monitoring-observability

name

monitoring-observability

description

Monitoring and observability strategy, implementation, and troubleshooting. Use this skill whenever the user mentions monitoring, observability, metrics, logs, traces, alerting, SLOs, Prometheus, Grafana, Datadog, Loki, or OpenTelemetry. Triggers include designing metrics strategy (Four Golden Signals, RED/USE), setting up Prometheus/Grafana/Loki, creating alerts or dashboards, calculating SLOs and error budgets, instrumenting with OpenTelemetry, analyzing performance issues, choosing between monitoring tools, optimizing Datadog costs, migrating to open-source stack, and setting up distributed tracing.

Monitoring & Observability

Core Workflow: Observability Implementation

Use this decision tree to determine your starting point:

Are you setting up monitoring from scratch?
├─ YES → Start with "1. Design Metrics Strategy"
└─ NO → Do you have an existing issue?
    ├─ YES → Go to "9. Troubleshooting & Analysis"
    └─ NO → Are you improving existing monitoring?
        ├─ Alerts → Go to "3. Alert Design"
        ├─ Dashboards → Go to "4. Dashboard & Visualization"
        ├─ SLOs → Go to "5. SLO & Error Budgets"
        ├─ Tool selection → Read references/tool_comparison.md
        └─ Using Datadog? High costs? → Go to "7. Datadog Cost Optimization & Migration"

---

1. Design Metrics Strategy

Start with The Four Golden Signals

Every service should monitor: Latency (p50/p95/p99), Traffic (req/s), Errors (failure rate), Saturation (resource utilization).

RED Method (request-driven): Rate, Errors, Duration | USE Method (infrastructure): Utilization, Saturation, Errors

Quick Start - Web Application Example:

# Rate (requests/sec)
sum(rate(http_requests_total[5m]))

# Errors (error rate %)
sum(rate(http_requests_total{status=~"5.."}[5m]))
  /
sum(rate(http_requests_total[5m])) * 100

# Duration (p95 latency)
histogram_quantile(0.95,
  sum(rate(http_request_duration_seconds_bucket[5m])) by (le)
)

Deep dive: references/metrics_design.md — metric types, cardinality, naming conventions, dashboard design

Querying Metrics Directly

Query Prometheus and CloudWatch metrics using CLI/curl:

# Query Prometheus instant value
curl -s 'http://localhost:9090/api/v1/query?query=rate(http_requests_total[5m])' | jq .

# Query Prometheus over a time range (last 1h, 15s step)
curl -s 'http://localhost:9090/api/v1/query_range?query=rate(http_requests_total[5m])&start='$(date -u -v-1H +%Y-%m-%dT%H:%M:%SZ)'&end='$(date -u +%Y-%m-%dT%H:%M:%SZ)'&step=15s' | jq .

# Query CloudWatch metrics (e.g., EC2 CPU over last 1 hour)
aws cloudwatch get-metric-statistics \
  --namespace AWS/EC2 \
  --metric-name CPUUtilization \
  --dimensions Name=InstanceId,Value=i-1234567890abcdef0 \
  --start-time $(date -u -v-1H +%Y-%m-%dT%H:%M:%SZ) \
  --end-time $(date -u +%Y-%m-%dT%H:%M:%SZ) \
  --period 300 \
  --statistics Average Maximum

---

2. Log Aggregation & Analysis

Structured Logging Checklist

Every log entry should include: timestamp (ISO 8601), log level, message, service name, request ID (for tracing).

Example structured log (JSON):

{
  "timestamp": "2024-10-28T14:32:15Z",
  "level": "error",
  "message": "Payment processing failed",
  "service": "payment-service",
  "request_id": "550e8400-e29b-41d4-a716-446655440000",
  "user_id": "user123",
  "order_id": "ORD-456",
  "error_type": "GatewayTimeout",
  "duration_ms": 5000
}

Log Analysis

Analyze logs for errors, patterns, and anomalies:

# Analyze log file for patterns
python3 scripts/log_analyzer.py application.log

# Show error lines with context
python3 scripts/log_analyzer.py application.log --show-errors

# Extract stack traces
python3 scripts/log_analyzer.py application.log --show-traces

→ Script: scripts/log_analyzer.py

Deep dive: references/logging_guide.md — structured logging, aggregation patterns (ELK, Loki, CloudWatch), PII redaction, sampling

---

3. Alert Design

Alert Design Principles

1. Actionable - If you can't act on it, don't alert
2. Symptom-based - Alert on user experience, not components
3. SLO-tied - Connect to business impact
4. Low noise - Only page for critical issues

Alert Severity Levels

Severity	Response Time	Example
Critical	Page immediately	Service down, SLO violation
Warning	Ticket, review in hours	Elevated error rate, resource warning
Info	Log for awareness	Deployment completed, scaling event

Multi-Window Burn Rate Alerting

Alert when error budget is consumed too quickly:

# Fast burn (1h window) - Critical
- alert: ErrorBudgetFastBurn
  expr: |
    (error_rate / 0.001) > 14.4  # 99.9% SLO
  for: 2m
  labels:
    severity: critical

# Slow burn (6h window) - Warning
- alert: ErrorBudgetSlowBurn
  expr: |
    (error_rate / 0.001) > 6  # 99.9% SLO
  for: 30m
  labels:
    severity: warning

Alert Quality Checker

Audit your alert rules against best practices:

# Check single file
python3 scripts/alert_quality_checker.py alerts.yml

# Check all rules in directory
python3 scripts/alert_quality_checker.py /path/to/prometheus/rules/

Checks: naming conventions, required labels/annotations, PromQL quality, 'for' clause to prevent flapping.

→ Script: scripts/alert_quality_checker.py

Alert Templates

Production-ready alert rule templates:

→ Templates:

• assets/templates/prometheus-alerts/webapp-alerts.yml - Web application alerts
• assets/templates/prometheus-alerts/kubernetes-alerts.yml - Kubernetes alerts

Deep dive: references/alerting_best_practices.md — alert design patterns, routing, inhibition rules, runbook structure, on-call practices

Runbook Template

Create comprehensive runbooks for your alerts:

→ Template: assets/templates/runbooks/incident-runbook-template.md

---

4. Dashboard & Visualization

Dashboard Design Principles

1. Top-down layout: Most important metrics first
2. Color coding: Red (critical), yellow (warning), green (healthy)
3. Consistent time windows: All panels use same time range
4. Limit panels: 8-12 panels per dashboard maximum
5. Include context: Show related metrics together

Recommended layout: Overall Health (single stats) -> Request Rate & Errors -> Latency Distribution -> Resource Usage

Generate Grafana Dashboards

Automatically generate dashboards from templates:

# Web application dashboard
python3 scripts/dashboard_generator.py webapp \
  --title "My API Dashboard" \
  --service my_api \
  --output dashboard.json

# Kubernetes dashboard
python3 scripts/dashboard_generator.py kubernetes \
  --title "K8s Production" \
  --namespace production \
  --output k8s-dashboard.json

# Database dashboard
python3 scripts/dashboard_generator.py database \
  --title "PostgreSQL" \
  --db-type postgres \
  --instance db.example.com:5432 \
  --output db-dashboard.json

Supports: Web applications, Kubernetes, Databases (PostgreSQL, MySQL).

→ Script: scripts/dashboard_generator.py

---

5. SLO & Error Budgets

SLO Fundamentals

SLI (measurement), SLO (target), Error Budget (allowed failure = 100% - SLO). See references/slo_sla_guide.md for full definitions.

Common SLO Targets

Availability	Downtime/Month	Use Case
99%	7.2 hours	Internal tools
99.9%	43.2 minutes	Standard production
99.95%	21.6 minutes	Critical services
99.99%	4.3 minutes	High availability

SLO Calculator

Calculate compliance, error budgets, and burn rates:

# Show SLO reference table
python3 scripts/slo_calculator.py --table

# Calculate availability SLO
python3 scripts/slo_calculator.py availability \
  --slo 99.9 \
  --total-requests 1000000 \
  --failed-requests 1500 \
  --period-days 30

# Calculate burn rate
python3 scripts/slo_calculator.py burn-rate \
  --slo 99.9 \
  --errors 50 \
  --requests 10000 \
  --window-hours 1

→ Script: scripts/slo_calculator.py

Deep dive: references/slo_sla_guide.md — choosing SLIs, setting targets, error budget policies, burn rate alerting, SLA contracts

---

6. Distributed Tracing

When to Use Tracing

Use distributed tracing when you need to:

• Debug performance issues across services
• Understand request flow through microservices
• Identify bottlenecks in distributed systems
• Find N+1 query problems

OpenTelemetry Implementation

Python example:

from opentelemetry import trace

tracer = trace.get_tracer(__name__)

@tracer.start_as_current_span("process_order")
def process_order(order_id):
    span = trace.get_current_span()
    span.set_attribute("order.id", order_id)

    try:
        result = payment_service.charge(order_id)
        span.set_attribute("payment.status", "success")
        return result
    except Exception as e:
        span.set_status(trace.Status(trace.StatusCode.ERROR))
        span.record_exception(e)
        raise

Sampling Strategies

• Development: 100% (ALWAYS_ON)
• Staging: 50-100%
• Production: 1-10% (or error-based sampling)

Error-based sampling (always sample errors, 1% of successes):

class ErrorSampler(Sampler):
    def should_sample(self, parent_context, trace_id, name, **kwargs):
        attributes = kwargs.get('attributes', {})

        if attributes.get('error', False):
            return Decision.RECORD_AND_SAMPLE

        if trace_id & 0xFF < 3:  # ~1%
            return Decision.RECORD_AND_SAMPLE

        return Decision.DROP

OTel Collector Configuration

→ Template: assets/templates/otel-config/collector-config.yaml — OTLP/Prometheus/host metrics receivers, batching, tail sampling, multiple exporters (Tempo, Jaeger, Loki, Prometheus, CloudWatch, Datadog)

Deep dive: references/tracing_guide.md — OTel instrumentation (Python, Node.js, Go, Java), context propagation, backend comparison, analysis patterns

---

7. Datadog Cost Optimization & Migration

Scenario 1: I'm Using Datadog and Costs Are Too High

Check usage directly in the Datadog UI at Plan & Usage > Usage Summary, or query the API:

# Get Datadog usage summary for the current month (requires DD_API_KEY and DD_APP_KEY)
curl -s -X GET "https://api.datadoghq.com/api/v1/usage/summary?start_month=$(date -u +%Y-%m)" \
  -H "DD-API-KEY: ${DD_API_KEY}" \
  -H "DD-APPLICATION-KEY: ${DD_APP_KEY}" | jq .

# Get hourly usage for hosts (identify peak usage)
curl -s -X GET "https://api.datadoghq.com/api/v1/usage/hosts?start_hr=$(date -u -v-24H +%Y-%m-%dT%H)" \
  -H "DD-API-KEY: ${DD_API_KEY}" \
  -H "DD-APPLICATION-KEY: ${DD_APP_KEY}" | jq .

Common Cost Optimization Strategies

• Custom Metrics (20-40% savings): Remove high-cardinality tags, delete unused metrics, aggregate before sending
• Log Management (30-50% savings): Sample high-volume services, exclude debug logs in prod, archive to S3 after 7 days
• APM (15-25% savings): Reduce trace sampling (10% to 5%), remove APM from non-critical services
• Infrastructure (10-20% savings): Use container-based pricing, remove agents from ephemeral instances, consolidate staging

Scenario 2: Migrating Away from Datadog

Migration to open-source stack (Prometheus + Grafana, Loki, Tempo/Jaeger, Alertmanager). Estimated savings: 60-77%.

Migration Strategy

• Phase 1 (Month 1-2): Deploy open-source stack in parallel, migrate metrics first, validate accuracy
• Phase 2 (Month 2-3): Convert dashboards to Grafana, translate alert rules (DQL to PromQL), train team
• Phase 3 (Month 3-4): Set up Loki for logs, deploy Tempo/Jaeger for traces, update instrumentation
• Phase 4 (Month 4-5): Confirm all functionality migrated, decommission Datadog

Full migration guide: references/datadog_migration.md | Query translation: references/dql_promql_translation.md

---

8. Tool Selection & Comparison

Solution	Monthly Cost (100 hosts)	Best For
Prometheus + Loki + Tempo	$1,500	Kubernetes, budget-conscious, ops-capable teams
Grafana Cloud	$3,000	Open-source stack, low ops overhead
Datadog	$8,000	Ease of use, full observability out of the box
ELK Stack	$4,000	Heavy log analysis, powerful search
CloudWatch	$2,000	Single AWS provider, simple needs

Deep dive: references/tool_comparison.md — full comparison of metrics, logging, tracing, and full-stack platforms

---

9. Troubleshooting & Analysis

Health Check Validation

Validate health check endpoints using curl:

# Check endpoint returns 200 and measure response time
curl -sf -o /dev/null -w "status:%{http_code} time:%{time_total}s\n" https://api.example.com/health

# Get full response body (check for JSON 'status' field, version info)
curl -sf https://api.example.com/health | jq .

# Check multiple endpoints in sequence
for ep in /health /readiness /liveness; do
  printf "%-20s " "$ep"
  curl -sf -o /dev/null -w "status:%{http_code} time:%{time_total}s\n" "https://api.example.com${ep}"
done

What to verify: 200 status, response time < 1s, JSON format with status field, version/build info, dependency checks, no caching headers (Cache-Control: no-cache).

Common Troubleshooting Workflows

High Latency: Check dashboards for spike -> query traces for slow ops -> check DB slow queries -> check external APIs -> review deployments -> check resource utilization

High Error Rate: Check error logs -> identify affected endpoints -> check dependency health -> review deployments -> check resource limits -> verify configuration

Service Down: Check pods/instances running -> check health endpoint -> review deployments -> check resource availability -> check network -> review startup logs

---

Quick Reference Commands

Prometheus Queries

# Request rate
sum(rate(http_requests_total[5m]))

# Error rate
sum(rate(http_requests_total{status=~"5.."}[5m]))
  /
sum(rate(http_requests_total[5m])) * 100

# P95 latency
histogram_quantile(0.95,
  sum(rate(http_request_duration_seconds_bucket[5m])) by (le)
)

# CPU usage
100 - (avg(rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100)

# Memory usage
(1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes)) * 100

See references/quick_commands.md for Kubernetes, Elasticsearch, Loki, and CloudWatch query references.

---

Resources Summary

Scripts: alert_quality_checker.py | dashboard_generator.py | log_analyzer.py | slo_calculator.py

References: metrics_design.md | alerting_best_practices.md | logging_guide.md | tracing_guide.md | slo_sla_guide.md | tool_comparison.md | datadog_migration.md | dql_promql_translation.md

Templates: prometheus-alerts/webapp-alerts.yml | prometheus-alerts/kubernetes-alerts.yml | otel-config/collector-config.yaml | runbooks/incident-runbook-template.md