Wasm build instructions are confusing to this wasm newbie

[smontanaro]

Documentation

I know nothing about wasm or emscripten, but am curious. I know next-to-nothing (anymore) about Docker. So, naively working my way through Tools/wasm/README.md I see:

docker run --rm -ti -v $(pwd):/python-wasm/cpython quay.io/tiran/cpythonbuild:emsdk3

followed immediately by

mkdir -p builddir/build
pushd builddir/build
../../configure -C
make -j$(nproc)
popd

The docker run command puts me in a docker shell, from which the configure command is pretty worthless. It seems I am supposed to be back at my computer's prompt, but what good is the docker run command at that point? Am I supposed to check out .../python/cpython inside the docker env? I'm clearly missing something and suspect other people new to wasm probably are as well.

[erlend-aasland]

• The docker command should be executed from your local CPython repo clone (pwd == CPython repo).
• ../../configure -C should be ../../cpython/configure -C

The docker run command puts me in a docker shell, from which the configure command is pretty worthless. It seems I am supposed to be back at my computer's prompt, but what good is the docker run command at that point?

No, it is not worthless; the -v option to docker run maps $(pwd) to /python-wasm/cpython inside the Docker container. You're supposed to run configure and make from within the container.

Am I supposed to check out .../python/cpython inside the docker env

No need. It is already mapped via the -v option.

[smontanaro]

Thanks. the incorrect configure reference was the problem. make is now making.

[tiran]

The documentation assumes that you run all commands from a CPython checkout inside and outside the container. Depending on how you run the container, you may /python-wasm as working directory. You need to run the commands from /python-wasm/cpython -- or better use the shell scripts in /python-wasm.

[smontanaro]

Latest changes worked for me until I got here:

emrun builddir/emscripten-browser/python.html

This failed from inside the running Docker image with this error:

Unable to find browser "firefox"! Check the correctness of the passed --browser=xxx parameter!

I don't know where browser firefox is specified. Must be a default.

The second option (running wasm_webserver.py) worked for me outside the running image. Assuming it's less picky about available web browsers, maybe it should be the first option.

[erlend-aasland]

How's the last changes working out for you, Skip?