Vector: Allow multiple log field type conversions

[arrrght]

May i use one fields in multiple transform?

[transforms.some.types]
  timestamp2 = "timestamp|%Y-%m-%d %H:%M:%S%.f"
  timestamp2 = "timestamp|%d.%m.%Y %H:%M:%S"

i.e. if first transform type failed then try next
now it just dropped if failed

[Jeffail]

Hey @arrrght, unfortunately it's not possible to have duplicate keys within the types table as it is invalid TOML. However, we could potentially expand the values to support arrays, where if a conversion fails then the next is attempted, and so on.

Perhaps something like this:

[transforms.some.types]
  timestamp = [
    "timestamp|%Y-%m-%d %H:%M:%S%.f",
    "timestamp|%d.%m.%Y %H:%M:%S"
  ]

We should also capture duplicate keys and report them to the user to make it clear they're being ignored.