System Design Tools: Monitoring, Security & Testing
🔹 1. Monitoring Tools
Purpose: Track system health, performance metrics, resource usage.
| Tool | Type | Notes / Use Case |
|---|---|---|
| Prometheus | Metrics monitoring | Open-source, time-series DB, pulls metrics from exporters. |
| Grafana | Visualization | Works with Prometheus, InfluxDB, Elastic. Dashboards & alerts. |
| Datadog | SaaS monitoring | Full-stack monitoring, logs, APM, cloud-friendly. |
| New Relic | APM & metrics | Deep performance monitoring for apps and infrastructure. |
| Zabbix / Nagios | Infrastructure monitoring | Server & network monitoring. |
🔹 2. Logging Tools
Purpose: Collect, store, and query logs for debugging & auditing.
| Tool | Type | Notes / Use Case |
|---|---|---|
| ELK Stack (Elasticsearch, Logstash, Kibana) | Logs aggregation | Centralized logging + search + dashboards. |
| OpenSearch | Logs aggregation | Fork of Elasticsearch. |
| Fluentd / Fluent Bit | Log shipping | Collects logs from services to centralized storage. |
| Graylog | Log management | Real-time logging & alerting. |
| Splunk | Commercial | Powerful log analytics & dashboards. |
🔹 3. Alerting Tools
Purpose: Notify teams when metrics or logs indicate problems.
| Tool | Type | Notes / Use Case |
|---|---|---|
| Grafana Alerts | Metrics-based | Trigger alerts on thresholds & anomalies. |
| Prometheus Alertmanager | Metrics-based | Works with Prometheus metrics for alert routing. |
| PagerDuty | Incident management | Notification, escalation, on-call schedules. |
| OpsGenie | Incident management | Alerts, escalation policies, integrations. |
| Slack / MS Teams | Integration | Receive alerts from monitoring tools. |
🔹 4. Security Tools
Purpose: Protect services, data, access control, and detect threats.
| Tool | Type | Notes / Use Case |
|---|---|---|
| Vault (HashiCorp) | Secrets management | Store API keys, DB credentials, encryption keys. |
| AWS KMS / Azure Key Vault / GCP Secret Manager | Cloud secrets | Manage encryption keys & secrets in cloud. |
| OWASP ZAP / Burp Suite | Security testing | Web app vulnerability scanning. |
| Falco | Runtime security | Detect unexpected behavior in containers. |
| Snort / Suricata | IDS/IPS | Network intrusion detection & prevention. |
| Snyk / Dependabot | Dependency scanning | Detect vulnerabilities in code dependencies. |
| Security Groups / WAF | Network & app firewall | Protect servers & apps from unauthorized access. |
🔹 5. Observability Stack
Many teams combine Monitoring + Logging + Alerts + Tracing:
- Prometheus + Grafana → metrics & dashboards
- ELK / OpenSearch → logs & search
- Jaeger / Zipkin / OpenTelemetry → distributed tracing
- Alertmanager / PagerDuty → alerts & notifications
💡 Tip: Modern cloud-native apps often use a centralized observability platform like Datadog, New Relic, or Splunk, which combines metrics, logs, traces, and alerting in one place.
🔹 6. Testing Layers in a Distributed System
| Layer | Type of Testing | Notes / Tools |
|---|---|---|
| Unit Tests | Test individual functions / methods | Jest, Mocha, Jasmine, JUnit |
| Integration Tests | Test interactions between services or modules | Postman, Supertest, REST Assured |
| API / Contract Tests | Ensure APIs behave as expected | Postman, Pact (for contract testing) |
| End-to-End (E2E) Tests | Simulate user flows across the system | Cypress, Selenium, Playwright |
| Performance / Load Tests | Check system under heavy load | JMeter, Locust, k6 |
| Security Tests | Vulnerability scanning | OWASP ZAP, Burp Suite, Snyk |
| Monitoring Tests | Synthetic / uptime tests | Pingdom, Datadog Synthetics, Grafana Synthetic |
🎯 Best Practices for System Design
Monitoring Strategy
- Four Golden Signals: Latency, Traffic, Errors, Saturation
- SLA/SLO/SLI: Define clear service level objectives
- Distributed Tracing: Track requests across microservices
- Custom Metrics: Business-specific KPIs beyond infrastructure metrics
Security Layering
- Defense in Depth: Multiple security layers
- Zero Trust: Verify everything, trust nothing
- Principle of Least Privilege: Minimal necessary access
- Regular Security Audits: Continuous vulnerability assessment
Testing Pyramid
- 70% Unit Tests: Fast, isolated, comprehensive
- 20% Integration Tests: Service interactions
- 10% E2E Tests: Critical user journeys only
- Continuous Testing: Automated in CI/CD pipeline
🚀 Modern Stack Examples
Cloud-Native Stack
- Monitoring: Prometheus + Grafana + AlertManager
- Logging: Fluentd → Elasticsearch → Kibana
- Tracing: OpenTelemetry → Jaeger
- Security: Vault + Falco + OWASP ZAP
- Testing: Jest + Cypress + k6 + Snyk
Enterprise SaaS Stack
- All-in-One: Datadog or New Relic
- Security: Okta + CyberArk + Rapid7
- Testing: Selenium Grid + BlazeMeter + Veracode
- Incident Management: PagerDuty + ServiceNow
Startup/SMB Stack
- Monitoring: Grafana Cloud + Simple uptime monitors
- Logging: Centralized logging (cloud provider native)
- Security: Cloud provider security groups + basic WAF
- Testing: GitHub Actions + basic E2E testing