monitoring-observability

$2b

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

• Actionable - If you can't act on it, don't alert

• Symptom-based - Alert on user experience, not components

• SLO-tied - Connect to business impact

• 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

• Top-down layout: Most important metrics first

• Color coding: Red (critical), yellow (warning), green (healthy)

• Consistent time windows: All panels use same time range

• Limit panels: 8-12 panels per dashboard maximum

• 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 &#x26; 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