Synthetic monitor – counting api.fail() by message & custom error code

[deni]

Hi,

I have a Browser Synthetic monitor with a JavaScript step, where under certain conditions I explicitly fail the execution using:

api.fail("My message");

What I’m trying to achieve is:

• a metric that counts failures of the synthetic monitor,

• grouped or filtered by the failure message ("My message").

What I see so far

In Data Explorer, I can find synthetic error/failure metrics that allow split by:

• geolocation

• synthetic event

• error code

However, I don’t see any dimension related to the failure reason / message coming from api.fail().

My questions

1. Is it possible to create a metric that counts synthetic failures based on the custom message passed to api.fail()?
   (e.g. count executions failed with "My message")

2. Is there a way in a JavaScript step to explicitly define an error code when calling api.fail() (similar to HTTP error codes), or is it always message-only?

If this is not supported directly:

• what would be the recommended best practice for distinguishing different failure reasons inside a single synthetic monitor?

Thanks in advance for any guidance or examples!

Regards, Deni

[dannemca · Accepted solution]

I have done something similar but for http synthetic.

During the failure, in the javascript step (post execution in HTTP),  I call the metric api to ingest a data point with the error message as dimension.

https://docs.dynatrace.com/docs/discover-dynatrace/references/dynatrace-api/environment-api/metric-v... 

And for question 2, I don't think you can define custom HTTP errors to be displayed as your synthetic HTTP result.
https://docs.dynatrace.com/docs/observe/digital-experience/synthetic-monitoring/browser-monitors/bro... 

[dannemca]

Example of javascript code to call the metric api (it can be the log ingest api too)

(async function () {
  try {
    const ENV_URL   = 'https://<yourtenanthere>.live.dynatrace.com';
    const INGEST_URL = `${ENV_URL}/api/v2/metrics/ingest`;

    const API_TOKEN = '<yourtokenhere>';

    const metricKey = 'custom.synthetic.browser.message';
    const dimKey    = 'message';
    const dimValue  = 'Your Message';

    const gaugeValue = 1;                    
    const timestamp  = Date.now();           

    const line = `${metricKey},${dimKey}="${dimValue}" gauge,${gaugeValue} ${timestamp}`;

    const res = await fetch(INGEST_URL, {
      method: 'POST',
      headers: {
        'Authorization': `Api-Token ${API_TOKEN}`,   // requires metrics.ingest scope
        'Content-Type': 'text/plain; charset=utf-8'
      },
      body: line,
      mode: 'cors',
      cache: 'no-store'
    });

    const text = await res.text(); 

    api.info(`Metric ingest HTTP status: ${res.status} ${res.statusText}`);
    if (text) api.info(`Ingest response: ${text}`);

    if (res.status === 202 || res.status === 400) {
      api.finish();
    } else {
      api.fail(`Metric ingest failed: ${res.status} ${res.statusText}`);
    }
  } catch (err) {
    api.fail(`Metric ingest error: ${err.message}`);
  }
})();

Regards

[deni]

Thank you very much 🙂
I’ve just started to “fight” with this and I really appreciate the example you shared.

just one more question, currently my code on the javascript synthetic event is:

var text = document.documentElement.innerText;
var isFound = text.indexOf('text') > -1;

if (isFound) {
    api.fail("My reason");
}

How to integrate this call, something like this?

<my code>
(async function () { ... })

or should insert my code somewhere inside the async function?

Thank you!

Regards, Deni