1. OAuth 2.xhistorical

    Delegated authorization with resource owner, client, authorization server, resource server, scopes, access tokens, and secure redirect flows.

  2. Designing a Configuration Centerhistorical

    Versioned configuration distribution with environments, validation, watches, rollout, caching, security, and rollback.

  3. Designing Load Balancinghistorical

    Endpoint discovery, selection algorithms, health/outlier detection, connection reuse, locality, weighting, and overload-aware routing.

  4. Designing a Service Registryhistorical

    Service membership registration, discovery, leases/health, staleness, replication, client caches, and failure handling.

  5. Designing an API Gatewayhistorical

    Gateway routing and cross-cutting policy with authentication, limits, deadlines, observability, resilience, and safe ownership boundaries.

  6. Designing an Observability Systemhistorical

    Metrics, logs, traces, events, SLOs, correlation, storage, alerting, dashboards, and cost/cardinality control.

  7. Designing Distributed Tracinghistorical

    Trace/span context propagation, sampling, storage, causality, asynchronous work, and correlation with metrics/logs.

  8. Designing Resilience Componentshistorical

    Timeouts, deadlines, retries, circuit breakers, bulkheads, rate limits, load shedding, fallbacks, and idempotency.

  9. Designing Logginghistorical

    Structured logs, severity, correlation, context, sampling, retention, privacy, and operational querying.

  10. Designing Metrics Monitoringhistorical

    Metric naming/types, labels, cardinality control, RED/USE signals, SLOs, aggregation, and alerting.