elsa-core/src/modules/Elsa.Diagnostics.OpenTelemetry

Elsa Diagnostics OpenTelemetry

Provides the OpenTelemetry diagnostics collector surface for Elsa hosts.

This module owns the Core-side OTEL contracts, HTTP/protobuf ingestion, bounded in-memory diagnostics store, feature registration, permissions, read APIs, live update hub, and collector metadata that Studio consumes.

Scope

Elsa.Diagnostics.OpenTelemetry is collector/read-side diagnostics infrastructure. It does not create workflow spans, mutate Activity.Current, export telemetry to vendors, or provide durable OpenTelemetry persistence. Workflow telemetry production remains owned by existing Elsa.Workflows ActivitySource and Meter instrumentation.

The historical Elsa.OpenTelemetry module from elsa-extensions is intentionally not ported into this feature. It is producer-side workflow tracing middleware, duplicates current Elsa.Workflows instrumentation, and mutates Activity.Current; this module is collector/read-side diagnostics infrastructure.

Routes

OTLP HTTP/protobuf ingestion is exposed under OpenTelemetryDiagnosticsOptions.HttpEndpointPath, which defaults to /elsa/otlp/v1:

• POST /elsa/otlp/v1/traces
• POST /elsa/otlp/v1/metrics
• POST /elsa/otlp/v1/logs

Diagnostics read APIs are exposed through Elsa API endpoints:

• POST /diagnostics/opentelemetry/resources/search
• POST /diagnostics/opentelemetry/traces/search
• GET /diagnostics/opentelemetry/traces/{traceId}
• POST /diagnostics/opentelemetry/metrics/search
• POST /diagnostics/opentelemetry/logs/search
• GET /diagnostics/opentelemetry/storage
• GET /diagnostics/opentelemetry/collector-configuration

Live updates are exposed through SignalR at OpenTelemetryDiagnosticsOptions.HubRoute, which defaults to /elsa/hubs/diagnostics/opentelemetry.

Security

All diagnostics read APIs require the OpenTelemetry diagnostics read permission. OTLP ingestion allows unauthenticated loopback traffic by default for local development only when no API key is configured. When OpenTelemetryDiagnosticsOptions.ApiKey is set, every sender must provide the configured API key header, including loopback senders.

Collector configuration returns endpoint and required-header names only. It never returns secret header values.

Storage

The default provider is bounded in-memory storage. Capacity options cover traces, spans, metric points, OTLP log records, and live subscriber queues. When a buffer exceeds capacity, the oldest item for that signal is dropped and diagnostics counters are incremented.