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go-caatsm/docs/observability.md
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## Observability
### Metrics
The service exposes Prometheus metrics via the monitoring HTTP server (default `:2112`):
- `caatsm_messages_total{stream,consumer,result}`
Total number of messages handled by the receiver, labelled by stream/consumer and result (`ok`, `fail`, `permanent_fail`, `retry`).
- `caatsm_handle_latency_seconds{stream,consumer}`
End-to-end handling latency from NATS receive to handler completion.
- `caatsm_retries_total{stream,consumer,reason}`
Number of retries (NAKs) issued by the consumer, labelled by reason (e.g. `processor_error`).
- `caatsm_js_api_calls_total{operation}`
JetStream API calls performed by the service.
- `caatsm_db_queries_total{operation,result}`
Database operations grouped by operation (`insert_one`, `insert_batch`, `insert_raw`) and result (`ok`, `error`).
- `caatsm_db_query_latency_seconds{operation}`
DB operation latency.
Additional OTEL metrics are emitted via the configured OTEL endpoint, including:
- `caatsm_messages_processed_total`
- `caatsm_parse_duration_ms`
- `caatsm_publish_failures_total`
- `caatsm_nats_consumer_ack_pending`
- `caatsm_nats_consumer_redelivered`
- `caatsm_nats_consumer_pending`
- `caatsm_nats_consumer_delivered`
These metrics are intended to be scraped by Prometheus (either directly or via the OTEL collector) and visualised in Grafana dashboards. Recommended dashboard panels include:
- Per-stream/consumer message rate and error rate.
- Handling latency P50/P95/P99.
- NATS consumer backlog and redelivery counts.
- DB query rates and latencies.
#### CAATSM Receiver Overview Dashboard
The `caatsm-overview` Grafana dashboard (provisioned from `configs/grafana-dashboards.dev/caatsm-overview.json`) focuses on the CAATSM receiver service and surfaces:
- **Message throughput by result** derived from `caatsm_messages_total{result}`.
- **Per stream/consumer rates** `caatsm_messages_total{stream,consumer}`.
- **End-to-end handle latency** P50/P95/P99 from `caatsm_handle_latency_seconds_bucket`.
- **DB query rate and latency** from `caatsm_db_queries_total` and `caatsm_db_query_latency_seconds_bucket`.
- **Retry and permanent failure rates** from `caatsm_retries_total` and `caatsm_messages_total{result="permanent_fail"}`.
- **Publish failures** from `caatsm_publish_failures_total`.
### Health and Readiness
The monitoring server exposes:
- `/healthz` basic liveness and dependency check.
- `/readyz` readiness endpoint with the same logic as `/healthz`, intended for load balancers / orchestrators.
Checks performed:
- PostgreSQL: `pgxpool.Pool.Ping` with configurable timeout (`monitoring.health_timeout`).
- NATS: connection status must be `CONNECTED`.
A non-200 response indicates the service is not healthy/ready and should be removed from traffic.
### Tracing
Tracing is configured via the `telemetry` section:
- `telemetry.enabled` enables OTEL exporters.
- `telemetry.endpoint` OTLP HTTP endpoint (e.g. `localhost:4318`).
- `telemetry.insecure` disables TLS for local/dev.
Key spans:
- `caatsm/nats`
- `Consumer.processMessage`
- `caatsm/app`
- `MessageProcessor.Handle`
- `Publisher.Publish`
- `caatsm/postgres`
- `Repository.InsertOne`
- `Repository.InsertBatch`
- `Repository.InsertRaw`
Important attributes:
- `nats.subject`, `nats.msg_id`, `nats.js.stream_seq`, `nats.js.consumer_seq`
- `telegram.message_id`, `telegram.category`, `telegram.status`
- `db.table`, `db.inserted`
### Structured Logging Contract
Logging is done with Zap. The `internal/observability/logging` package standardises fields via `MessageFields`:
- `service` logical component (`caatsm-consumer`, `caatsm-processor` etc.).
- `transport_msg_id` NATS/envelope message ID (derived from `Nats-Msg-Id` or JetStream sequence).
- `telegram_message_id` business telegram message ID from the payload.
- `category` telegram category (ARR, DEP, FPL, etc.).
- `stream`, `consumer`, `subject` JetStream context.
- `nats_sequence` JetStream stream sequence, when available.
- `request_id`, `trace_id` correlation identifiers.
- `error_type` high-level classification:
- `business` payload/validation/domain issues; not suitable for retry.
- `transient` network/DB/NATS glitches that may succeed on retry.
- `fatal` programming errors, schema mismatches, or configuration issues requiring operator attention.
Handler and consumer logs should always be emitted through `WithMessageContext` to ensure these fields are present where applicable.