How to display 100% degradation in SLO?

[vvasudev]

Hi,

I'm new to Dynatrace and I'm currently working on setting up monitoring in non production environment that will eventually move to production. Currently, I'm trying to create a SLO for a span that we intentionally ran to have a failure rate of 100%. However, the SLO is not able to evaluate it.

DQL that I'm using:

fetch spans
| filter matchesValue(endpoint.name, "<endpoint_name>") AND matchesValue(entityAttr(dt.entity.process_group, "tags"), "*APISECCluster*") 
| fields start_time, end_time, Tier, span.name, duration, span.status_code, endpoint.name
| makeTimeseries {
    EPM = countIf(span.status_code == "error", default: 0),
    CPM = count(default: 0)
  }, by: { API=endpoint.name }
| fieldsAdd sli=(((CPM[]-EPM[])/CPM[])*(100))
| fieldsAdd API

 Since its a 100% failure rate - sli=(((CPM[]-EPM[])/CPM[])*(100)) will be 0%, which is not being displayed correctly and not being reported in the 'Problems' app in DT. Is there a way to handle this scenario where 100% degradation (which resoluts in 0% sli) will be recognized by DT? Thanks in advance!

[Michal_Gebacki]

Hi, @vvasudev!

Is this documentation page helping to resolve challenge you've described above: add a service-level objective (SLO) tile to a dashboard?

Please let us know, thank you in advance!

[t_pawlak]

Hi,
You’re running into two things at once: DQL behavior and SLO evaluation rules.
Try this DQL so the SLI is always a valid number (no division-by-zero edge cases):

fetch spans
| filter matchesValue(endpoint.name, "<endpoint_name>")
| makeTimeseries {
    EPM = countIf(span.status_code == "error"),
    CPM = count()
  }, by: { API = endpoint.name }
| fieldsAdd sli = if(CPM[] > 0,
                     then: ((CPM[] - EPM[]) / CPM[] * 100),
                     else: 0)

In the SLO configuration, enable the option that allows evaluation when SLI = 0% (wording like “evaluate SLO even if SLI equals 0%” / “don’t suppress zero-value SLI”).

Once that’s set, a 100% failure rate → SLI = 0% will be treated as a valid SLO breach and will show up in Problems.