Force count to return 0 instead of "no results"

Fluxlang
1

Hello,

Sharing my solution to a problem I spent hours searching the internet for.

My use case - I want to alert on a count of something. If all is ok, the query returns “no results”. In fact, there is no data after the range statement, so this solution doesn’t work:

Because monitor.check sees “no results” instead of 0, I never get an “ok” status written to _monitoring and because my notifications are set to stateChanges, I never get a notification; there is no ok → warn or ok → crit change.

Here is the sudo code that doesn’t work:

import "influxdata/influxdb/monitor"
data = {_check_id: "0000....etc"}
from(bucket: "somebucket")
  |> range(start: -2h)
  |> filter(fn: (r) => r["_measurement"] == "some_measurement")
... if all is ok, there is already "no results" here
... a bunch more flux 
  |> count() 
  |> monitor.check:
    ok: (r) => r._value < 1
    warn: (r) => r._value >= 1,
    crit: (r) => r._value >= 10,
    messageFn: (r) =>
      if r._level == "crit" then
                "some crit message"
            else if r._level == "warn" then
                "some warn message"
            else
                "ok",
        data: data,
    )

Here is the sudo code that does work:

import "influxdata/influxdb/monitor"
import "csv"

data = {_check_id: "0000....etc"}
csvData =
"
_value
0
"

mydata = from(bucket: "somebucket")
  |> range(start: -2h)
  |> filter(fn: (r) => r["_measurement"] == "some_measurement")
... a bunch of flux 
  |> count() 

dummy = csv.from(csv: csvData, mode: "raw")
  |> map(fn: (r) => ({r with _value: int(v: r._value)}))

union(tables:[mydata,dummy])
  //get the highest value, either 0 from dummy or actual count from mydata
  |> max()
  // add _measurement or monitor.check fails
  |> set(key: "_measurement", value: "some_measurement")
  // add _measurement to group key or monitor.check fails
  |> group(columns: ["_measurement"])
  |> monitor.check:
    ok: (r) => r._value < 1
    warn: (r) => r._value >= 1,
    crit: (r) => r._value >= 10,
    messageFn: (r) =>
      if r._level == "crit" then
                "some crit message"
            else if r._level == "warn" then
                "some warn message"
            else
                "ok",
        data: data,
    )

Maybe this will help someone else!
Thanks,
Tom

2 Likes
2

@thopewell,
Thanks for sharing!!! Solution above