OTel Logs

Table of Contents

Enable debug

The OTel Collector periodically retrieves metrics, traces, and logs, then forwards them to the observability platform. If you encounter missing data, enabling its debug mode can provide a more detailed output in the otelcol-$timestamp.log file. This additional verbosity offers deeper insights into MetricsHub operations, including initialization, pipeline processes, and termination workflows

Enable debug

First set the log level to debug in the otel/otel-config.yaml file:

service:
  telemetry:
    logs:
      level: debug
  extensions: [health_check]
  pipelines:
  # [...]

Then, restart MetricsHub for these new settings to be considered.

Finally, check the logs/otelcol-<timestamp>.log file, where <timestamp> is the time at which the log was started.

Note: The logs/otelcol-<timestamp>.log file is reset each time the Collector is started. Previous logs are identified with the <timestamp> value (ex: otelcol-2022-09-19-02-05-18.log). MetricsHub rotates the otelcol-<timestamp>.log file when it reaches a maximum size of 100MB and retains old log files for 2 days.

What to look for in otelcol-<timestamp>.log

First check that the MetricsHub Agent successfully launched the OpenTelemetry Collector.

Then check that the exporters and processors properly started.

Finally look for any connection issues or authentication failures to the configured observability platform(s) (Datadog, BMC Helix, Prometheus, Grafana, etc.).

Get more details about the exported data

You can enable the debug exporter in the otel/otel-config.yaml file to check which metrics, labels, and values are sent by the Collector to the observability platforms and verify that the configured processors did not alter the collected data.

First, list the debug exporter under the exporters section and set verbosity to detailed:

exporters:
# [...]
  debug:
    verbosity: detailed

Then, declare the debug exporter in the pipeline:

service:
  pipelines:
    metrics:
      receivers: # receivers
      processors: # processors
      exporters: [prometheusremotewrite/your-server,debug] # <-- added debug

Restart the Collector for the new settings to be considered.

The metric name, its labels and value are listed in the logs/otelcol-<timestamp>.log file.

Important: Disable the debug exporter when unused as its operation may affect the overall performance of the Collector and fill your file system.

Reduce the amount of information logged

To reduce the amount of information logged, you can configure the filter processor to only log metrics of specific hosts. In the example below, we configured the filter/keep1HostOnly processor to only log information about systems whose hostname contains my-server.big-corp.com:

processors:
  filter/keep1HostOnly:
    metrics:
      include:
        match_type: expr
        expressions:
        - Label("host.name") == "my-server.big-corp.com"

We then declared the filter/keep1HostOnly processor in the pipeline and restarted the Collector:

service:
  pipelines:
    metrics:
      receivers: [otlp, prometheus/internal]
      processors: [memory_limiter,batch,filter/keep1HostOnly] # <-- added filter
      exporters: # exporters

Important: Remove the filter processor from your pipeline once the troubleshooting is completed.

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