Observability: OpenTelemetry "Traces" with gRPC issue #51863

snovak7 · 2026-08-19T14:18:43Z

snovak7
Aug 19, 2026

So I have setup the environment with some effort where I enabled all 3 Open Telemetry sides Logs, Metrics, Traces

All plays nicely, I get all the data, but Quarkus still sends logs that it couldn't export the data over grpc channel, even though the data is received on the ingestion side

2026-08-19 14:11:14,745 traceId=, parentId=, spanId=, sampled= WARNING [io.quarkus.opentelemetry.runtime.exporter.otlp.sender.VertxGrpcSender] (vert.x-eventloop-thread-1) Failed to export TraceRequestMarshalers. Perhaps the collector does not support collecting traces using grpc? Try configuring 'quarkus.otel.exporter.otlp.traces.protocol=http/protobuf'
2026-08-19 14:11:15,423 traceId=, parentId=, spanId=, sampled= WARNING [io.quarkus.opentelemetry.runtime.exporter.otlp.sender.VertxGrpcSender] (vert.x-eventloop-thread-0) Failed to export LogsRequestMarshalers. Perhaps the collector does not support collecting traces using grpc? Try configuring 'quarkus.otel.exporter.otlp.traces.protocol=http/protobuf'
2026-08-19 14:11:33,320 traceId=, parentId=, spanId=, sampled= WARNING [io.quarkus.opentelemetry.runtime.exporter.otlp.sender.VertxGrpcSender] (vert.x-eventloop-thread-0) Failed to export MetricsRequestMarshalers. Perhaps the collector does not support collecting traces using grpc? Try configuring 'quarkus.otel.exporter.otlp.traces.protocol=http/protobuf'

Additionally this goes through 2 reverse proxies

Cloudflare with gRPC enabled through a cloudflared tunnel to
nginx-light grpc proxy

before reaching OpenObserve grpc (h2c) endpoint

Maybe I'm just missing some tiny detail here.

Thank you!

4nass · 2026-08-22T12:44:50Z

4nass
Aug 22, 2026

gRPC over multiple proxy layers (Cloudflare $\rightarrow$ NGINX $\rightarrow$ OpenObserve) is notoriously fragile due to how gRPC handles HTTP/2 trailers and keep-alive frames.

The official OpenTelemetry specification recommends http/protobuf over port 4318 when passing through traditional HTTP proxies or CDN layers. It is functionally identical to gRPC (uses the exact same Protobuf payloads), but uses standard HTTP/1.1 or HTTP/2 POST requests without requiring persistent gRPC streams or trailer passthrough.

Use Keycloak's native configuration properties (KC_TELEMETRY_* or CLI options)
Configuration via Environment Variables:

# Set OTLP Protocol to HTTP/Protobuf for ALL signals (Traces, Metrics, Logs)
KC_TELEMETRY_PROTOCOL=http/protobuf

# Set the base OTLP HTTP Endpoint (Port 4318)
KC_TELEMETRY_ENDPOINT=https://otel.yourdomain.com:4318

or via CLI Flags:

bin/kc.sh start \
  --tracing-enabled=true \
  --telemetry-logs-enabled=true \
  --metrics-enabled=true \
  --telemetry-protocol=http/protobuf \
  --telemetry-endpoint=https://otel.yourdomain.com:4318

1 reply

snovak7 Aug 25, 2026
Author

Thank you for the information, I will check this and report back

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Observability: OpenTelemetry "Traces" with gRPC issue #51863

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Observability: OpenTelemetry "Traces" with gRPC issue #51863

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4nass Aug 22, 2026

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snovak7 Aug 25, 2026 Author

snovak7
Aug 19, 2026

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4nass
Aug 22, 2026

snovak7 Aug 25, 2026
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