feat(plugins): Allow to override log-level per plugin

[srebhan]

Summary

This PR allows to override the Telegraf-wide log-level on a per plugin basis allowing to e.g. debug a certain plugin without being spammed by debug messages of other plugins.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #6584

[powersj]

This does not appear to work as I thought it would. For example, with this config I would expect to see debug messages from sarama:

[agent]
  debug = false
  omit_hostname = true

[[inputs.kafka_consumer]]
  log_level = "debug"
  brokers = ["localhost:9092"]
  topics = ["telegraf"]

It is not until I set the agent level debug to true do those messages appear.

Another example, where I would expect to see only info messages, but I see debug message about what server is in use for the test:

[agent]
  omit_hostname = true
  debug = true

[[inputs.internet_speed]]
  log_level = "info"
  interval = "1m"

[[outputs.file]]

[srebhan]

@powersj thanks for the thorough testing! It seems like during git rebase some of the model-config settings were lost and only the output model got the actually configured log-level. Pushed an update...

[telegraf-tiger]

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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

[powersj]

Much better!

We may need to do a follow up with the sarama logging for example. It looks to only respect the agent level debug value and I think that is how the logic is set up right now, but this gets us plugin specific log levels!

[srebhan]

@powersj solved the sarama issues in the course of #15695...