topic Re: Calculated service metrics to capture request name containing regex in Open Q&A

Calculated service metrics to capture request name containing regex

Fisher — Tue, 07 Feb 2023 10:58:32 GMT

Hello, team!

I try to create a calculated service metric. It must capture request like: /projects/{projectId}/files/**

For example: projects/platform_features/files/help/

When I create a metric, I use the condition "request name contains regex /project\/.*\/files/.*[a-zA-Z0-9]" - this condition doesn't work, because in metric there is "no data", but I see these requests in MDA.

I tried to use another regex: /project/[a-zA-Z0-9]*/files/.*[a-zA-Z0-9] - but Dynatrace show me the message "Greedy or lazy character classes are not allowed, please use a possessive quantifier instead."

And I tried the third variant: /project/[a-zA-Z0-9]/files/.*[a-zA-Z0-9] - Dynatrace doesn't show me an error, but when I try check this regex in regex101.com - it's an "invalid expression".

Could you help me?

Re: Dynatrace regex question

MichalOlszewski — Tue, 07 Feb 2023 05:38:07 GMT

Hi @Fisher,

2 things with Your regexes -

1st You forgetting to escape special char "/" which should always be "\/" - even thou some engines accept unescaped "/" is highly recommended to do so. Every one You posted here have this issue in one or more places
2nd don't use .*[set] as way out of greedy/lazy/possessive as it won't work and will cause mess.

I Believe You were looking for:

\/project\/[a-zA-Z0-9]++\/files\/[a-zA-Z0-9]++

Small tip for future with regexes 🙂

+,* is greedy - takes as much as possible - You don't want that (mostly)
++, *+ is possessive - takes as much as needed - You usually want that (with rules and filtering)
+?, *? is lazy - takes as few as needed - You might want that (with capturing)

Re: Dynatrace regex question

Fisher — Tue, 07 Feb 2023 09:46:09 GMT

Thank you, Michal.

But it doesn't work(

I still can't see data in this calculated metric

Re: Calculated service metrics to capture request name containing regex

Romanenkov_Al3x — Tue, 07 Feb 2023 11:09:45 GMT

Hello from Nightmare...

\/projects\/(?>[a-zA-Z0-9-_]++)\/files\/(?>[a-zA-Z0-9-_]++)\/

Regards,

Romanenkov Alex

Re: Calculated service metrics to capture request name containing regex

Fisher — Tue, 07 Feb 2023 12:05:16 GMT

@Romanenkov_Al3x

@MichalOlszewski

Colleagues, thanks for help!

But trouble was so easy - I missed letter "s" in word project

I'm sorry!

Re: Calculated service metrics to capture request name containing regex

Ana_Kuzmenchuk — Tue, 07 Feb 2023 14:04:09 GMT

Hi @Fisher thank you for sharing what the solution happened to be! Even though it was a typo, it started a discussion that I think many people will find useful!