parse-otel-span-description.ts

import { AttributeValue, SpanKind } from '@opentelemetry/api';
import { Span as OtelSpan } from '@opentelemetry/sdk-trace-base';
import { SemanticAttributes } from '@opentelemetry/semantic-conventions';

interface SpanDescription {
  op: string | undefined;
  description: string;
}

/**
 * Extract better op/description from an otel span.
 *
 * Based on https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/7422ce2a06337f68a59b552b8c5a2ac125d6bae5/exporter/sentryexporter/sentry_exporter.go#L306
 *
 * @param otelSpan
 * @returns Better op/description to use, or undefined
 */
export function parseSpanDescription(otelSpan: OtelSpan): SpanDescription {
  const { attributes, name } = otelSpan;

  // if http.method exists, this is an http request span
  const httpMethod = attributes[SemanticAttributes.HTTP_METHOD];
  if (httpMethod) {
    return descriptionForHttpMethod(otelSpan, httpMethod);
  }

  // If db.type exists then this is a database call span.
  const dbSystem = attributes[SemanticAttributes.DB_SYSTEM];
  if (dbSystem) {
    return descriptionForDbSystem(otelSpan, dbSystem);
  }

  // If rpc.service exists then this is a rpc call span.
  const rpcService = attributes[SemanticAttributes.RPC_SERVICE];
  if (rpcService) {
    return {
      op: 'rpc',
      description: name,
    };
  }

  // If messaging.system exists then this is a messaging system span.
  const messagingSystem = attributes[SemanticAttributes.MESSAGING_SYSTEM];
  if (messagingSystem) {
    return {
      op: 'message',
      description: name,
    };
  }

  // If faas.trigger exists then this is a function as a service span.
  const faasTrigger = attributes[SemanticAttributes.FAAS_TRIGGER];
  if (faasTrigger) {
    return { op: faasTrigger.toString(), description: name };
  }

  return { op: undefined, description: name };
}

function descriptionForDbSystem(otelSpan: OtelSpan, _dbSystem: AttributeValue): SpanDescription {
  const { attributes, name } = otelSpan;

  // Use DB statement (Ex "SELECT * FROM table") if possible as description.
  const statement = attributes[SemanticAttributes.DB_STATEMENT];

  const description = statement ? statement.toString() : name;

  return { op: 'db', description };
}

function descriptionForHttpMethod(otelSpan: OtelSpan, httpMethod: AttributeValue): SpanDescription {
  const { name, kind } = otelSpan;

  const opParts = ['http'];

  switch (kind) {
    case SpanKind.CLIENT:
      opParts.push('client');
      break;
    case SpanKind.SERVER:
      opParts.push('server');
      break;
  }

  // Ex. description="GET /api/users/{user_id}".
  const description = `${httpMethod} ${name}`;

  return { op: opParts.join('.'), description };
}