Lab: OpenTelemetry logs correlated with traces and file collection

What you will learn in this TP

• Connect an existing logger to OpenTelemetry
• Correlate logs and traces
• Collect files with filelog

Introduction #

What you will learn in this section

• Connect an existing logger to OpenTelemetry
• Correlate logs and traces
• Collect files with filelog

Context. Billing logs are text files nobody links to traces. You connect the modern service to OpenTelemetry and collect the legacy application's logs without changing it.

Prerequisites: Docker and Python 3.10 or later; the grafana/otel-lgtm stack (Collector, Tempo, Loki, Prometheus, Pyroscope and Grafana in one container)  ·  Estimated time: 45 min

Structured logs correlated with traces, from both collection paths.

Hands-on #

Guided steps, with their solution.

1. 1. Start the observability stack

   Why? A single image provides an OTLP Collector and every backend: focus on the signal.

   Start grafana/otel-lgtm, create a Python environment and point exporters to OTLP/HTTP port 4318.

2. 2. Connect the logging module

   Why? The LoggingHandler turns each logging call into an OpenTelemetry LogRecord, with the active trace context.

   Write facturation.py: a LoggerProvider with OTLP exporter, a handler added to the root logger, a TracerProvider, and INFO and ERROR logs emitted inside spans.

3. 3. Query and correlate in Grafana

   Why? The trace_id carried by each log lets you jump from the log to the trace and back.

   In Explore > Loki, show the service's errors, expand a line and spot trace_id, span_id, severity and your attributes. Open the linked trace, then from a Tempo span show its logs.

4. 4. Collect a legacy application's logs

   Why? Without touching code, the filelog receiver reads files and parses JSON, severity and trace context.

   Generate a JSON log file, then run a contrib Collector on the same network as the stack, with filelog, json_parser, trace_parser and a resource processor setting service.name.

5. 5. Reduce and mask

   Why? The Collector removes noise and personal data before storage.

   Add a filter processor dropping INFO logs and a transform masking e-mail addresses in the body, then check in Loki.

Difficulty level : ●●●○○ (3/5)