build will fail if only python3 avaiable #38791

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1. targos commented on May 24, 2021

   

   targos

   on May 24, 2021

   Member

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   It's because actions that run Python in our gypfiles directly reference the python executable:

   node/tools/v8_gypfiles/v8.gyp

   Line 1661 in e9e851f

   'python',

   Maybe we should do something in GYP to expose sys.executable as a variable?
2. targos

   added

   gypIssues and PRs related to GYP and .gyp or .gypi build files.Issues and PRs related to GYP and .gyp or .gypi build files.

   pythonPRs and issues that require attention from people who are familiar with Python.PRs and issues that require attention from people who are familiar with Python.

   on May 24, 2021
3. richardlau commented on May 24, 2021

   

   richardlau

   on May 24, 2021

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   I believe this is only an issue for building with Ninja. With make our configure scripts write out the path to Python as the PYTHON make variable via config.mk but also create a symbolic python link to sys.executable if it's not the same binary as python on the PATH and append the directory containing the link to PATH:
   

   node/configure.py

   Lines 1952 to 1954 in e9e851f

   	# Not needed for trivial case. Useless when it's a win32 path.
   	if sys.executable != 'python' and ':\\' not in sys.executable:
   	config['PYTHON'] = sys.executable

   
   

   node/configure.py

   Lines 1971 to 1976 in e9e851f

   	# On Windows there's no reason to search for a different python binary.
   	bin_override = None if sys.platform == 'win32' else make_bin_override()
   	if bin_override:
   	config_str = 'export PATH:=' + bin_override + ':$(PATH)\n' + config_str
   	write('config.mk', do_not_edit + config_str)

   
   

   node/configure.py

   Lines 1837 to 1868 in e9e851f

   	def make_bin_override():
   	if sys.platform == 'win32':
   	raise Exception('make_bin_override should not be called on win32.')
   	# If the system python is not the python we are running (which should be
   	# python 3), then create a directory with a symlink called `python` to our
   	# sys.executable. This directory will be prefixed to the PATH, so that
   	# other tools that shell out to `python` will use the appropriate python
   	which_python = which('python')
   	if (which_python and
   	os.path.realpath(which_python) == os.path.realpath(sys.executable)):
   	return
   	bin_override = os.path.abspath('out/tools/bin')
   	try:
   	os.makedirs(bin_override)
   	except OSError as e:
   	if e.errno != errno.EEXIST: raise e
   	python_link = os.path.join(bin_override, 'python')
   	try:
   	os.unlink(python_link)
   	except OSError as e:
   	if e.errno != errno.ENOENT: raise e
   	os.symlink(sys.executable, python_link)
   	# We need to set the environment right now so that when gyp (in run_gyp)
   	# shells out, it finds the right python (specifically at
   	# https://github.com/nodejs/node/blob/d82e107/deps/v8/gypfiles/toolchain.gypi#L43)
   	os.environ['PATH'] = bin_override + ':' + os.environ['PATH']
   	return bin_override

   (FWIW this is also the reason the V8 CI builds fail when Node.js' configure is run with Python 3 as the override means #!/usr/bin/env python ends up pointing to the Python 3 binary configure was run with instead of the default python.)
4. gengjiawen

   closed this as completedon Oct 19, 2021
5. gengjiawen

   reopened this on Oct 19, 2021
6. skys215 commented on Mar 16, 2022

   

   skys215

   on Mar 16, 2022

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   Am I the only one face the same problem after upgrading macos to 12.3?

   npm ERR! gyp info using node-gyp@3.5.0
   npm ERR! gyp info using node@17.7.1 | darwin | x64
   npm ERR! gyp verb command rebuild []
   npm ERR! gyp verb command clean []
   npm ERR! gyp verb clean removing "build" directory
   npm ERR! gyp verb command configure []
   npm ERR! gyp verb check python checking for Python executable "/usr/bin/python" in the PATH
   npm ERR! gyp verb `which` failed Error: not found: /usr/bin/python
   

   npm ERR! gyp ERR! configure error
   npm ERR! gyp ERR! stack Error: Can't find Python executable "/usr/bin/python", you can set the PYTHON env variable.
   

   ~> echo $PYTHON
   /usr/local/bin/python3
   
7. gengjiawen

   closed this as completedon Aug 9, 2023