rusmes-metrics

Observability and metrics collection for RusMES. Provides lock-free Prometheus-compatible metrics using AtomicU64 counters and gauges.

Status

Complete. The MetricsCollector is fully implemented with 18 metrics across SMTP, IMAP, JMAP, mail processing, queue, and storage categories.

Architecture

MetricsCollector (Clone, Send, Sync)
  |-- Arc<AtomicU64> for each metric (lock-free)
  |-- inc_*() methods for counters
  |-- set_*() methods for gauges
  '-- export_prometheus() -> String (text format)

Metrics

SMTP

Metric	Type	Description
`rusmes_smtp_connections_total`	Counter	Total SMTP connections accepted
`rusmes_smtp_messages_received_total`	Counter	Total messages received via SMTP
`rusmes_smtp_messages_sent_total`	Counter	Total messages relayed outbound
`rusmes_smtp_errors_total`	Counter	Total SMTP errors

IMAP

Metric	Type	Description
`rusmes_imap_connections_total`	Counter	Total IMAP connections
`rusmes_imap_commands_total`	Counter	Total IMAP commands processed
`rusmes_imap_errors_total`	Counter	Total IMAP errors

JMAP

Metric	Type	Description
`rusmes_jmap_requests_total`	Counter	Total JMAP API requests
`rusmes_jmap_errors_total`	Counter	Total JMAP errors

Mail Processing

Metric	Type	Description
`rusmes_mail_processed_total`	Counter	Total mail processed through pipeline
`rusmes_mail_delivered_total`	Counter	Total mail delivered to local mailboxes
`rusmes_mail_bounced_total`	Counter	Total bounce messages generated
`rusmes_mail_dropped_total`	Counter	Total mail dropped (Ghost state)

Queue

Metric	Type	Description
`rusmes_queue_size`	Gauge	Current number of messages in queue
`rusmes_queue_retries_total`	Counter	Total queue retry attempts

Storage

Metric	Type	Description
`rusmes_mailboxes_total`	Gauge	Total mailboxes
`rusmes_messages_total`	Gauge	Total stored messages
`rusmes_storage_bytes`	Gauge	Total storage usage in bytes

Usage

use rusmes_metrics::MetricsCollector;

let metrics = MetricsCollector::new();
metrics.inc_smtp_connections();
metrics.inc_smtp_messages_received();
metrics.set_queue_size(42);

let prometheus_text = metrics.export_prometheus();
// Returns Prometheus text exposition format

Dependencies

rusmes-proto - Mail type for record_mail_completed()
prometheus (declared, custom implementation used)
opentelemetry (declared, for future tracing integration)

Tests

cargo test -p rusmes-metrics   # 2 tests

rusmes-metrics 0.1.1