BaseWSGIServer: throw exception on bind failure rather than calling sys.exit() about werkzeug HOT 4 CLOSED

Why can't you catch SystemExit?

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I can and did once in finally figured out why I could not catch the exception. My concern is that the behavior is surprising, undocumented, and difficult to diagnose. Unless you know that SystemExit specificially is the exception being raised, your attempts to catch it will likely fail. In the interests of not frustrating users of Werkzeug it would be better to replace:

sys.exit(1)

With:

raise

If this is undesirable for some reasons, this unusual behavior of run_simple() should at least be documented. And that brings us to another problem. While run_simple() is described in the tutorial, I can't find it anywhere in the reference section. Maybe I'm missing it, but I can't find it even with the search function.

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The development server isn't really intended for embedding. You can, but it's not particularly secure (nor is http.server which it wraps). Both have strong warnings about this in their docs, and the dev server shows a warning when started as well. The development server is intended for local development only. You should use a production server, such as Waitress, when embedding. For local development, the fact that the server exits when it can't connect seems fine.

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OK. As you say, there is a workaround, even if it is obscure. I was feeling pretty frustrated when I wrote this bug report. And since the primary application is testing, the error message is adequate and many users would consider a stack trace worse.

I still do think though that run_simple() and other public interfaces in werkzeug.serving should be included in the reference documentation.

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