feat: OTel distributed tracing (spans) via TracingChannel

[logaretm]

Summary

• Adds built-in OpenTelemetry span creation alongside existing metrics, subscribing to the same TracingChannel events
• Context propagation via bindStore on OTel's internal AsyncLocalStorage — enables automatic parent-child span relationships (e.g. MULTI → child command spans)
• Follows OTel semantic conventions for database spans (db.operation.name, db.query.text, db.namespace, error.type, db.response.status_code, db.operation.batch.size)

Spans emitted

Channel	Span Name	Kind	Config
node-redis:command	{COMMAND} (e.g. SET)	CLIENT	always (filterable)
node-redis:batch	MULTI / PIPELINE	CLIENT	always
node-redis:connect	redis connect	CLIENT	enableConnectionSpans
node-redis:connection:wait	redis connection:wait	INTERNAL	enableConnectionSpans

Config

OpenTelemetry.init({
  tracing: {
    enabled: true,
    tracerProvider?: TracerProvider,    // defaults to global
    includeCommands?: string[],
    excludeCommands?: string[],
    enableConnectionSpans?: boolean,   // default: false
  }
});

Context propagation

Uses the same bindStore workaround from otel-tracing-channel — accesses OTel's internal AsyncLocalStorage via context._getContextManager()._asyncLocalStorage and binds it to each TracingChannel's start sub-channel. Falls back to WeakMap-based span tracking when ALS is not accessible.

[Copilot]

Pull request overview

Adds OpenTelemetry distributed tracing support to the client package by creating spans from existing TracingChannel events, including optional connection-related spans and command filtering.

Changes:

• Introduces OTelTracing to subscribe to TracingChannel lifecycle events and emit OTel spans with Redis/db semantic attributes.
• Extends observability configuration/types to include tracing settings and adds db.operation.batch.size attribute key.
• Adds unit tests covering span creation, parent-child relationships, errors, filtering, and lifecycle.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/client/package.json	Adds OTel tracing-related devDependencies used by new tracing tests.
packages/client/lib/opentelemetry/types.ts	Adds TracingConfig and new batch-size attribute constant; wires tracing into ObservabilityConfig.
packages/client/lib/opentelemetry/tracing.ts	Implements OTelTracing span creation and context propagation via bindStore.
packages/client/lib/opentelemetry/tracing.spec.ts	Adds unit tests for span behavior (commands, batch, connection spans, errors, lifecycle).
packages/client/lib/opentelemetry/index.ts	Initializes tracing when enabled and re-exports tracing config/entrypoints.
package-lock.json	Updates lockfile for newly added devDependencies.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The new devDependencies @opentelemetry/context-async-hooks and @opentelemetry/sdk-trace-base require Node ^18.19.0 || >=20.6.0 (per their package engines), but this package advertises engines.node: >= 18. This can produce engine warnings/errors for contributors/CI pinned to Node 18.0–18.18; consider either bumping the supported Node engine range (e.g. to >=18.19) or using OTel devDependency versions compatible with Node 18.0.

[Copilot]

OTelTracing.init ignores config.enabled and silently no-ops when called multiple times, which is inconsistent with OpenTelemetry.init / OTelMetrics.init (they throw on re-init) and makes the enabled flag in TracingConfig misleading. Consider either (a) honoring config.enabled === false inside OTelTracing.init and throwing on double-init for consistency, or (b) removing enabled from TracingConfig and keeping the current behavior intentionally.

Suggested change

	if (OTelTracing.#initialized) return;
	if (OTelTracing.#initialized) {
	throw new Error('OTelTracing has already been initialized');
	}
	// If tracing is explicitly disabled via config, mark as initialized
	// but do not create an instance or subscribe to any channels.
	if (config?.enabled === false) {
	OTelTracing.#initialized = true;
	return;
	}