parse_timestamp_from_date requires GNU coreutils' date

[Mina Galić]

running tests on FreeBSD, here's the output from "test_parse_unexpected_timestamp_format_with_date_command"

======================================================================
ERROR: test_dump.TestParseTimestamp.test_parse_unexpected_timestamp_format_with_date_command
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/home/freebsd/src/cloud-init/cloudinit/analyze/tests/test_dump.py", line 57, in test_parse_unexpected_timestamp_format_with_date_command
    float(dt.strftime('%s.%f')), parse_timestamp(new_stamp))
  File "/usr/home/freebsd/src/cloud-init/cloudinit/analyze/dump.py", line 48, in parse_timestamp
    timestamp = parse_timestamp_from_date(timestampstr)
  File "/usr/home/freebsd/src/cloud-init/cloudinit/analyze/dump.py", line 54, in parse_timestamp_from_date
    out, _ = util.subp(['date', '+%s.%3N', '-d', timestampstr])
  File "/usr/home/freebsd/src/cloud-init/cloudinit/tests/helpers.py", line 182, in _fake_subp
    return _real_subp(*args, **kwargs)
  File "/usr/home/freebsd/src/cloud-init/cloudinit/util.py", line 2079, in subp
    cmd=args)
cloudinit.util.ProcessExecutionError: Unexpected error while running command.
Command: ['date', '+%s.%3N', '-d', '17:15 08/08']
Exit code: 1
Reason: -
Stdout:
Stderr: date: illegal time format
        usage: date [-jnRu] [-d dst] [-r seconds|file] [-t west] [-v[+|-]val[ymwdHMS]]
                    [-I[date | hours | minutes | seconds]]
                    [-f fmt date | [[[[[cc]yy]mm]dd]HH]MM[.ss]] [+format]
-------------------- >> begin captured logging << --------------------
cloudinit.util: DEBUG: Running command ['date', '+%s.%3N', '-d', '17:15 08/08'] with allowed return codes [0] (shell=False, capture=True)
--------------------- >> end captured logging << ---------------------

BSD date cannot parse arbitrary input, it will only parse input based on an input format.
Additionally, the `-d` flag *sets* the date on BSD.

[Scott Moser (smoser)]

I think the right fix on this is to drop the 'date' usage entirely.
Just support a reasonable set of formats and blow up with a good error that says what it tried to parse.

[Mina Galić (minagalic)]

extremely 👍

[Paride Legovini (paride)]

I think Scott's suggestion is sensible. The dateparser python module is able to parse free format human readable date strings, mostly like GNU `date -d <date>`, but we probably don't need it.

[Mina Galić (minagalic)]

I think this code has moved, or been removed in the unit test refactoring

[James Falcon (falcojr)]

Looks like this was fixed way back in https://github.com/canonical/cloud-init/commit/a8dcad9ac62bb1d2a4f7489960395bad6cac9382 .

It now lives at https://github.com/canonical/cloud-init/blob/main/tests/unittests/analyze/test_dump.py

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3502