Thursday, 13 September 2018

node-gyp and Python support on Windows

node-gyp is a cross-platform command-line tool written in Node.js for compiling native addon modules for Node.js. [node-gyp on GitHub] [node-gyp]

If you try to run node-gyp on a machine with no Python installed you might get an error similar to this:

gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack at PythonFinder.failNoPython (C:\Users\user\AppData\Roaming\npm\node_modules\npm\node_modules\node-gyp\lib\configure.js:484:19)
gyp ERR! stack at PythonFinder. (C:\Users\user\AppData\Roaming\npm\node_modules\npm\node_modules\node-gyp\lib\configure.js:509:16)
gyp ERR! stack at C:\Users\user\AppData\Roaming\npm\node_modules\npm\node_modules\graceful-fs\polyfills.js:284:29
gyp ERR! stack at FSReqWrap.oncomplete (fs.js:158:21)
gyp ERR! System Windows_NT 10.0.17134
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Users\\user\\AppData\\Roaming\\npm\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
gyp ERR! cwd C:\whatever\my-app\node_modules\dtrace-provider
gyp ERR! node -v v10.7.0
gyp ERR! node-gyp -v v3.8.0
gyp ERR! not ok

(cwd in this output message stands for Current Working Directory)

If you have Python 3 installed, the same command will fail for Python 3 interpreter not be able to parse Python 2 code...This happens as node-gyp (still) doesn't support Python 3 so you'll need to install Python 2 (2.7.x).

When installing Python 2 DO NOT opt for adding its path to PATH environment variable as otherwise it will make Python 2 the default one on the machine.

The easiest way to make node-gyp working with Python 2 while not interfering with existing Python 3 paths is to follow the suggestion from the error message above, create PYTHON env variable and set its value to Python 2 path (C:\Python27). Then we can have this setup before we execute node node-gyp.js:

>python --version
Python 3.7.0

>echo %PYTHON%
C:\Python27


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