2 Commits

Author	SHA1	Message	Date
ZhenYi	8defac98ad	fix(observability): resolve tracing double-init runtime panic ... Both init_tracing_subscriber() and init_otlp() were calling try_init() on the global tracing dispatcher, causing "global default trace dispatcher has already been set" at runtime when APP_OTEL_ENABLED=true. Fix: simplify the API so init_tracing_subscriber() never installs the subscriber — it either calls try_init() immediately (non-OTLP mode) or returns without installing (OTLP mode, defer=true). init_otlp() now builds the complete subscriber stack (registry + env_filter + fmt_layer + otel_layer) and calls try_init() once. init_tracing_subscriber() signature: (level, defer) → () init_otlp() signature: (endpoint, service_name, _, log_level) → Result The fmt layer is replicated inside init_otlp() for the OTLP path.	2026-04-22 23:28:56 +08:00
ZhenYi	b4024aa690	feat(observability): Phase 6 OTLP tracing + Prometheus /metrics endpoint ... - Add HTTP OTLP exporter (opentelemetry-otlp 0.31) via SdkTracerProvider + BatchSpanProcessor + tracing_opentelemetry layer - Add Prometheus /metrics handler via metrics-exporter-prometheus 0.13 - Replace slog with tracing throughout: HttpMetrics, TracingSpanMiddleware - Replace .init() with .try_init() to allow OTLP layer registration after init_tracing_subscriber() - otlp.rs: SpanExporter::builder().with_http().with_endpoint(), Resource::builder().with_service_name(), .with_attribute(KeyValue::new(...)) - prometheus_exporter.rs: install_recorder(), prometheus_handler(), spawn_http_metrics_poller()	2026-04-21 22:28:15 +08:00