How to use OpenCensus packages in Node.js

tracing.ts

import { CoreTracer, Span, Tracer } from "@opencensus/core";
import { StackdriverTraceExporter } from "@opencensus/exporter-stackdriver";
import { TracingBase } from "@opencensus/nodejs-base";
import { TraceContextFormat } from "@opencensus/propagation-tracecontext";
import { Request } from "express";
import { ServerResponse } from "http";

function getOperationName(req: Request): string | undefined {
  if (req.baseUrl === "/graphql" && req.method === "POST") {
    return req.body.operationName;
  }
}

class Tracing extends TracingBase {
  public readonly tracer: Tracer;

  constructor() {
    super([]); // Default list of target modules to be instrumented
    this.tracer = new CoreTracer();
  }
}

function startTracing() {
  const propagation = new TraceContextFormat();

  const encoded = process.env.JSON_KEY_BASE64;
  const projectId = process.env.PROJECT_ID;
  let exporter: StackdriverTraceExporter;

  if (encoded && projectId) {
    const credentials = JSON.parse(Buffer.from(encoded, "base64").toString());
    exporter = new StackdriverTraceExporter({ projectId, credentials });
  }

  const tracing = Tracing.instance;
  const httpConfig = {
    ignoreIncomingPaths: ["/ping"],
    applyCustomAttributesOnSpan(span: Span, req: Request, _res: ServerResponse) {
      if (req) {
        const operationName = getOperationName(req);
        if (operationName) {
          span.addAttribute("graphql.operation_name", operationName);
        }
      }
    },
  };

  tracing.start({
    propagation,
    exporter,
    defaultAttributes: { commit_hash: process.env.COMMIT_HASH },
    plugins: {
      http: {
        module: "@opencensus/instrumentation-http",
        config: httpConfig,
      },
      https: {
        module: "@opencensus/instrumentation-https",
        config: httpConfig,
      },
      http2: {
        module: "@opencensus/instrumentation-http2",
        config: httpConfig,
      },
      grpc: "@opencensus/instrumentation-grpc",
    },
  });

  tracing.tracer.registerSpanEventListener({
    onStartSpan(span) {
      span.addAttribute("request_id", span.traceId);
    },
    onEndSpan(_span) {
      // noop
    },
  });

  return tracing;
}

export const tracing = startTracing();