Load Generator fails to connect to Frontend Proxy causing no telemetry data flow

[ignaciopadron]

Description
I'm experiencing connectivity issues between the Load Generator and Frontend Proxy components in the OpenTelemetry Demo, which prevents telemetry data from being generated and flowing through the observability pipeline.

Environment

• Kubernetes cluster (k3s)
• OpenTelemetry Demo version: 2.0.2
• Helm chart version: 0.37.1

Problem
The Load Generator pod is consistently failing to connect to the Frontend Proxy with net::ERR_CONNECTION_REFUSED errors. This prevents the generation of telemetry data (traces, metrics, logs) that should flow through the observability pipeline.

Steps to Reproduce

1. Deploy OpenTelemetry Demo using Helm
2. Check Load Generator logs: kubectl logs -n otel-demo load-generator-xxx
3. Observe continuous Failed to load resource: net::ERR_CONNECTION_REFUSED errors

Expected Behavior

• Load Generator should successfully connect to Frontend Proxy
• Telemetry data should be generated and sent to OTel Collector
• Traces should flow through the pipeline: OTel Collector → Vector Producer → Kafka → Vector Consumer → Datadog Agent

Actual Behavior

• Load Generator cannot establish connection to Frontend Proxy
• No telemetry data is generated
• Pipeline remains empty with no traces appearing in Datadog

Investigation Results

• Frontend Proxy pod is running and healthy
• Service configuration appears correct (port 8080)
• Load Generator environment variables are properly set (LOCUST_HOST: http://frontend-proxy:8080)
• Network connectivity between pods in the same namespace should work
• Issue persists even after pod restarts

Logs
Load Generator logs:

Failed to load resource: net::ERR_CONNECTION_REFUSED
Failed to load resource: net::ERR_CONNECTION_REFUSED

Frontend Proxy logs show normal startup but no incoming connections:

[2025-07-11 17:56:06.909][8][info][config] loading 1 listener(s)
[2025-07-11 17:56:06.937][8][info][config] all dependencies initialized. starting workers

Additional Context

• This issue prevents the demo from generating realistic telemetry data
• The observability pipeline (OTel → Vector → Kafka → Datadog) is properly configured but receives no data due to this connectivity issue
• All other components (OTel Collector, Vector, Kafka, Datadog) are running correctly

Questions

1. Is there a known issue with Load Generator connectivity in recent versions?
2. Are there specific network requirements or configurations needed for Load Generator to Frontend Proxy communication?
3. Could this be related to the Envoy proxy configuration in the Frontend Proxy component?