Support specifying a timezone manually with strptime parser

[guilload]

For instance:

name: timestamp
type: datetime
description: Time at which the event was emitted
input_formats:
  - rfc3339
  - unix_timestamp
  - "%Y %m %d %H:%M:%S.%f %z"
  - strptime:
      format: "%Y %m %d %H:%M:%S.%f"
      default_timezone: America/New_York

[fulmicoton]

Maybe default_timezone?

[guilload]

default_timezone sounds better, indeed.

[rdettai]

I think we should raise an error during the parsing of the config if the user provides a format with a timezone and a default timezone (%z or %Z). It's better to fail early. Any opinion @fulmicoton ?

[rdettai]

Parsing a timezone like America/New_York and use it to compute a timestamp from a date string requires a TZ database. The most popular / better maintained one seems to be chrono-tz, but we use time almost everywhere in Quickwit (and Tantivy). There is a time-tz crate that would fit more nicely into the existing code, but it appears to be substantially less used.

[fulmicoton]

In #5248 I'm rewriting a tiny bit the code that parse dates. It will be possible to pass an utc offset which might simplify this issue. Getting the offset from the timezone will require a bit of work/wits however.

[guilload]

You may also have a look at https://github.com/quickwit-oss/quickwit/tree/guilload/strptime-timezone