Choosing Between New Relic Java Agent and OpenTelemetry for Spring Boot: A Practical Decision Framework

The Real Problem: Instrumentation Strategy Isn't Just About Traces

You're running a Spring Boot microservice and need observability. The question isn't whether to instrument—it's whether to lean on New Relic's Java agent (v8+) for zero-code auto-instrumentation or invest in OpenTelemetry's vendor-neutral approach with manual API calls for business logic. Both get traces into New Relic. The difference shows up in operational overhead, migration flexibility, and what happens when you need infinite tracing or custom metric alerting.

Takeaway: Start with the New Relic agent for fastest time-to-value on Spring Boot. Migrate to OpenTelemetry incrementally only when you need vendor portability or have a collector pipeline already running.

What You Get Out of the Box

The New Relic Java agent (v8+) auto-instruments Spring Boot, JDBC, HTTP clients (RestTemplate, WebClient), and Kafka producers/consumers without code changes. It emits spans, metrics, and logs, plus JVM metrics (GC, heap, threads) automatically. The OpenTelemetry Java agent via OTLP exporter covers similar libraries but requires explicit configuration of exporters, resource attributes, and span processors. New Relic's OTLP endpoint accepts traces, metrics, and logs but doesn't yet auto-apply NR-specific semantic conventions like nr.entityType.

Overhead is comparable: ~2-5% CPU and ~50-100 MB heap for either agent in typical Spring Boot apps. OpenTelemetry's varies more with sampler and exporter configuration.

Where Manual Work Is Unavoidable

Custom business logic—checkout flows, payment validation, domain-specific operations—requires manual instrumentation regardless of agent choice. With the New Relic agent, you add @Trace annotations that mix seamlessly with auto-instrumented spans. With OpenTelemetry, you use the OpenTelemetry API (SpanBuilder, Tracer) directly. The New Relic path keeps all spans in one agent; the OpenTelemetry path keeps instrumentation vendor-neutral but adds a dependency on the OTel API jar.

Worked Example: Running Both Agents During Migration

You can run both agents simultaneously to compare coverage before cutting over. Configure the New Relic agent normally (-javaagent:/path/to/newrelic.jar). Add the OpenTelemetry agent with OTLP exporter pointing to New Relic's endpoint:

-javaagent:/path/to/opentelemetry-javaagent.jar \
-Dotel.exporter.otlp.endpoint=https://otlp.nr-data.net:4317 \
-Dotel.exporter.otlp.headers=api-key=YOUR_LICENSE_KEY \
-Dotel.resource.attributes=service.name=my-service,deployment.environment=prod

Critical: disable distributed tracing on one agent to avoid duplicate trace IDs and span export storms. Set newrelic.distributed_tracing.enabled=false in newrelic.yml for the New Relic agent, or otel.propagators=tracecontext,baggage (without newrelic) for the OTel agent. Compare span coverage in New Relic UI under Distributed Tracing > Spans. Once parity is reached, disable the New Relic agent.

Infinite Tracing and Alerting: The Hidden Costs

New Relic's Infinite Tracing (tail-based sampling via Trace Observer) is built into the New Relic agent—configure infinite_tracing.trace_observer.host and you're done. With OpenTelemetry, you need a separate collector with the tail-sampling processor, adding infrastructure complexity. That collector must be managed, scaled, and monitored separately.

For alerting on custom metrics: the New Relic agent exposes Micrometer meters automatically into NRDB for NRQL alerting. OpenTelemetry metrics need a Prometheus exporter + Prometheus OpenMetrics integration, or an OTLP metric pipeline, to appear in NRDB. That's an extra pipeline to maintain.

Limitations and Guardrails

• Java version: New Relic agent 8.x+ requires Java 8+. Legacy Java 6/7 apps must use agent 7.x (EOL) or switch to OpenTelemetry.
• Attribute naming: OpenTelemetry semantic conventions (http.route, db.statement) differ from New Relic's legacy attribute names. Dashboard and query breakage during migration is likely unless you apply attribute mapping rules in the OTLP pipeline.
• Free tier quota: New Relic's free tier ingests 100 GB/month. High-cardinality custom attributes from either path can exceed quota quickly—enforce attribute allowlists.
• Dual-agent overhead: Running both agents doubles instrumentation overhead. Only do this temporarily during migration.

Decision Checklist

1. If you're on Spring Boot, Java 8+, and want fastest time-to-value with Infinite Tracing included: use New Relic Java agent.
2. If you need vendor portability, already run an OpenTelemetry Collector, or have a mandate for CNCF-standard instrumentation: use OpenTelemetry agent + OTLP exporter.
3. If migrating: run both agents temporarily with distributed tracing disabled on one, compare span coverage in NR UI, then cut over.
4. Enforce attribute allowlists on day one to protect ingest quota.

Verify your choice by deploying a sample Spring Boot app with the New Relic agent first—confirm auto-instrumented spans appear in Distributed Tracing > Spans. Then add the OpenTelemetry agent and compare attribute names side by side. Check New Relic agent release notes (docs.newrelic.com) for current supported frameworks before production rollout.