Allow disabling rich using environment variable.

[racinmat]

Currently, the https://www.structlog.org/en/stable/console-output.html does not allow disabling rectangular stack traces in rich is installed.
Unfortunately, some libraries, e.g. tadata-org/fastapi_mcp#225 have rich as direct dependency, and there is no reasonable way how to uninstall it. For these cases, having environment variable to disable the behavior would be useful.
Other libraries using rich optionally provide this, e.g.

• typer allows disabling it by setting _TYPER_STANDARD_TRACEBACK=1.
• fastmcp allows disabling it by setting FASTMCP_ENABLE_RICH_TRACEBACKS=0.

[hynek]

Hm, those are rather different types of packages though.

The assumption of structlog is that it is controlled by the user of the library, not the enduser of the application (that ideally shouldn't know structlog exists in the first place).

I realize that with the support of NO_COLOR, I've already dipped my toes here, but there's a bunch of edge cases, especially if you do configure it and suddenly STRUCTLOG_NO_RICH=1 stops working.

---

But I'm aware that the whole console complex needs better ergonomics, tho.

I'm currently thinking of exposing the default console logger instance within dev and adding ways to change it (as distasteful as I find it).

So, if you could do something like

structlog.dev.default_logger.tracebacks = (
    plain_tracebacks if os.environ("YOUR_APP_PLAIN_TRACEBACKS", "0") == "1"
    else rich_tracebacks`
)

would that help you?

[racinmat]

Yes, that would help.

[hynek]

I have started working on this in #749 and I hope to have something useful before 25.5.