Ollygarden Otel JS Setup

JS/Node.js SDK Setup Conventions

Status decision: declarative vs programmatic

The @opentelemetry/configuration package is experimental. Default to declarative config for new projects. Use the programmatic NodeSDK fallback below if stability is critical or the project needs runtime configuration that YAML cannot express.

Setup Checklist — verify every item before you finish

Setup is not done when the SDK boots. Each unchecked item below produces a specific telemetry-quality finding in production; work through all of them.

• Do not export query strings or other user input. Telemetry must not capture data that can carry user input by default, and the query string is exactly that — yet the Node HTTP instrumentation (@opentelemetry/instrumentation-http, active through auto-instrumentations-node) exports it out of the box: url.query on server spans and folded inside url.full on client spans under the stable HTTP semantics. Check which semantic-convention mode your installed instrumentation actually emits — many contrib versions still default to the old HTTP attributes, where the query rides in http.target on server spans and inside http.url on client spans; redacting only the stable url.query/url.full keys then leaves the marker exposed. Only userinfo credentials are redacted by default; everything else — GET /owners?lastName=Smith, search terms, tokens pasted into links — goes out verbatim (Critical PII Leakage finding). Strip it in-process, before it leaves the application — overwrite or delete whichever attributes carry it in your mode (url.query/url.full, and/or http.target/http.url) in the HTTP instrumentation's own attribute hook (applyCustomAttributesOnSpan / startIncomingSpanHook) or in a span-processor / exporter wrapper that rewrites the attribute before export. A Collector transform/redaction processor is only defense-in-depth, never the sole control: the raw value has already crossed the process boundary and may sit in in-transit buffers, debug logs, or an alternate export path that skips the Collector. The route template (http.route, url.path) already answers "which endpoint"; if a specific parameter is genuinely needed as telemetry, capture it deliberately as a bounded, named attribute — never by keeping the raw query string. Leave the opt-in header-capture knobs (OTEL_INSTRUMENTATION_HTTP_CAPTURE_HEADERS_*) off for the same reason. Verify by sending a request with a known marker value in a query parameter and inspecting the exported span: the marker must not appear anywhere.

• Keep startup and other non-request work from polluting trace shapes. Auto instrumentation patches http, database drivers, and clients process-wide, so any outbound call made during boot — a migration, a warm-up HTTP request, a connection-pool probe — is emitted as a parentless CLIENT root span because no request context is active yet (Root Client Span finding). Two obligations: (1) either wrap deliberate startup work in an explicit application-startup span so those child spans have a parent, or suppress instrumentation for it (run it before startNodeSDK, or drop init-phase spans with a sampler / Collector rule) — do not ship detached CLIENT roots by default; (2) never build span names from unbounded input. Custom spans named with an id, a URL, or any per-request value (e.g. tracer.startSpan('job ' + jobId)) create unbounded span-name cardinality; name the span for the operation and put the varying value in a bounded attribute. Verify by booting the app and inspecting the first exported traces: no parentless CLIENT roots, and no per-request/per-boot identifiers anywhere in span names.

• Configure the SDK declaratively — one YAML document, not option sprawl. A scatter of OTEL_* flags plus hand-wired new NodeSDK({...}) exporter/processor code is the anti-pattern: operators cannot review or change the telemetry pipeline as a single document without a redeploy. Prefer the declarative model — startNodeSDK() from @opentelemetry/sdk-node loads the file named by OTEL_CONFIG_FILE through the experimental @opentelemetry/configuration package (mechanics: otel-js skill, references/declarative-setup.md; YAML conventions: ollygarden-otel-declarative-config). Keep the programmatic NodeSDK fallback only when stability is critical or the config needs runtime values YAML cannot express (see the status decision above). The file replaces option/env-based configuration — not code. Components that must run in code — the query-string redaction from the first item, the startup-span policy from the second, the disabled fs/dns/net instrumentations — stay in place and are passed to startNodeSDK(); going declarative does not discharge those items, and every earlier item's verification must be re-run after the switch. The file must also preserve the standard OTEL_* contract via ${ENV} substitution — the next item spells that out. Verify by changing a config value (e.g. the sampler argument or the exporter endpoint) in the YAML and confirming behavior changes with no code change and no rebuild.

• Honor the standard OTEL_* environment variables end-to-end. OTEL_EXPORTER_OTLP_*, OTEL_SERVICE_NAME, and OTEL_RESOURCE_ATTRIBUTES must all take effect at runtime. Do not invent custom variables (SERVICE_VERSION, DEPLOYMENT_ENVIRONMENT, ...) for values the standard variables already express, and never let a hardcoded default clobber an operator-supplied value. The programmatic NodeSDK reads these variables directly, but a declarative YAML loaded via OTEL_CONFIG_FILE does not — when the config file is set the SDK stops falling back to the environment, so each standard variable must be threaded in explicitly with substitution:

  resource:
    attributes:
      - name: service.name
        value: "${OTEL_SERVICE_NAME:-my-node-service}"
        type: string
    # standard deploy-time attributes (service.version,
    # deployment.environment.name, ...) arrive through the STANDARD variable:
    attributes_list: "${OTEL_RESOURCE_ATTRIBUTES}"
  

  Do not also hardcode a deploy-varying key (e.g. deployment.environment.name) under attributes, or the literal silently wins and misfiles every signal. Point the exporter at ${OTEL_EXPORTER_OTLP_ENDPOINT:-http://localhost:4318}. Verify by booting with all three standard variables set to non-default values: OTEL_SERVICE_NAME and OTEL_RESOURCE_ATTRIBUTES must land on the exported resource, while the overridden OTEL_EXPORTER_OTLP_ENDPOINT — a destination, not a telemetry attribute — is confirmed at the receiving collector, not on the spans.

• Keep the resource lean and add service.instance.id. The Node SDK's default detector set (envDetector, processDetector, hostDetector) does not include service.instance.id — the serviceinstance detector that would mint one is experimental and off by default — so unless you act, every process of a replicated service is indistinguishable (Missing service.instance.id finding). Add a per-process UUID (crypto.randomUUID()) alongside service.version: programmatically via resourceFromAttributes (the string key is service.instance.id, or ATTR_SERVICE_INSTANCE_ID from @opentelemetry/semantic-conventions/incubating), or in declarative YAML as a resource attribute fed a per-process value. Keep the rest of the resource minimal — service.name, service.version, service.instance.id, deployment.environment.name is the full set. Do not enable host/process/OS resource detectors that stamp discouraged process.* / os.* attributes (Discouraged Resource Attribute finding). Verify by inspecting the exported resource: service.instance.id is present and differs between two separate process starts, and no process.*/os.* attributes are attached.

Required: Verification Report

Setup is not complete until you produce this report. It is a table with one row per checklist item above. Fill each row with artifacts from THIS run — the marker value you sent, an excerpt of the exported span dump, a trace id, the config value you changed. Never a restatement of the requirement, never a bare "done".

The table below is an illustrative example, not a report you can submit: every value in it is a placeholder showing the expected shape of evidence. Replace every cell with your own run's artifacts. If you did not run a check, write GAP — not run in that row and leave it visible — a missing or hand-waved row is itself a finding.

Example (illustrative values — replace every cell with your own run's evidence):

A row you cannot fill with observed evidence is a visible gap — that item is not done. Do not delete the row, copy these example values, or write "N/A" to hide it; go run the check and record what you actually saw.

Dependencies

npm install @opentelemetry/api @opentelemetry/sdk-node @opentelemetry/configuration
npm install @opentelemetry/auto-instrumentations-node
npm install @opentelemetry/semantic-conventions

Fetch the latest versions of these packages (see the otel-js skill's Sources of Truth) and pin them in package.json as appropriate for your project.

Project Structure

src/
├── telemetry/
│   ├── constants.ts      # Service scope and telemetry constants
│   ├── setup.ts          # SDK initialization
│   └── index.ts          # Re-exports
├── index.ts              # App entry point (imports telemetry first)
configs/
└── otel.yaml             # Declarative configuration

Instrumentation File (src/telemetry/setup.ts)

import { startNodeSDK } from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';

// startNodeSDK loads OTEL_CONFIG_FILE and registers the configured providers.
// new NodeSDK(...) is the separate programmatic path and does not load the file.
export const sdk = startNodeSDK({
  instrumentations: [
    getNodeAutoInstrumentations({
      '@opentelemetry/instrumentation-fs': { enabled: false },
      '@opentelemetry/instrumentation-dns': { enabled: false },
      '@opentelemetry/instrumentation-net': { enabled: false },
    }),
  ],
});

Entry Point (src/index.ts)

// IMPORTANT: Import and start telemetry BEFORE any other imports
import { sdk } from './telemetry/setup';

import { app } from './app';

const PORT = process.env.PORT ?? 3000;
const server = app.listen(PORT, () => {
  console.log(`Server listening on port ${PORT}`);
});

process.on('SIGTERM', () => {
  server.close(async () => {
    await sdk.shutdown();
    process.exit(0);
  });
});

Fallback: Programmatic NodeSDK Setup

If declarative config is not suitable (e.g., need dynamic runtime config or older SDK version), use programmatic setup:

import { NodeSDK } from '@opentelemetry/sdk-node';
import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
import { OTLPMetricExporter } from '@opentelemetry/exporter-metrics-otlp-http';
import { OTLPLogExporter } from '@opentelemetry/exporter-logs-otlp-http';
import { PeriodicExportingMetricReader } from '@opentelemetry/sdk-metrics';
import { BatchLogRecordProcessor } from '@opentelemetry/sdk-logs';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { resourceFromAttributes, envDetector } from '@opentelemetry/resources';
import { ATTR_SERVICE_INSTANCE_ID } from '@opentelemetry/semantic-conventions/incubating';
import { randomUUID } from 'node:crypto';

// service.name / service.version / deployment.environment.name arrive through the standard
// OTEL_SERVICE_NAME and OTEL_RESOURCE_ATTRIBUTES variables (applied by envDetector below);
// do not invent custom vars for them. Mint only the per-process service.instance.id that no
// default detector provides.
const resource = resourceFromAttributes({
  [ATTR_SERVICE_INSTANCE_ID]: randomUUID(),
});

export const sdk = new NodeSDK({
  resource,
  // Only envDetector: honor the OTEL_* contract without stamping discouraged
  // process.* / os.* attributes from the default process/host detectors.
  resourceDetectors: [envDetector],
  traceExporter: new OTLPTraceExporter(),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new OTLPMetricExporter(),
    exportIntervalMillis: 30_000,
  }),
  logRecordProcessors: [
    new BatchLogRecordProcessor(new OTLPLogExporter()),
  ],
  instrumentations: [
    getNodeAutoInstrumentations({
      '@opentelemetry/instrumentation-fs': { enabled: false },
      '@opentelemetry/instrumentation-dns': { enabled: false },
      '@opentelemetry/instrumentation-net': { enabled: false },
    }),
  ],
});

Key Details

• Disable noisy instrumentations: fs, dns, and net instrumentations generate high volumes of low-value spans. Disable them unless specifically needed.
• SIGTERM handler: Always register a shutdown handler to flush buffered telemetry before the process exits.

Cross-References

• Reference: otel-js skill — references/declarative-setup.md for the package version fetch table, activation, ESM/CJS rules, v2.0 migration facts.
• General conventions: ollygarden-otel-declarative-config — anti-patterns and common YAML patterns.