New array format for input/output definition in hiera requires polluting configs

[sparr]

Inputs and outputs (and aggregators if I ever get a PR ready for that) that previously had no configuration no longer work.

cpu: was previously enough to create a cpu input. Now cpu: fails because telegraf.conf.erb:80 expects it to contain an array, and cpu: [] fails because the first element of that array is expected to be a hash. I find myself having to do some nonsense like this:

cpu:
  - placeholderkey: placeholdervalue

which of course ends up polluting my actual telegraf.conf with those placeholders.

If there's a better way to make this work with the new code from #80, I would love to know. If there's not, this seems severe enough to be a bug in need of fixing, and maybe fixing it would also address the minor annoyance of old configs not working with the new code; it would be nice if the code recognized a bare hash as functionally identical to an array containing one hash.

[sparr]

To say it another way... I cannot come up with a hiera yaml config that produces this telegraf.conf snippet:

[[inputs.cpu]]

[[inputs.mem]]

[nrdmn]

Please see the example form the readme. You can write

mem: [{}]

to get

[[inputs.mem]]

[sparr]

Was there some rationale for not supporting the old formats? There doesn't even seem to be any ambiguity.

[nrdmn]

According to the toml specification, the old format is not the correct yaml representation of telegraf's toml config.