Phase 2: The OBI Magic

2. Understand the OBI Config

The OBI Configuration File #

Open obi-config.yaml (already in the repo) to understand how OBI discovers and instruments your services:

cat ~/workshop/obi/02-obi-docker/obi-config.yaml

discovery:
  instrument:
    - name: "frontend"
      open_ports: 3000
    - name: "order-processor"
      open_ports: 8080
    - name: "payment-service"
      open_ports: 8081

ebpf:
  context_propagation: all

otel_traces_export:
  endpoint: http://localhost:4318

How Each Section Works #

discovery.instrument tells OBI how to find your services and what to name them. It matches processes by the ports they listen on, then assigns the name as the service.name attribute in the generated traces. Without this, OBI would use the executable path as the service name (e.g. /usr/local/bin/order-processor).

context_propagation: all is the key to distributed tracing. OBI injects Traceparent headers into outgoing HTTP requests at the kernel level. This is how a trace started in frontend connects through order-processor to payment-service even though none of these services know anything about tracing.

otel_traces_export.endpoint tells OBI where to send traces. Because OBI uses network_mode: host, localhost:4318 reaches the collector’s port that is mapped to the host in the compose file.