Enabling OpenTelemetry for a Rust Agent

The golem-otlp-exporter is a built-in plugin that exports agent telemetry (traces, logs, metrics) to any OTLP-compatible collector via OTLP/HTTP. No plugin installation is needed — just enable it in the application manifest.

Step 1 — Enable the Plugin in golem.yaml

Add the plugin to the component (or agent) that should emit telemetry:

components:
  my-app:service:
    plugins:
      - name: golem-otlp-exporter
        version: "1.5.8"
        parameters:
          endpoint: "http://localhost:4318"
          signals: "traces,logs,metrics"

Plugin Parameters

Step 2 — Deploy

golem deploy --yes

After deployment, newly created agents from this component automatically send telemetry to the configured collector.

What Gets Exported

Traces

Spans are created automatically for:

• Agent invocations
• RPC calls to other agents
• Outgoing HTTP requests

Trace and span IDs propagate from inbound HTTP requests (via code-first routes) and are included in outgoing HTTP request headers automatically.

Custom Spans

Use the golem::api::context bindings to create custom spans:

use golem_rust::bindings::golem::api::context;
 
let span = context::start_span("my-operation");
span.set_attribute("env", &context::AttributeValue::String("production".to_string()));
span.set_attributes(&[
    context::Attribute { key: "service".to_string(), value: context::AttributeValue::String("my-service".to_string()) },
    context::Attribute { key: "version".to_string(), value: context::AttributeValue::String("1.0".to_string()) },
]);
 
// ... do work ...
 
let ctx = context::current_context();
println!("trace_id: {}", ctx.trace_id());
span.finish();

Logs

When logs is included in signals, all log output is forwarded to the OTLP collector. See the golem-logging-rust skill for full logging guidance.

use log::debug;
 
println!("Hello from Rust!");
debug!("This is a debug log entry");

Metrics

When metrics is included in signals, exported metrics include the following non-exhaustive list:

These are emitted OTLP names. A backend such as Prometheus may normalize dots to underscores and add suffixes; use that backend’s mapping when writing queries.

Each metric includes service.name, golem.agent.id, golem.component.id, and golem.component.version attributes.

Export Semantics

• Durable Start, End, and Cancelled metadata drives span lifecycle. Long-lived spans retain their origin trace across invocations; failed or retrying attempts do not prematurely close the logical span. Logs use their recorded trace context.
• Stream summaries use bounded event/outcome metric labels and aggregate item counts; they do not emit a span per item. Active resource and memory values are gauges, and metric labels avoid resource IDs and payload values.
• In agent-type service-name mode, service.name excludes constructor parameters and phantom instance IDs; golem.agent.id remains the full identity.
• Collector export is best effort. Accepted source state advances when a send fails, and traces, logs, and metrics are still attempted independently. Exactly-once plugin batch delivery is not exactly-once collector delivery.
• Fork/revert cannot retract telemetry already accepted by a collector. Source deletion does not provide a terminal signal, so no successful close is invented. Switching plugin instances can lose open-span state; continuity is deferred to GOL-667.

Local Observability Stack

The Golem repository includes a ready-made Docker Compose setup at docker-examples/otlp-collector/:

docker compose -f docker-examples/otlp-collector/docker-compose.yml up -d

This starts:

• OTel Collector on port 4318 (OTLP/HTTP)
• Jaeger on http://localhost:16686  (traces)
• Prometheus on http://localhost:9090  (metrics)
• Loki via Grafana (logs)
• Grafana on http://localhost:3000  (admin/admin)

Configure the plugin with endpoint: "http://localhost:4318" to use this stack.

Per-Environment Configuration

Use presets to vary the endpoint across environments:

Use the environment selector app-env:production. A plain production custom preset can become the default custom preset when it is the only one, applying the production endpoint in every environment.

components:
  my-app:service:
    plugins:
      - name: golem-otlp-exporter
        version: "1.5.8"
        parameters:
          endpoint: "http://localhost:4318"
          signals: "traces,logs,metrics"
    presets:
      app-env:production:
        pluginsMergeMode: replace
        plugins:
          - name: golem-otlp-exporter
            version: "1.5.8"
            parameters:
              endpoint: "https://otel.prod.example.com:4318"
              headers: "x-api-key={{ OTLP_API_KEY }}"
              signals: "traces,logs,metrics"

Key Points

• Built-in — no golem plugin register needed, just add to golem.yaml
• Deploy required — run golem deploy after adding the plugin configuration
• Trace context propagates automatically through HTTP routes and RPC calls
• Use context::start_span from golem_rust::bindings::golem::api::context for custom spans
• Plugin can be activated/deactivated per agent with golem agent activate-plugin / golem agent deactivate-plugin

Related Guides

• Load golem-manage-plugins for the general plugin installation model (manifest sections, CLI commands, priority, per-environment configuration)