packaging: switch to YAML config files by default

[patrick-stephens]

Resolves #9714 by switching to using YAML configuration by default for all packages and containers.

For containers we should prepare a PR for the helm chart as well but it will not break the helm chart as that explicitly uses a .conf file for now.

We should ensure this is properly notified during the release notes and beforehand for folks to do any required updates to their rollouts.

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Testing
Before we can approve your change; please submit the following in a comment:

• Example configuration file for the change
• Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature
  installation: switch to YAML config files by default fluent-bit-docs#1551

Backporting

• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[patrick-stephens]

cc @stevehipwell on the helm side - the current chart uses a legacy config by default so should not be impacted by this change but maybe we should change the defaults there too?

• https://github.com/fluent/helm-charts/blob/79a39754f24bfd8f9396ddf207b41b48597999cb/charts/fluent-bit/values.yaml#L376
• https://github.com/fluent/helm-charts/blob/79a39754f24bfd8f9396ddf207b41b48597999cb/charts/fluent-bit/values.yaml#L494

[stevehipwell]

@patrick-stephens is the YAML support now idiomatic? I saw flush: 1 when I just gave this a quick scan.

[patrick-stephens]

@patrick-stephens is the YAML support now idiomatic? I saw flush: 1 when I just gave this a quick scan.

There's no change to syntax here, this is primarily around the default config file we're using.

[stevehipwell]

So in the context of Kubernetes I think the current "YAML" format is problematic given the fact that it's not idiomatic YAML but is called YAML and looks like YAML. That said am I correct in understanding that some capabilities are only available via the YAML config?