Search code examples
regexrubykubernetesfluentd

How to exclude pattern in <match> for fluentd config?

I want to output all in null, except the one pattern in match. I know there are some ways to do that via @labels for example, but i exactly want to exclude pattern in match.

I want to do like this:

<match {all tags except **events**}>

What i did:

I know i can use Ruby expressions in match like this:

<match #{tag.match(/^.*event.*$/) ? "fake_tag" : "**"}>
  @type null
</match>

Logic: "If current tag has pattern - set fake_tag for skip this match, else set ** for output all in null"

But this expression doesn't work because there is no variable $tag in ENV. As i understood Ruby expression can't use config variables like ${tag}.

Maybe i can set ENV variable before match step?

Like this:

<filter **event**>
  #{ENV["FLUENTD_TAG"] = ${tag}}
</filter>

<match #{FLUENTD_TAG.match(/^.*event.*$/) ? "fake_tag" : "**"}>
  @type null
</match>

These are my thoughts but maybe there are simpler ways.

The question is - how to exclude pattern in match ? :-)

Solution

  • Drop one, leave everything else:

    <match what.you.want.to.drop>
  @type null
</match>
<match **>
  # process everything else
</match>

    Drop everything except one:

    <match what.you.want.to.stay>
  # process here or send to a label
</match>
<match **> # Optional block. It will be dropped anyways if no other matches, but with a warning printed to a fluentd log.
  # Drop everything else explicitly to avoid warning.
  @type null
</match>