Building from sources¶
Building is easiest on Linux and relatively straightforward on Mac. For Windows, we currently recommend using the Docker image (described below) to build Pyodide.
Build using make
¶
Make sure the prerequisites for emsdk are installed. Pyodide will build a custom, patched version of emsdk, so there is no need to build it yourself prior.
Additional build prerequisites are:
A working native compiler toolchain, enough to build CPython.
A native Python 3.8 to run the build scripts.
CMake
PyYAML
FreeType 2 development libraries to compile Matplotlib.
lessc to compile less to css.
uglifyjs to minify Javascript builds.
gfortran (GNU Fortran 95 compiler)
ccache (optional) highly recommended for much faster rebuilds.
On Mac, you will also need:
Homebrew for installing dependencies
System libraries in the root directory (
sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /
should do it, see https://github.com/pyenv/pyenv/issues/1219#issuecomment-428305417)coreutils for md5sum and other essential Unix utilities (
brew install coreutils
)cmake (
brew install cmake
)pkg-config (
brew install pkg-config
)openssl (
brew install openssl
)gfortran (
brew cask install gfortran
)f2c: Install wget (
brew install wget
), and then run the buildf2c script from the root directory (sudo ./tools/buildf2c
)
After installing the build prerequisites, run from the command line:
make
Using Docker¶
We provide a Debian-based Docker image on Docker Hub with the dependencies already installed to make it easier to build Pyodide. On top of that we provide a pre-built image which can be used for fast custom and partial builds of pyodide. Note that building from the non pre-built the Docker image is very slow on Mac, building on the host machine is preferred if at all possible.
Install Docker
From a git checkout of Pyodide, run
./run_docker
or./run_docker --pre-built
Run
make
to build.
Note: You can control the resources allocated to the build by setting the env vars
EMSDK_NUM_CORE
, EMCC_CORES
and PYODIDE_JOBS
(the default for each is 4).
If running make
deterministically stops at one point in each subsequent try, increasing
the maximum RAM usage available to the docker container might help [This is different
from the physical RAM capacity inside the system]. Ideally, at least 3 GB of RAM
should be available to the docker container to build pyodide
smoothly. These settings can
be changed via Docker Preferences (See here).
You can edit the files in your source checkout on your host machine, and then
repeatedly run make
inside the Docker environment to test your changes.
Partial builds¶
To build a subset of available packages in pyodide, set the environment
variable PYODIDE_PACKAGES
to a comma separated list of packages. For
instance,
PYODIDE_PACKAGES="toolz,attrs" make
Dependencies of the listed packages will be built automatically as well.
The package names must match the folder names in packages/
exactly; in
particular they are case sensitive.
To build a minimal version of pyodide, set PYODIDE_PACKAGES="micropip"
. The
packages micropip and distutils are always automatically included (but an empty
PYODIDE_PACKAGES
is interpreted as unset).
Environment variables¶
Following environment variables additionally impact the build,
PYODIDE_JOBS
: the-j
option passed to theemmake make
command when applicable for parallel compilation. Default: 3.PYODIDE_BASE_URL
: Base URL where pyodide packages are deployed. It must end with a trailing/
. Default:./
to load pyodide packages from the same base URL path as wherepyodide.js
is located. Example:https://cdn.jsdelivr.net/pyodide/dev/full/