[Janaka2]

Motivation

• Provide observability-first examples by instrumenting selected patterns with OpenTelemetry (command latency, circuit-breaker metrics, saga correlation).
• Demonstrate resilience behaviour under fault-injection using Testcontainers + WireMock to show timeouts, partial failures and retry interactions.
• Ship minimal deployment scaffolding so pattern demos can run in containerized environments (compose + k8s + OTEL collector).

Description

• Add a new package org.example.cloudnative.observability with ObservedCommandExecutor, ObservedCircuitBreaker, CorrelatedSagaOrchestrator, and CorrelatedSagaStep to emit spans/metrics and propagate correlation IDs.
• Add tests ObservabilityPatternsTest (in-memory OpenTelemetry spans/metrics assertions using InMemorySpanExporter/InMemoryMetricReader) and ResilienceFaultInjectionTest (WireMock scenarios driven by Testcontainers to exercise timeouts and retries).
• Include deployment starter assets under deploy/: docker-compose.yml, otel-collector-config.yaml, and minimal deploy/k8s/ manifests for two demos.
• Update project docs (docs/phase-4-cloud-native-observability.md) and README.md phase tracking, and add OpenTelemetry/Testcontainers dependencies to pom.xml.

Testing

• Ran mvn test -DskipITs in this environment but the build failed early due to plugin/dependency resolution from Maven Central returning HTTP 403, so the full test suite could not be executed here.
• ObservabilityPatternsTest is designed to validate spans and metrics using in-memory OTEL testing helpers and asserts presence of command.execute, saga.orchestration spans and pattern.command.latency.ms metric.
• ResilienceFaultInjectionTest uses Testcontainers + WireMock and is guarded by assumeTrue(DockerClientFactory.instance().isDockerAvailable()), so it will auto-skip when Docker is not available in the runner.
• Recommendation: run mvn test in a networked environment with Docker available to validate all tests end-to-end.

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Codex Task