Getting numeric data from the item value string

[karlism]

Hello,

I'm having hard time figuring out the problem that I'm trying to solve.

The goal that I want to achieve is to monitor master and slave DNS servers to see if DNS zones on them are in sync. That can be easily done by monitoring zone SOA record and using net.dns.record item key as every time zone is updated it's serial number changes and it is easy to notice mismatch. I get items with string values like this from each DNS server:
"example.com SOA ns.example.com hostmaster.example.com 2016060600 300 120 2419200 7200"
So far so good.

Unfortunately trigger function documentation page says that "All functions return numeric values only. Comparison to strings is not supported" so I'm out of luck comparing values of these items directly.

What I would like to achieve is to extract numeric serial number value ("2016060600" in the example above) from the SOA record item string. Is it possible at all or should I give up and use external scripts to achieve my goal?

Thanks!

[DmitryL]

Hello karlism!

As i see, unfortunately there are no built in possibility to convert string to number, or extract numbers from strings in zabbix.
You can find Feature Request that should help in your case.

https://support.zabbix.com/browse/ZBXNEXT-1443

As for now i would recommend using external scripts. There are very common functions to solve your problem.

Best regards,
Dmitry

[sudo092]

I came here looking for an answer at one point and then found out that as of Zabbix 3.4 (I believe) you can use item preprocessing to convert string values to integers with regex. So I thought i'd share my experience with it.

I'll use an example of converting MySQL "Slave_io_running" string states to numeric metrics....

In the item preprocessing tab i used two steps to convert string values into integers using match and replace functionality like this...

Name Parameters Output

Regular expression (.*) \1:No=0:Yes=1:Connecting=2
Regular expression (No|Yes|Connecting)(?=.*:\1=(\d)) \2

[Chassepa]

Hello sudo092,

Your solution is absolutely brilliant.

[fjofes]

Personaly I used Javascript to convert my Zabbix string value to int in a preprocessing step : parseInt(value)

[MoT]

Name Parameters Output
Regular expression (.*) \1:No=0:Yes=1:Connecting=2
Regular expression (No|Yes|Connecting)(?=.*:\1=(\d)) \2

We do not see the split between value, let me correct

Name	Parameters	Output
Regular expression	(.*)	\1:No=0:Yes=1:Connecting=2
Regular expression	(No|Yes|Connecting)(?=.*:\1=(\d))	\2

Someone explained all of this here:

https://catonrug.blogspot.com/2019/01/convert-text-to-number-zabbix-preprocessing.html

Apart from that, I think that you can also use Custom on fail option to set a default value for unrecognised strings

as described here:

https://www.zabbix.com/documentation/current/manual/config/items/preprocessing

[zarkgnok]

On Zabbix 5.4 here.
I got it working by adding a single pre-processing step:
select 'Simple change' from the dropdown.
If you test it with the [test] button, you should see
your value succeeding the test, and
a footnote by Zabbix: "Result converted to Numeric (unsigned)"

HTH!

Michael

[zarkgnok]

Sorry, forget my earlier answer, it didn't output any data.

Notes: working on Zabbix 5.4 here.

I've got TWO preprocessing steps, and can confirm it's working now.
First preprocessing step:
(dropdown):'regular expression' left field: (.*) right field: \1

Second preprocessing step:
(dropdown) 'simple change' <no parameters possible>


It even seems to work just with the first preprocessing step.

HTH,
Michael

[DeeZ]

I do it with processing (Zabbix 6.0)

On item - processing - javascript

"return parseInt(value)"