Metrics Analysis

Metrics Analysis

Authentication

IMPORTANT: Credentials are injected automatically by a proxy layer. Do NOT check for GRAFANA_API_KEY or PROMETHEUS_URL in environment variables - they won't be visible to you. Just run the scripts directly; authentication is handled transparently.

Core Principle: USE & RED Methods

USE Method (for infrastructure):

• Utilization - How busy is the resource?
• Saturation - How much work is queued?
• Errors - Are there error events?

RED Method (for services):

• Rate - Requests per second
• Errors - Error rate
• Duration - Latency distribution

Available Scripts

All scripts are in .claude/skills/metrics-analysis/scripts/

query_prometheus.py - Execute PromQL Queries

python .claude/skills/metrics-analysis/scripts/query_prometheus.py --query PROMQL [--time-range MINUTES] [--step STEP]

# Examples:
python .claude/skills/metrics-analysis/scripts/query_prometheus.py --query "up"
python .claude/skills/metrics-analysis/scripts/query_prometheus.py --query "rate(http_requests_total[5m])" --time-range 60
python .claude/skills/metrics-analysis/scripts/query_prometheus.py --query "histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))"

list_dashboards.py - Find Grafana Dashboards

python .claude/skills/metrics-analysis/scripts/list_dashboards.py [--query SEARCH_TERM]

# Examples:
python .claude/skills/metrics-analysis/scripts/list_dashboards.py
python .claude/skills/metrics-analysis/scripts/list_dashboards.py --query "api"

get_alerts.py - Check Firing Alerts

python .claude/skills/metrics-analysis/scripts/get_alerts.py [--state STATE]

# Examples:
python .claude/skills/metrics-analysis/scripts/get_alerts.py
python .claude/skills/metrics-analysis/scripts/get_alerts.py --state alerting

PromQL Quick Reference

Basic Queries

# Instant vector - current value
http_requests_total{service="api"}

# Range vector - values over time (for rate calculations)
http_requests_total{service="api"}[5m]

# Rate of increase per second
rate(http_requests_total{service="api"}[5m])

Common Operators

# Rate (counter → gauge, per second)
rate(http_requests_total[5m])

# Increase (total increase over time range)
increase(http_requests_total[1h])

# Average over time
avg_over_time(cpu_usage[5m])

# Histogram quantile (p95, p99)
histogram_quantile(0.95, rate(http_request_duration_bucket[5m]))

Aggregations

# Sum across all instances
sum(rate(http_requests_total[5m]))

# Group by label
sum by (service) (rate(http_requests_total[5m]))

# Average by label
avg by (instance) (cpu_usage)

# Top 5 by value
topk(5, sum by (service) (rate(http_requests_total[5m])))

Label Matching

# Exact match
http_requests_total{status="500"}

# Regex match
http_requests_total{status=~"5.."}

# Not equal
http_requests_total{status!="200"}

# Multiple labels
http_requests_total{service="api", status=~"5.."}

Investigation Workflows

1. Latency Investigation

# Step 1: Check overall latency trend
python query_prometheus.py --query 'histogram_quantile(0.95, rate(http_request_duration_seconds_bucket{service="api"}[5m]))' --time-range 60

# Step 2: Compare p50 vs p99
python query_prometheus.py --query 'histogram_quantile(0.50, rate(http_request_duration_seconds_bucket{service="api"}[5m]))'

# Step 3: Break down by endpoint
python query_prometheus.py --query 'histogram_quantile(0.95, sum by (endpoint) (rate(http_request_duration_seconds_bucket{service="api"}[5m])))'

2. Error Rate Investigation

# Step 1: Overall error rate
python query_prometheus.py --query 'sum(rate(http_requests_total{status=~"5.."}[5m])) / sum(rate(http_requests_total[5m]))'

# Step 2: Errors by status code
python query_prometheus.py --query 'sum by (status) (rate(http_requests_total{status=~"[45].."}[5m]))'

# Step 3: Errors by service
python query_prometheus.py --query 'sum by (service) (rate(http_requests_total{status=~"5.."}[5m]))'

3. Resource Investigation (CPU/Memory)

# CPU usage
python query_prometheus.py --query 'avg by (instance) (rate(container_cpu_usage_seconds_total{pod=~"api-.*"}[5m]))'

# Memory usage percentage
python query_prometheus.py --query 'container_memory_usage_bytes{pod=~"api-.*"} / container_spec_memory_limit_bytes{pod=~"api-.*"}'

Quick Commands Reference

Common Metric Patterns

Request Metrics

http_requests_total                    # Counter
http_request_duration_seconds_bucket   # Histogram
http_requests_in_flight               # Gauge

Kubernetes Metrics

container_cpu_usage_seconds_total
container_memory_usage_bytes
kube_pod_container_status_restarts_total
kube_pod_status_phase

Anti-Patterns to Avoid

1. ❌ Using rate() without range vector - Always include [5m] or similar
2. ❌ Comparing counters directly - Use rate() or increase() first
3. ❌ Wrong quantile math - histogram_quantile requires _bucket metrics
4. ❌ Missing label filters - Queries without filters return all series
5. ❌ Too-short time ranges - Use at least 2x your scrape interval for rate()