[receiver/statsd] log only non-EOF errors when reading payload received via TCP

[bacherfl]

Description: This PR modifies the tcp server of the statsd receiver to log errors only if they are not an io.EOF, as this one is expected when the payload has been read completely.

Link to tracking Issue: #33951

Testing: The affected function has already been covered by existing tests. The only thing changed was whether to log the error or not.

Documentation: None required, as there have been no changes from user perspective

[crobert-1]

Have you been able to test to ensure the message is no longer logged for EOF?

[bacherfl]

Have you been able to test to ensure the message is no longer logged for EOF?

Yes, I did some manual testing to verify the message is not logged.
For testing, I used the following config:

receivers:
  statsd:
    endpoint: 0.0.0.0:8125
    transport: tcp

processors:

exporters:
  debug:
    verbosity: detailed

service:
  telemetry:
    metrics:
      address: 0.0.0.0:8888
    logs:
      level: debug
  pipelines:
    metrics:
      receivers: [statsd]
      exporters: [debug]

And sent a metric using the following command:

echo "test.metric:42|c|#myKey:myVal" | nc -w 100000 -4 -v localhost 8125;

Which resulted in the following logs:

2024-07-09T13:58:53.188+0200    debug   [email protected]/receiver.go:313 Beta component. May change in the future.       {"kind": "receiver", "name": "statsd", "data_type": "metrics"}
2024-07-09T13:58:53.188+0200    info    extensions/extensions.go:34     Starting extensions...
2024-07-09T13:58:53.195+0200    info    [email protected]/service.go:219 Everything is ready. Begin running and processing data.
2024-07-09T13:58:53.195+0200    info    localhostgate/featuregate.go:63 The default endpoints for all servers in components have changed to use localhost instead of 0.0.0.0. Disable the feature gate to temporarily revert to the previous default.   {"feature gate ID": "component.UseLocalHostAsDefaultHost"}
2024-07-09T13:58:53.195+0200    info    zapgrpc/zapgrpc.go:176  [core] [Server #1 ListenSocket #2]ListenSocket created  {"grpc_log": true}
2024-07-09T13:59:53.196+0200    debug   [email protected]/parser.go:265     initial TransformContext        {"kind": "processor", "name": "transform", "pipeline": "metrics", "TransformContext": {}}
2024-07-09T13:59:53.196+0200    info    MetricsExporter {"kind": "exporter", "data_type": "metrics", "name": "debug", "resource metrics": 1, "metrics": 1, "data points": 1}
2024-07-09T13:59:53.196+0200    info    ResourceMetrics #0
Resource SchemaURL: 
ScopeMetrics #0
ScopeMetrics SchemaURL: 
InstrumentationScope otelcol/statsdreceiver 0.9.0
Metric #0
Descriptor:
     -> Name: test.metric
     -> Description: 
     -> Unit: 
     -> DataType: Sum
     -> IsMonotonic: false
     -> AggregationTemporality: Delta
NumberDataPoints #0
Data point attributes:
     -> myKey: Str(myVal)
StartTimestamp: 2024-07-09 11:58:53.195052 +0000 UTC
Timestamp: 2024-07-09 11:59:53.196102 +0000 UTC
Value: 42
        {"kind": "exporter", "data_type": "metrics", "name": "debug"}

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.