Google GCP Trace: Trace with nested user functions information - google-app-engine

Question

Currently this is the picture I have when analysing GCP trace. It is useful but we need to have a deeper analysis on some spots we want to improve.
What we would like to do is to have something like this
| vi/route/r
| function abc (75 ms)
| redis-hget (1 ms)
| datastore (69 ms)
| function cde (30 ms)
| ...
We have tried a lot but we didn't find further documentation regarding the concepts of GCP trace, rather only detailed API calls.
Here is our POC
Entry Level
require('#google-cloud/trace-agent').start({
projectId: 'my-project',
keyFilename: './my-credentials.json',
stackTraceLimit: 0,
});
const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const toSecondLevel = require('./controllers/home');
const initController = require('./controllers/init');
app.post('/poc/', bodyParser.json(), async (req, res) => {
const trace = require('#google-cloud/trace-agent').get()
const rootSpan = trace.getCurrentRootSpan();
const { requestType } = req.body;
rootSpan.addLabel('Root - First Level' , requestType);
await toSecondLevel(rootSpan, req, res);
rootSpan.endSpan(new Date());
res.send('Hello World! ===> ' + requestType);
});
app.listen(3000, function () {
console.log('Example app listening on port 3000!');
});
Second Level
const toThirdLevel = require('../services/home')
const secondLevelFunction = async (rootSpan, req, res) => {
await secondLevelFunctionPromise(rootSpan);
}
const secondLevelFunctionPromise = (rootSpan) => new Promise((resolve, reject) => {
const span = rootSpan.createChildSpan({ name: 'secondLevelFunction' });
setTimeout(async () => {
console.log('secondLevelFunction', span.getTraceContext())
span.addLabel('Should be nested to Root?', 'NOT nested');
await toThirdLevel(rootSpan, new Date());
span.endSpan(new Date())
resolve();
}, 2400);
})
module.exports = secondLevelFunction;
And the third Level
const thirdLevelFunction = (rootSpan, parametro1) => new Promise((resolve, reject) => {
const span = rootSpan.createChildSpan({ name: 'thirdLevelFunction' });
setTimeout(() => {
span.addLabel('thirdLevelFunction', 'not nested as well')
console.log(span.getTraceContext())
span.endSpan(new Date());
resolve();
}, 1392);
})
module.exports = thirdLevelFunction;
The problems / Conceptual questions:
1- No Span is Nested in the POC
2- All the Spans has getTraceContext(). Can I use this to some how nest my Spans?
3- Is it possible to make what I am intending to do? (A- Nest my Span and B- Nest into the same tree showed in the first image?
4- Class RootSpan extends Span. But I can't have any different behaviour from this.

Answer 1

Now it is working. What is needed (typescript to better understanding):
import * as traceAgent from '#google-cloud/trace-agent';
const trace: traceAgent.PluginTypes.Tracer = traceAgent.get();
const span: TraceSpan = this.trace.createChildSpan(options);
...
span.addLabel('property',yourContent);
spam.endSpan(getDate());
Important to notice that traceAgent.get() is a factory and the plugin manages to give it coherence on the order of events even if several threads are asking for new spans.
I highly recommend:
use the interfaces provided as the documentation is poor. Reading
the interfaces and actual code give you better understanding
Make a Wrapper to your span so you can create an indirection much more tied
to your needs. Now I can open a span with a label, close with a
label, add an object so the I can create a label based on the
object.