`http.server`: Update default `extensions_map` to include `.wasm`

[vadimkantorov]

Then python -m http.server is suitable for experimenting with WASM/Emscripten projects. Currently people need to roll their own scripts like https://github.com/python/cpython/blob/main/Tools/wasm/wasm_webserver.py

Here are the default extensions_map (btw could include text/html, text/javascript, text/xml, text/json or other popular extensions for debugging very simple static web app projects):

cpython/Lib/http/server.py

Lines 661 to 666 in a1a3193

	extensions_map = _encodings_map_default = {
	'.gz': 'application/gzip',
	'.Z': 'application/octet-stream',
	'.bz2': 'application/x-bzip2',
	'.xz': 'application/x-xz',
	}

Adding MIME for .data by default is also nice for this is a file extension of Emscripten file system data packages.

It would also be nice if the default http server can be made multi-threaded, because in some rare circumstances it can block Emscripten data package loading. I rolled my own server https://gist.github.com/vadimkantorov/a8c3aca556824df061e84b1d10edee44 which also was serving ETag / HTTP 304 properly.

At least it would be nice to support customizing extensions_map in http.server command line, so that one can call python -m http.server --map-mime .wasm:application/wasm --map-mime .data:application/octet-stream --serve-permanent-etag

Linked PRs

• gh-106900: Add .wasm files to extensions_map in SimpleHTTPRequestHandler #130430

[brettcannon]

I personally don't have an issue with adding .wasm, but I'm not sure about .data as that's extremely generic.

[vadimkantorov]

Yeah, I tend to agree about .data by default, but allowing the user to extend override/extend this list very simply via a few command-line options would be nice!

Some other two feature requests I'm proposing for the builtin python -m http.server (maybe via command-line switches as well):

• check if it follows etags / allow to force browser caching (useful for debugging browser caching, e.g. Chrome won't cache anything larger than ~50mb which is a problem for large .wasm files for instance)
• allow to serve with multi-threading (otherwise sometimes Chrome hangs rendering in some rare situations) - e.g. allow serving with http.server.ThreadingHTTPServer instead of http.server.HTTPServer

I agree about .data - probably Emscripten should have used some existing format like .tar for these data packages

[brettcannon]

Some other two feature requests I'm proposing for the builtin python -m http.server

Those should be separate feature requests.

[vadimkantorov]

Sounds good! I'll check the existing source code of http.server and if still needed will factor out these two other feature requests in separate issues.

Let's keep in this issue the discussion about proposal of also adding a command-line option for extending/overriding other MIME types like python -m http.server --map-mime .wasm:application/wasm --map-mime .data:application/octet-stream (or some similar command line syntax)?

[brettcannon]

Let's keep in this issue the discussion about proposal of also adding a command-line option for extending/overriding other MIME types like python -m http.server --map-mime .wasm:application/wasm --map-mime .data:application/octet-stream (or some similar command line syntax)?

That's a separate request than adding .wasm to the default content-type mapping, so it should be a separate issue.

[donBarbos]

Looks like a good idea with no follow up so I'm going to send a PR