/latency targets with simple alerting.

Steps:

1. Parse SLO definition:

• Extract target (e.g., 99.9%), window (e.g., 30d), sli_query (metrics query)
• Validate query syntax for metrics_source platform
• Calculate error budget: error_budget = (1 - target) * window
• Example: 99.9% over 30d = 43.2 minutes allowed downtime

1. Query metrics platform (accessed 2025-10-26T03:51:54-04:00: https://prometheus.io/docs/prometheus/latest/querying/basics/):

• Execute sli_query over time_window (default 28d)
• Calculate actual SLO achievement: actual_slo = avg(sli_results)
• Identify breach periods: timestamps where SLI < target

1. Compute error budget status:

• consumed_budget = (1 - actual_slo) * window
• remaining_budget = error_budget - consumed_budget
• compliance = (consumed_budget <= error_budget) ? "PASS" : "FAIL"

1. Generate basic alert rule (Prometheus example):

yaml

• alert: SLOBudgetExhausted

expr: (1 - sli_query) > (1 - 0.999) for: 5m labels: severity: critical annotations: summary: "Error budget exhausted"

1. Output: Validation report (pass/fail), current budget status, basic alert rule

Tier 2 (Extended Validation)

Token budget: T2 ≤6k tokens

Scope: Production SLO validation with multi-window burn rate alerts and compliance reporting.

Steps:

1. Multi-window SLO validation (accessed 2025-10-26T03:51:54-04:00: https://sre.google/workbook/implementing-slos/):

• Validate SLO over multiple time windows: 7d, 28d, 90d
• Calculate compliance for each window independently
• Identify short-term degradation (7d breach) vs long-term trends (90d)
• Generate breach timeline: all periods where SLI fell below target

1. Burn rate calculation (accessed 2025-10-26T03:51:54-04:00: https://sre.google/workbook/alerting-on-slos/):

• Fast burn (1-hour window): Detects rapid error budget consumption
• Threshold: 14.4x normal burn rate for 99.9% SLO
• Formula: (1 - sli_1h) > 14.4 * (1 - target)
• Medium burn (6-hour window): Detects moderate degradation
• Threshold: 6x normal burn rate
• Formula: (1 - sli_6h) > 6 * (1 - target)
• Slow burn (3-day window): Detects gradual degradation
• Threshold: 1x normal burn rate (budget exhaustion in 30 days)
• Formula: (1 - sli_3d) > 1 * (1 - target)

1. Error budget policy enforcement (based on error_budget_policy parameter):

• Strict: Alert when >75% budget consumed, freeze deploys at >90%
• Moderate: Alert when >85% budget consumed, freeze deploys at >95%
• Flexible: Alert when >90% budget consumed, no automatic freeze

1. Platform-specific alerting rules generation:

Prometheus (accessed 2025-10-26T03:51:54-04:00: https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/): yaml groups:

• name: slo_alerts

interval: 30s rules:

• alert: SLOFastBurn

expr: | (1 - (sum(rate(http_requests_total{status!~"5.."}1h])) / sum(rate(http_requests_total1h])))) > (14.4 (1 - 0.999)) for: 2m labels: severity: critical annotations: summary: "Fast burn: error budget will exhaust in 2 hours"

• alert: SLOSlowBurn

expr: | (1 - (sum(rate(http_requests_total{status!~"5.."}3d])) / sum(rate(http_requests_total3d])))) > (1 (1 - 0.999)) for: 15m labels: severity: warning annotations: summary: "Slow burn: error budget will exhaust in 30 days"

CloudWatch: json { "AlarmName": "SLO-FastBurn-API", "ComparisonOperator": "GreaterThanThreshold", "EvaluationPeriods": 2, "MetricName": "ErrorRate", "Namespace": "AWS/ApplicationELB", "Period": 3600, "Statistic": "Average", "Threshold": 0.0144, "ActionsEnabled": true, "AlarmActions": ["arn:aws:sns:us-east-1:123456789:critical-alerts"] }

1. Dashboard configuration (accessed 2025-10-26T03:51:54-04:00: https://github.com/slok/sloth):

• Panel 1: SLO compliance gauge (current achievement vs target)
• Panel 2: Error budget remaining (time-series graph)
• Panel 3: Burn rate by window (1h, 6h, 3d stacked graph)
• Panel 4: Breach timeline (heatmap showing SLO violations)
• Panel 5: Time to budget exhaustion (calculated metric)

Grafana example (using Sloth format): yaml version: "prometheus/v1" service: "api-service" slos:

• name: "availability"

objective: 99.9 sli: events: error_query: sum(rate(http_requests_total{status=~"5.."}{{.window}}])) total_query: sum(rate(http_requests_total{{.window}}])) alerting: name: "API SLO" page_alert: labels: severity: critical ticket_alert: labels: severity: warning

1. Compliance audit report:

• Summary: Overall SLO compliance (PASS/FAIL) for each time window
• Breach details: Start/end timestamps, duration, root cause (if known)
• Budget consumption: Total consumed, remaining, projected exhaustion date
• Alerting effectiveness: Were alerts fired during breach periods?
• Recommendations: SLO adjustment suggestions based on historical performance

1. Comprehensive output:

• Multi-window validation report with breach timeline
• Platform-specific alerting rules (Prometheus/CloudWatch/Datadog)
• Error budget status with burn rate metrics
• Dashboard configuration (Grafana/CloudWatch JSON)
• Compliance audit report

Sources cited (accessed 2025-10-26T03:51:54-04:00):

• Google SRE Workbook - Implementing SLOs: https://sre.google/workbook/implementing-slos/
• Google SRE Workbook - Alerting on SLOs: https://sre.google/workbook/alerting-on-slos/
• Prometheus Alerting Rules: https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/
• Sloth SLO Generator: https://github.com/slok/sloth

Tier 3 (Deep Analysis)

Token budget: T3 ≤12k tokens

Scope: Advanced SLO validation with anomaly detection, trend analysis, and automated remediation recommendations.

Steps:

1. Historical trend analysis:

• Analyze SLO performance over extended period (90d, 180d, 1y)
• Identify seasonality patterns (weekday/weekend, business hours, holidays)
• Calculate baseline SLO achievement by time period
• Detect anomalous degradation periods (statistical outliers)

1. SLO sensitivity analysis:

• Simulate impact of SLO target adjustments (e.g., 99.9% → 99.95%)
• Calculate required infrastructure improvements to meet tighter SLOs
• Estimate cost of achieving higher reliability (additional resources, redundancy)

1. Multi-service dependency analysis:

• Identify upstream/downstream service dependencies
• Calculate composite SLO (product of dependent service SLOs)
• Example: If Service A (99.9%) depends on Service B (99.95%), composite = 99.85%
• Recommend SLO targets for dependencies to achieve overall target

1. Automated remediation recommendations:

• Analyze breach root causes from incident reports/logs
• Generate prioritized backlog of reliability improvements
• Estimate error budget recovery timeline for each improvement
• Link to related runbooks/playbooks for common failure modes

1. Advanced alerting strategies:

• Adaptive thresholds: Adjust burn rate thresholds based on time-of-day/day-of-week patterns
• Multi-burn-rate windows: Combine multiple windows (e.g., 1h AND 6h) to reduce false positives
• Budget forecasting: Predict budget exhaustion based on current burn rate trends

1. Comprehensive SLO evaluation:

• Generate executive summary report with visualizations
• Provide SLO tuning recommendations (target too strict/loose?)
• Include cost/benefit analysis of SLO improvements
• Export results to common formats (PDF, Excel, JSON)

Decision Rules

SLO compliance determination:

• PASS: Actual SLO ≥ target for all evaluated time windows
• FAIL: Actual SLO < target for any evaluated time window
• WARNING: Within 5% of error budget exhaustion (trigger proactive review)

Burn rate alert severity mapping:

• Critical (page): Fast burn (1h) consuming >2% of 30-day budget
• Warning (ticket): Medium burn (6h) consuming >5% of 30-day budget
• Info (notification): Slow burn (3d) consuming >10% of 30-day budget

Dashboard generation strategy:

• Prometheus metrics: Use Grafana with Sloth-generated dashboards
• CloudWatch metrics: Use native CloudWatch dashboards
• Datadog metrics: Use Datadog SLO UI with custom widgets
• Multi-platform: Generate platform-agnostic JSON schema, manual import required

Ambiguity thresholds:

• If slo_definition lacks window → default to 30d (SRE standard)
• If error_budget_policy not specified → default to moderate
• If metrics have >10% data gaps → issue warning, proceed with available data
• If SLO target >99.99% → issue warning about feasibility

Abort/stop conditions:

• Metrics query returns zero results (invalid query or no data)
• SLO definition malformed (missing required fields)
• Metrics platform authentication/access fails
• Historical data coverage <50% of validation window

Output Contract

Required fields:

json
{
  "validation_report": {
    "slo_name": "string",
    "target": "number (e.g., 99.9)",
    "windows": [
      {
        "period": "string (7d, 28d, 90d)",
        "actual_slo": "number (achieved %)",
        "compliance": "PASS | FAIL | WARNING",
        "error_budget_total": "number (minutes)",
        "error_budget_consumed": "number (minutes)",
        "error_budget_remaining": "number (minutes)",
        "breach_count": "number",
        "breach_timeline": [
          {
            "start": "ISO8601 timestamp",
            "end": "ISO8601 timestamp",
            "duration_minutes": "number",
            "severity": "critical | warning"
          }
        ]
      }
    ],
    "overall_compliance": "PASS | FAIL"
  },
  "alerting_rules": {
    "platform": "string (prometheus | cloudwatch | datadog)",
    "format": "yaml | json",
    "rules": "string (platform-specific alert definitions)"
  },
  "error_budget_status": {
    "current_burn_rate_1h": "number (multiplier, e.g., 14.4x)",
    "current_burn_rate_6h": "number",
    "current_burn_rate_3d": "number",
    "time_to_exhaustion": "string (e.g., '2 hours' | '15 days' | 'N/A')",
    "budget_policy_triggered": "boolean",
    "recommended_action": "freeze_deploys | monitor_closely | continue_normal_operations"
  },
  "dashboard_config": {
    "platform": "string (grafana | cloudwatch | datadog)",
    "format": "json | yaml",
    "config": "object (platform-specific dashboard definition)"
  }
}

Optional fields:

• trend_analysis: Historical SLO performance trends (T3 only)
• remediation_recommendations: Prioritized reliability improvements (T3 only)
• compliance_audit: Detailed audit report with breach analysis

Validation:

• All time windows must have compliance status
• Burn rate calculations must use correct multipliers for target SLO
• Dashboard config must be valid JSON/YAML for target platform
• Alert rules must be syntactically correct for metrics platform

Examples

Input:

json
{
  "slo_definition": {
    "name": "API Availability",
    "target": 99.9,
    "window": "30d",
    "sli_query": "sum(rate(http_requests_total{status!~\"5..\"}[5m])) / sum(rate(http_requests_total[5m]))"
  },
  "metrics_source": "prometheus",
  "time_window": "28d",
  "error_budget_policy": "moderate"
}

Output (abbreviated):

json
{
  "validation_report": {
    "slo_name": "API Availability",
    "target": 99.9,
    "windows": [{
      "period": "28d",
      "actual_slo": 99.87,
      "compliance": "FAIL",
      "error_budget_consumed": 52.4,
      "error_budget_remaining": -12.2,
      "breach_count": 3
    }],
    "overall_compliance": "FAIL"
  },
  "error_budget_status": {
    "current_burn_rate_1h": 2.1,
    "time_to_exhaustion": "N/A (budget exhausted)"
  }
}

Quality Gates

Token budgets:

• T1: ≤2k tokens for basic SLO validation with simple alerting
• T2: ≤6k tokens for multi-window validation with burn rate alerts and dashboards
• T3: ≤12k tokens for trend analysis, remediation recommendations, and advanced reporting

Safety requirements:

• Validate metrics queries are read-only (no writes to metrics platform)
• Warn if SLO breach detected but no historical incidents recorded
• Ensure alert rules don't create excessive notification volume (>10 alerts/day = review needed)

Auditability:

• All validation results include query timestamps and data sources
• Breach timeline provides exact start/end times for compliance review
• Alert rules are version-controlled and reproducible

Determinism:

• Same SLO definition + metrics data produces identical validation report
• Burn rate calculations use standard formulas from Google SRE literature
• Error budget math is transparent and auditable

Resources

Primary sources:

• Google SRE Workbook - Implementing SLOs: https://sre.google/workbook/implementing-slos/
• Google SRE Workbook - Alerting on SLOs: https://sre.google/workbook/alerting-on-slos/
• Prometheus Alerting Rules: https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/
• Datadog SLO Monitoring: https://docs.datadoghq.com/monitors/service_level_objectives/

Reference implementations:

• Sloth (SLO generator): https://github.com/slok/sloth
• OpenSLO Specification: https://github.com/OpenSLO/OpenSLO
• Pyrra (SLO framework): https://github.com/pyrra-dev/pyrra

Additional reading:

• The Art of SLOs: https://www.alex-hidalgo.com/the-art-of-slos
• SLI/SLO Workshop: https://www.usenix.org/conference/srecon19americas/presentation/fong-jones