Refactor setup.py helper code

setup.py

@@ -1,4 +1,6 @@
 
+from __future__ import print_function
+
 import json
 import os
 import os.path
@@ -16,7 +18,7 @@
 except ImportError:
     print("Ansible now needs setuptools in order to build. Install it using"
           " your package manager (usually python-setuptools) or via pip (pip"
-          " install setuptools).")
+          " install setuptools).", file=sys.stderr)
     sys.exit(1)
 
 sys.path.insert(0, os.path.abspath('lib'))
@@ -49,7 +51,7 @@ def _find_symlinks(topdir, extension=''):
 
 def _cache_symlinks(symlink_data):
     with open(SYMLINK_CACHE, 'w') as f:
-        f.write(json.dumps(symlink_data))
+        json.dump(symlink_data, f)
 
 
 def _maintain_symlinks(symlink_type, base_path):
@@ -58,7 +60,7 @@ def _maintain_symlinks(symlink_type, base_path):
         # Try the cache first because going from git checkout to sdist is the
         # only time we know that we're going to cache correctly
         with open(SYMLINK_CACHE, 'r') as f:
-            symlink_data = json.loads(f.read())
+            symlink_data = json.load(f)
     except (IOError, OSError) as e:
         # IOError on py2, OSError on py3.  Both have errno
         if e.errno == 2:
@@ -129,41 +131,87 @@ def run(self):
         SDist.run(self)
 
 
-with open('requirements.txt') as requirements_file:
-    install_requirements = requirements_file.read().splitlines()
-    if not install_requirements:
-        print("Unable to read requirements from the requirements.txt file"
-              "That indicates this copy of the source code is incomplete.")
-        sys.exit(2)
-
-# pycrypto or cryptography.   We choose a default but allow the user to
-# override it.  This translates into pip install of the sdist deciding what
-# package to install and also the runtime dependencies that pkg_resources
-# knows about
-crypto_backend = os.environ.get('ANSIBLE_CRYPTO_BACKEND', None)
-if crypto_backend:
-    if crypto_backend.strip() == 'pycrypto':
+def read_file(file_name):
+    """Read file and return its contents."""
+    with open(file_name, 'r') as f:
+        return f.read()
+
+
+def read_requirements(file_name):
+    """Read requirements file as a list."""
+    reqs = read_file(file_name).splitlines()
+    if not reqs:
+        raise RuntimeError(
+            "Unable to read requirements from the %s file"
+            "That indicates this copy of the source code is incomplete."
+            % file_name
+        )
+    return reqs
+
+
+PYCRYPTO_DIST = 'pycrypto'
+
+
+def get_crypto_req():
+    """Detect custom crypto from ANSIBLE_CRYPTO_BACKEND env var.
+
+    pycrypto or cryptography. We choose a default but allow the user to
+    override it. This translates into pip install of the sdist deciding what
+    package to install and also the runtime dependencies that pkg_resources
+    knows about.
+    """
+    crypto_backend = os.environ.get('ANSIBLE_CRYPTO_BACKEND', '').strip()
+
+    if crypto_backend == PYCRYPTO_DIST:
         # Attempt to set version requirements
-        crypto_backend = 'pycrypto >= 2.6'
+        return '%s >= 2.6' % PYCRYPTO_DIST
+
+    return crypto_backend or None
+
+
+def substitute_crypto_to_req(req):
+    """Replace crypto requirements if customized."""
+    crypto_backend = get_crypto_req()
+
+    if crypto_backend is None:
+        return req
+
+    def is_not_crypto(r):
+        CRYPTO_LIBS = PYCRYPTO_DIST, 'cryptography'
+        return not any(r.lower().startswith(c) for c in CRYPTO_LIBS)
+
+    return [r for r in req if is_not_crypto(r)] + [crypto_backend]
+
 
-    install_requirements = [r for r in install_requirements if not (r.lower().startswith('pycrypto') or r.lower().startswith('cryptography'))]
-    install_requirements.append(crypto_backend)
+def read_extras():
+    """Specify any extra requirements for installation."""
+    extras = dict()
+    extra_requirements_dir = 'packaging/requirements'
+    for extra_requirements_filename in os.listdir(extra_requirements_dir):
+        filename_match = re.search(r'^requirements-(\w*).txt$', extra_requirements_filename)
+        if not filename_match:
+            continue
+        extra_req_file_path = os.path.join(extra_requirements_dir, extra_requirements_filename)
+        try:
+            extras[filename_match.group(1)] = read_file(extra_req_file_path).splitlines()
+        except RuntimeError:
+            pass
+    return extras
 
-# specify any extra requirements for installation
-extra_requirements = dict()
-extra_requirements_dir = 'packaging/requirements'
-for extra_requirements_filename in os.listdir(extra_requirements_dir):
-    filename_match = re.search(r'^requirements-(\w*).txt$', extra_requirements_filename)
-    if filename_match:
-        with open(os.path.join(extra_requirements_dir, extra_requirements_filename)) as extra_requirements_file:
-            extra_requirements[filename_match.group(1)] = extra_requirements_file.read().splitlines()
 
-# Retrieve the long description from the README
-with open('README.rst', 'r') as readme_file:
-    longdesc = readme_file.read()
+def get_dynamic_setup_params():
+    """Add dynamically calculated setup params to static ones."""
+    return {
+        # Retrieve the long description from the README
+        'long_description': read_file('README.rst'),
+        'install_requires': substitute_crypto_to_req(
+            read_requirements('requirements.txt'),
+        ),
+        'extras_require': read_extras(),
+    }
 
 
-setup_params = dict(
+static_setup_params = dict(
     # Use the distutils SDist so that symlinks are not expanded
     # Use a custom Build for the same reason
     cmdclass={
@@ -176,7 +224,6 @@ def run(self):
     name='ansible',
     version=__version__,
     description='Radically simple IT automation',
-    long_description=longdesc,
     author=__author__,
     author_email='info@ansible.com',
     url='https://ansible.com/',
@@ -189,7 +236,6 @@ def run(self):
     license='GPLv3+',
     # Ansible will also make use of a system copy of python-six and
     # python-selectors2 if installed but use a Bundled copy if it's not.
-    install_requires=install_requirements,
     python_requires='>=2.6,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*',
     package_dir={'': 'lib'},
     packages=find_packages('lib'),
@@ -237,14 +283,14 @@ def run(self):
         'bin/ansible-inventory',
     ],
     data_files=[],
-    extras_require=extra_requirements,
     # Installing as zip files would break due to references to __file__
     zip_safe=False
 )
 
 
 def main():
     """Invoke installation process using setuptools."""
+    setup_params = dict(static_setup_params, **get_dynamic_setup_params())
     setup(**setup_params)