added retrieve jaeger trace endpoint. (#147)

lib/utils/jaeger-utils.js

@@ -0,0 +1,18 @@
+const bent = require('bent');
+const getJSON = bent(process.env.JAEGER_BASE_URL || 'http://127.0.0.1', 'GET', 'json', 200);
+
+const getJaegerTrace = async(logger, traceId) => {
+  if (!process.env.JAEGER_BASE_URL) {
+    logger.debug('getJaegerTrace: jaeger integration not installed');
+    return null;
+  }
+  try {
+    return await getJSON(`/api/v3/traces/${traceId}`);
+  } catch (err) {
+    logger.error({err}, `getJaegerTrace: Error retrieving spans for traceId ${traceId}`);
+  }
+};
+
+module.exports = {
+  getJaegerTrace
+};