Opentelemetry with search additions example

telemetry.js

const Utils = require('./utils');
const Index = require('../search/index');

const FILTERS = ['your','filter','fields','here'];

const Telemetry = {

  // Middleware to start a span before the route controller
  start : function(req, res, next) {
    if(req && !req.span) {
      req.startTime = process.hrtime(); // Capture start time
      let span = {
        'trace_id' : Utils.generateUniqueId(16),
        'span_id' : Utils.generateUniqueId(8),
        'http.method': req.method,
        'http.url': req.originalUrl,
        'http.target': req.url,
        'http.host': req.headers.host,
        'http.scheme': req.protocol,
        'http.user_agent': req.headers['user-agent'],
        'http.route': req.route ? req.route.path : '',
        'timestamp': new Date().toISOString(),
      }
      req.span = span;
    } 
    next();
  },

  // Middleware to end the span and log it to OpenSearch after the route controller
  end : function(req, res, next) {
    let span = req.span;
    if (span) {

      res.on('finish',()=>{

        const tookTime = process.hrtime(req.startTime);
        span.took = parseInt((tookTime[0] * 1000) + (tookTime[1] / 1000000)); // Convert to milliseconds

        span['http.status_code'] = res.statusCode
        span['http.response_content_length'] = res.get('content-length') || 0;
        span['http.flavor'] = `HTTP/${req.httpVersion}`;

        if(req.user && typeof req.user =='object') {
          span.organizationid = req.user.organizationid;
          span.userid = req.user.id;
        }

        if(req.params && req.params.id) {
          span.resourceid = req.params.id;
        }

        if(req.query) {
          //Search Query
          ['query','page'].forEach(k=>{
            if(req.query[k]) span[k] = req.query[k];
          });
          let filter = {};
          FILTERS.forEach(k=>{
            if(req.query[k]) filter[k] = req.query[k];
          });
          if (filter) span.filter = JSON.stringify(filter);
        }

        if(res.hits) {
          //Search Results
          let ids = [];
          res.hits.forEach((h)=>{
            if(h&&h.inner_hits&&h.inner_hits.sections.hits.hits){
              h.inner_hits.sections.hits.hits.forEach(ih=>{
                ids.push(
                  JSON.stringify({"d":h._source.id,"s":ih._source.id})
                );
              });
            } else {
              ids.push(JSON.stringify({"d":h._source.id}));
            }
          })
          if(ids.length) span.results=ids;
          //console.log(span.results);
        }

        Index.index_log(span);
      })
    }
    //Some routes don't have a 'next'
    if(next) next();
  }
}

module.exports = Telemetry;

Apache 2.0 License :)