And it does seem like people sometimes forget that CST is not the same thing as CDT. Several months ago (after the 2024 PST -> PDT crossover) I had someone across town tell me they wanted to set up a meeting at something like 9AM. But when the invite came, the time zone was set for 9AM PST instead of 9AM PDT. I assumed it was PDT since we were in the same locality. But I did make sure my schedule was clear for the hour before on the off chance they had some weird software bug that picked time zones at random.
If your point is something similar, then I heartily agree. In theory, converting between time-zones and daylight and standard times is easy, but in practice there are several situations where it's made more difficult than it should be.
- CST: Central Standard Time UTC−06
- CST: China Standard Time UTC+08
- CST: Cuba Standard Time UTC−05
But you bring up another good example. I've worked with people who write times as "PST" or "EST" all year long. This bothers me in its simple incorrectness -- I do know what they mean but I hate autocorrecting them.
But I've also worked with people in parts of Indiana, and Mexico. When they say "CST" at any time of the year, they might mean it precisely!
My strategy is to write, e.g. "8:30 AM US/Pacific". Which probably annoys other people, but at least it's precise and unambiguous. I think it's less awkward than the equivalent "America/Los_Angeles".
Full list of US lower 48 timezones: US/Arizona, US/Central, US/East-Indiana, US/Eastern, US/Indiana-Starke, US/Michigan, US/Mountain, US/Pacific.
And the +2s: US/Alaska, US/Aleutian, US/Hawaii
$ TZ=Asia/Shanghai python -c "import datetime; print(datetime.datetime.strptime('4CST', '%H%Z').astimezone(datetime.timezone.utc))"
1899-12-31 19:54:17+00:00
$ TZ=America/Chicago python -c "import datetime; print(datetime.datetime.strptime('4CST', '%H%Z').astimezone(datetime.timezone.utc))"
1900-01-01 10:00:00+00:00
$ TZ=America/Havana python -c "import datetime; print(datetime.datetime.strptime('4CST', '%H%Z').astimezone(datetime.timezone.utc))"
1900-01-01 09:29:36+00:00
$ TZ=America/Havana python -c "import datetime; print(datetime.datetime.strptime('4CDT', '%H%Z').astimezone(datetime.timezone.utc))"
1900-01-01 09:29:36+00:00
$ TZ=America/Los_Angeles python -c "import datetime; print(datetime.datetime.strptime('4CST', '%H%Z').astimezone(datetime.timezone.utc))"
ValueError: time data '4CST' does not match format '%H%Z'
That last error was real fun to debug when something worked in production but not locally.
As a nearby comment indicates, it's not clear any browser makes use of it.
All times on the page are in UTC and are wrapped in a <time> element. The raw UTC time is on the datetime attribute and a fallback more easily readable time is inside the tags. Some JS on the page removes whatever text is inside the tag and replaces it with the user's locale specific format (no libraries required, it's a part of the browser standards).
User friendly times wasn't actually the reason we implemented it.
Our largest concern was our E2E testing. We needed to make sure that the dates/times displayed were always right (and since subscriptions involve money, we wanted to make sure that part of the website was the most tested.) The E2E testing simply ignores whatever is inside the tag and reads the datetime attribute instead. Then we can fastforward or rewind the simulated time inside the test to make sure everything is working as expected.
My solution to inconsistent time rendering in AWS (sometimes UTC, sometimes localtime) is to run a separate browser profile for AWS (and third party status pages) that that's always running in UTC.
But seriously, status page people: there's no excuse for being vague about timezones!
Rhetorical question (I know why, humans manually involved, incentive to not report SLA breakage, etc.): How does their status page not auto-update when one of their core APIs goes to basically 99% 500 (or even above 5% 500) status error?
For once I can feel mild pleasure at seeing the tables turned…
To be honest I don’t know why all my projects are always in USE1, I guess it’s just because that’s where we have always had them for my lab so I’ve stuck with it for no good reason…
the API whcih sits behind ELB is working fine
edit: us-east-2
I guess I'll increase the frequency of some probes to get better aligned with the official timeline :)