fix(inputs.puppetagent): Update default summary path in puppetagent

[Mihitoko]

Summary

This fixes #19256.
Update the path to the new default to make it clear which file is meant.
I also added a hint to necessary puppet config adjustments to get the plugin to work correctly.

Checklist

• No AI generated code was used in this PR
• AI generated code used in this PR follows the InfluxData Policy on AI-Generated Code Contributions

Related issues

resolves #19256

[Mihitoko]

Note: the previous lint job failed and from the build output it tried to post a comment.
But Github returned 403, looks like something is wrong with the configured token.
https://github.com/influxdata/telegraf/actions/runs/29201933211/job/86674674958#step:4:175

[skartikey]

plugins/inputs/puppetagent/puppetagent.go:89-90 - the plugin still falls back to the old path (/var/lib/puppet/state/last_run_summary.yaml) when location is not set, so after this PR the documented example and the actual default behavior diverge: a user with a bare [[inputs.puppetagent]] section gets the old path while the docs show the new one. Please update the fallback in Init in this same PR to the same value the sample shows, and given that the official AIO packages default publicdir to /opt/puppetlabs/puppet/public (PUP-10627) and are how most Puppet 7/8 deployments are installed, I would make that shared value /opt/puppetlabs/puppet/public/last_run_summary.yaml (see item 2). Since this changes behavior the PR should then be retitled fix(inputs.puppetagent): .... The risk window is small: on any Puppet 7+ host the old fallback already fails with a stat error, and Puppet 6 is long EOL.

[skartikey]

the concrete example uses the distro-packaged flavor (/var/cache/puppet/public/...); per item 1 I would switch it to the AIO path /opt/puppetlabs/puppet/public/last_run_summary.yaml. The $publicdir parenthetical already covers users on other packagings; if desired, a single README prose line can mention the distro-packaged variant.

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_arm64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

☺️ This pull request doesn't significantly change the Telegraf binary size (less than 1%)

📦 Click here to get additional PR build artifacts

Artifact URLs

. DEB	. RPM	. TAR . GZ	. ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

[Mihitoko]

Hey 👋
Thanks for the fast review <3
I adjusted the pr according to your comments, please let me know if there is more to change

Also i decided to make the statement more generic by saying that $publicdir might be different rather then hard mentioning the path the debian package uses, because it really seems highly dependent on how the distro packages puppet.

[srebhan]

Thanks for your contribution @Mihitoko! Unfortunately, we cannot update the default location as we try do guarantee backward compatibility in Telegraf and your change would break everyone using a Puppet version before 7!

What I would like to see instead is a comment in the sample.conf file saying

  ## Location of puppet last run summary file
  ## Use the following path for puppet version 7+ ($publicdir/last_run_summary.yaml)
  ##   location = "/opt/puppetlabs/puppet/public/last_run_summary.yaml"
  # location = "/var/lib/puppet/state/last_run_summary.yaml"