javascript - 在 express / nodejs 中创建和结束跟踪跨度的正确方法

Question

我正在尝试尝试Opentelemetry.js nodejs/express 库，并试图从 Istio 重写Sample的评论应用程序。bookinfo

我遵循了示例中给出的跟踪器配置：

我的请求处理程序为：

router.get('/:productIdStr', function(req, res, next) {
    starsReviewer1 = -1
    starsReviewer2 = -1
      var productId = parseInt(req.params.productIdStr)
      tracer = req.app.locals.tracer
    
      api.context.with(api.propagation.extract(api.ROOT_CONTEXT, req.headers),async () => {
        //---
       var returnedData=""
       span = {}
        Promise.all(
          [ function(){
            span = req.app.locals.tracer.startSpan('calculate-reviews', {
              kind: 1, // server
              attributes: { star_colour: starColor },    
            });
            let promise;
            api.context.with(api.setSpan(api.context.active(), span),async () => {
              additionalHeaders = {'Content-Type':'application/json'}
              function addHeader(value, index, array) {
                if (typeof req.headers[value] !== 'undefined' && req.headers[value] !== null){
                  additionalHeaders[value] = req.headers[value]} 
              }
              headersToPropogate.forEach(addHeader)
              api.propagation.inject(api.context.active(),additionalHeaders)
              requstPath='http://'+ratingsService +":"+ratingsServicePort + "/ratings/" + productId
              //GetRatings
              // Make HTTP Call to the ratings service here.
              promise = axios.get(
                requstPath,
               {headers:additionalHeaders}
              )
              .then((res) => {
                log_info(span,"Get Ratings give value")
                span.addEvent('Data available from ratings ');
                returnedData=res.data
              })
              .catch((error) => {
                log_info(span,"Get Ratings did not give value, Using default Values")
                span.addEvent('Data not available from ratings ');
                console.error(error)
              })
              .finally(() => {
                span.end();
              });
    
            })
            return promise;
          }()]
        )
        .then(() => {
          if (returnedData !== ""){
            
            res.writeHead(200, {'Content-type': 'application/json'})
            res.end(JSON.stringify(getJsonResponse(productId,returnedData.ratings.Reviewer1, returnedData.ratings.Reviewer1)))
          }
          else{
            res.writeHead(200, {'Content-type': 'application/json'})
            res.end(JSON.stringify(getJsonResponse(productId,starsReviewer1, starsReviewer1)))
          }
        })
        .catch((error) => {
          res.writeHead(200, {'Content-type': 'application/json'})
          res.end(JSON.stringify(getJsonResponse(productId,starsReviewer1, starsReviewer1)))
        })
        .finally(()=>{
          span.end()
        })
        
        })
      //---
    });

我面临的问题是，当我查看生成的痕迹时，它似乎是错误的：

问题是：

• “计算评论”跨度没有关闭
• 如何删除似乎自动添加的“HTTP GET”。我试图覆盖这是我的跟踪器设置，但它不起作用。node-express-reviews-service除了以下内容之外，似乎还创建了一个新的跨度HTTP GET：

registerInstrumentations({
    tracerProvider: provider,
    instrumentations: [
      // Express instrumentation expects HTTP layer to be instrumented
      new HttpInstrumentation({
        requestHook: (span, request) => {
          span.updateName("node-express-reviews-service")
        }
    }),
      new ExpressInstrumentation(),
    ],
  });

• HTTP 调用 rating.default 的跨度在调用之前开始和结束calculate-reviews。理想情况下，跨度ratings.default应该在之后开始calculate-review并在之前结束。但是在图像calcualte-reviews跨度开始和结束之后ratings.default。我做错了什么，正确的做法是什么？
• 我在“计算评论”下得到的错误“时钟偏差调整已禁用；未应用 -53.6005ms 的计算增量”是什么？

标签： javascriptnode.jsexpressopentracingopen-telemetry

Answer 1

我尝试重构代码以使其更具可读性和可理解性，希望这将是找出问题所在的良好起点。但实际上，我不明白这应该做什么，所以我无法真正调试它。

router.get('/:productIdStr', async (req, res) => {

    const starsReviewer1 = -1;
    const starsReviewer2 = -1;
    const productId = parseInt(req.params.productIdStr);
    const tracer = req.app.locals.tracer;

    await new Promise(resolve => api.context.with(api.propagation.extract(api.ROOT_CONTEXT, req.headers), resolve)); // Not sure what this does? It doesn't return anything?

    const span = req.app.locals.tracer.startSpan('calculate-reviews', {
        kind: 1, // server
        attributes: { star_colour: starColor },
    });

    await new Promise(resolve => api.context.with(api.setSpan(api.context.active(), span), resolve)); // Still not sure what this does, as it still doesn't return anything

    const additionalHeaders = { 'Content-Type': 'application/json' };

    headersToPropogate.forEach(value => { // headersToPropogate is undefined?
        if (typeof req.headers[value] !== 'undefined' && req.headers[value] !== null) {
            additionalHeaders[value] = req.headers[value]
        }
    });

    api.propagation.inject(api.context.active(), additionalHeaders); // No idea what this does, it doesn't seem to be asynchronous

    const requstPath = 'http://' + ratingsService + ":" + ratingsServicePort + "/ratings/" + productId;
    
    const returnedData = await axios.get(
        requstPath,
        { headers: additionalHeaders }
    ).data;

    if (returnedData !== "") {
        res.writeHead(200, { 'Content-type': 'application/json' })
        res.end(JSON.stringify(getJsonResponse(productId, returnedData.ratings.Reviewer1, returnedData.ratings.Reviewer1)))
    }
    else {
        res.writeHead(200, { 'Content-type': 'application/json' })
        res.end(JSON.stringify(getJsonResponse(productId, starsReviewer1, starsReviewer1)))
    }

    span.end(); // No idea what this is either
});