97980a8f94
The Python landscape is going to be changing in 2020, and Python 2 will be end of life. Spack should *prefer* Python 3 to Python 2 by default, but we still need to run on systems that only have Python2 available. This is trickier than it sounds, as on some systems, the `python` command is `python2`; on others it's `python3`, and RHEL8 doesn't even have the `python` command. Instead, it makes you choose `python3` or `python2`. You can thus no longer make a simple shebang to handle all the cases. This commit makes the `spack` script bilingual. It is still valid Python, but its shebang is `#!/bin/sh`, and it has a tiny bit of shell code at the beginning to pick the right python and execute itself with what it finds. This has a lot of advantages. I think this will help ensure that Spack works well in Python3 -- there are cases where we've missed things because Python2 is still the default `python` on most systems. Also, with this change, you do not lose the ability to execute the `spack` script directly with a python interpreter. This is useful for forcing your own version of python, running coverage tools, and running profiling tools. i.e., these will not break with this change: ```console $ python2 $(which spack) <args> $ coverage run $(which spack) <args> $ pyinstrument $(which spack) <args> ``` These would not work if we split `spack` into a python file and a shell script (see #11783). So, this gives us the best of both worlds. We get to control our interpreter *and* remain a mostly pure python executable.
65 lines
2.1 KiB
Python
Executable File
65 lines
2.1 KiB
Python
Executable File
#!/bin/sh
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# -*- python -*-
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#
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# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
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# Spack Project Developers. See the top-level COPYRIGHT file for details.
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#
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# SPDX-License-Identifier: (Apache-2.0 OR MIT)
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# This file is bilingual. The following shell code finds our preferred python.
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# Following line is a shell no-op, and starts a multi-line Python comment.
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# See https://stackoverflow.com/a/47886254
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""":"
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# prefer python3, then python, then python2
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for cmd in python3 python python2; do
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command -v > /dev/null $cmd && exec $cmd $0 "$@"
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done
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echo "==> Error: spack could not find a python interpreter!" >&2
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exit 1
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":"""
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# Line above is a shell no-op, and ends a python multi-line comment.
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# The code above runs this file with our preferred python interpreter.
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from __future__ import print_function
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import os
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import sys
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if sys.version_info[:2] < (2, 6):
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v_info = sys.version_info[:3]
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sys.exit("Spack requires Python 2.6 or higher."
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"This is Python %d.%d.%d." % v_info)
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# Find spack's location and its prefix.
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spack_file = os.path.realpath(os.path.expanduser(__file__))
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spack_prefix = os.path.dirname(os.path.dirname(spack_file))
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# Allow spack libs to be imported in our scripts
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spack_lib_path = os.path.join(spack_prefix, "lib", "spack")
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sys.path.insert(0, spack_lib_path)
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# Add external libs
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spack_external_libs = os.path.join(spack_lib_path, "external")
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if sys.version_info[:2] == (2, 6):
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sys.path.insert(0, os.path.join(spack_external_libs, 'py26'))
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sys.path.insert(0, spack_external_libs)
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# Here we delete ruamel.yaml in case it has been already imported from site
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# (see #9206 for a broader description of the issue).
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#
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# Briefly: ruamel.yaml produces a .pth file when installed with pip that
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# makes the site installed package the preferred one, even though sys.path
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# is modified to point to another version of ruamel.yaml.
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if 'ruamel.yaml' in sys.modules:
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del sys.modules['ruamel.yaml']
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if 'ruamel' in sys.modules:
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del sys.modules['ruamel']
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# Once we've set up the system path, run the spack main method
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import spack.main # noqa
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sys.exit(spack.main.main())
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