If you want it only temporarily for debugging purposes, or permanently
for all scripts in your system, it's not really feasible.
Hmm, I'm not sure that I like the idea of overriding the default logging level being set system-wide, or that there would be an especially strong use case for it. Instead, it seems more practically common to want to set it on an individual run of a program temporarily. In such cases, using some form of command-line parsing utility is a perfectly a viable option.
Well I meant more like a permanent "debug" mode, but the temporary case is probably the one more appealing to me and other users.
We have debugging flags for warnings, faulthandlers, asyncio etc... Arguably though, the easier it is to implement on your own, the less of a need there is to be an environment variable to do it. Also, I think the logging configuration should be on a per-program basis, rather than globally (which is what env vars are typically used for).
I agree that logging configuration should be on a per program basis. Maybe a flag should be the solution, like '-Linfo'.
When I said 'trivial', I didn't mean easy to implement. I meant that it's a much more common use case, and makes sense to have. -Wdefault is trivial to implement. Asyncio.debug is a single flag. Logging takes the same amount of lines, even more if you need to parse the args, but is much more common and needed. I've done a little stack overflow search, and there are tons of questions about having or creating such a feature manually.
Last but not least: our suggested methodology for libraries is to use "NullHandler". If a library uses it, errors will not show up unless you set up a handler (with probably stdout for debug) on the root logger. If '-Linfo' or '-x logging' will be part of the possible debug cmdline options, these obscure bugs would be much easier to track. (I personally spent a few days to track one like that not long ago)