problem with regexp and converter string to float conversion

[mikkoss]

Relevant telegraf.conf:

[[processors.regex]]
 [[processors.regex.fields]]
    key = "DataReductionRatio"
    pattern = "^([0-9]+(?:\\.[0-9]+)?):(\\d)"
    replacement = "${1}"
    result_key = "DataReductionRatio-float"

 [[processors.regex.fields]]
    key = "DeduplicationRatio"
    pattern = "^([0-9]+(?:\\.[0-9]+)?):(\\d)"
    replacement = "${1}"
    result_key = "DeduplicationRatio-float"

 [[processors.regex.fields]]
    key = "CompressionRatio"
    pattern = "^([0-9]+(?:\\.[0-9]+)?):(\\d)"
    replacement = "${1}"
    result_key = "CompressionRatio-float"

[[processors.converter]]
 [processors.converter.fields]
  float = ["DataReductionRatio-float", "DeduplicationRatio-float", "CompressionRatio-float"]

System info:

telegraf-1.14.5-1 and later tested
Rhel 8 OS

Docker

Steps to reproduce:

hi,

I have an odd problem with regexp and converter in telegraf. I am getting an string reply from SNMP which I want to convert to float in a new result_key.

Data the snmp get's is for example:
DataReductionRatio: 1.935:1

which I want to save to a new field: DataReductionRatio-float
I have following regexp and converter configured in main telegraf.conf and then snmp collectors are in their own files in conf.d directory.

Expected behavior:

First string is cut with regexp to remove the ":1" part of the reply, then it's converted from string to float and saved to new result_key in influxdb.

Actual behavior:

This works now and then randomly when I restart thre telegraf agent, but now and then I do get errors:

[outputs.influxdb] When writing to [http://127.0.0.1:8086]: received error partial write: field type conflict: input field "DataReductionRatio-float" on measurement "hw_storagepool" is type string, already exists as type float dropped=1; discarding points

Is there some order that have to be specified to have this work every time? or is this a bug?

Additional info:

Attached picture of grafana graph.

[mikkoss]

Hi,

Very likely do to this: #8016
After adding order = 1 to [[processors.regex]] and order = 2 to
[[processors.converter]], I and after few restarts collection still works.

[ssoroka]

mikkoss is correct, the processor plugin order is non-deterministic without the order = n attribute