Named capturing group to different names

user_3119050 0
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I'm working on a logging stack based on Banzai Cloud ClusterFlow, we've a log that is currently parsed with a regular expression and placed in a specific name; however we would like to deprecate that name and replace it with a new one, let's say the pattern is just like the following one:

^(?<someName>[^ ]*) (?<someNameWeWishToDeprecate>[^ ]*)$

supposing we receive a log line such as

prop1 prop2

it will produce two properties in our parsed log:

someName=prop1
someNameWeWishToDeprecate=prop2

What we would like to obtain is instead

someName=prop1
someNameWeWishToDeprecate=prop2
someNewFancyNae=prop2

As you can see we'd like to keep the old name but also have the new one; is this possible by elaborating the regular expression?

FYI: the regular expression engine is ruby-based

fluentd ruby regex
1 Answers

You can nest the named capturing groups and use

^(?<someName>[^ ]*) (?<someNewFancyNae>(?<someNameWeWishToDeprecate>[^ ]*))$

Or,

^(?<someName>\S+)\s+(?<someNewFancyNae>(?<someNameWeWishToDeprecate>\S+))$

See the regex demo.

enter image description here

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