Maintain symlinks in setup.py sdist, build, and install commands (#27149)

* Maintain symlinks in setup.py sdist, build, and install commands

Symlinks are meaningful for ansible modules.  They differentiate between
aliases and deprecated modules.  They're also useful for saving space
and where downstream patches should be applied to the bin scripts.

Fixes #27105

* Add a fallback for install and build to try to cache symlinks on their own

Needed when someone tries to invoke setup.py build or setup.py install
directly from the source checkout without an intermediate sdist.

MANIFEST.in

@@ -1,6 +1,7 @@
 prune ticket_stubs
 prune hacking
 include README.md COPYING
+include SYMLINK_CACHE.json
 include requirements.txt
 include .coveragerc
 include .yamllint

setup.py

@@ -1,17 +1,132 @@
+
+import json
 import os
 import os.path
 import sys
+from collections import defaultdict
+from distutils.command.build_scripts import build_scripts as BuildScripts
+from distutils.command.sdist import sdist as SDist
 
-sys.path.insert(0, os.path.abspath('lib'))
-from ansible.release import __version__, __author__
 try:
     from setuptools import setup, find_packages
+    from setuptools.command.build_py import build_py as BuildPy
+    from setuptools.command.install_lib import install_lib as InstallLib
+    from setuptools.command.install_scripts import install_scripts as InstallScripts
 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).")
     sys.exit(1)
 
+sys.path.insert(0, os.path.abspath('lib'))
+from ansible.release import __version__, __author__
+
+
+SYMLINK_CACHE = 'SYMLINK_CACHE.json'
+
+
+def _find_symlinks(topdir, extension=''):
+    """Find symlinks that should be maintained
+
+    Maintained symlinks exist in the bin dir or are modules which have
+    aliases.  Our heuristic is that they are a link in a certain path which
+    point to a file in the same directory.
+    """
+    symlinks = defaultdict(list)
+    for base_path, dirs, files in os.walk(topdir):
+        for filename in files:
+            filepath = os.path.join(base_path, filename)
+            if os.path.islink(filepath) and filename.endswith(extension):
+                target = os.readlink(filepath)
+                if os.path.dirname(target) == '':
+                    link = filepath[len(topdir):]
+                    if link.startswith('/'):
+                        link = link[1:]
+                    symlinks[os.path.basename(target)].append(link)
+    return symlinks
+
+
+def _cache_symlinks(symlink_data):
+    with open(SYMLINK_CACHE, 'w') as f:
+        f.write(json.dumps(symlink_data))
+
+
+def _maintain_symlinks(symlink_type, base_path):
+    """Switch a real file into a symlink"""
+    try:
+        # 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())
+    except IOError as e:
+        if e.errno == 2:
+            # SYMLINKS_CACHE doesn't exist.  Fallback to trying to create the
+            # cache now.  Will work if we're running directly from a git
+            # checkout or from an sdist created earlier.
+            symlink_data = {'script': _find_symlinks('bin'),
+                            'library': _find_symlinks('lib', '.py'),
+                            }
+
+            # Sanity check that something we know should be a symlink was
+            # found.  We'll take that to mean that the current directory
+            # structure properly reflects symlinks in the git repo
+            if 'ansible-playbook' in symlink_data['script']['ansible']:
+                _cache_symlinks(symlink_data)
+            else:
+                raise
+        else:
+            raise
+    symlinks = symlink_data[symlink_type]
+
+    for source in symlinks:
+        for dest in symlinks[source]:
+            dest_path = os.path.join(base_path, dest)
+            if not os.path.islink(dest_path):
+                try:
+                    os.unlink(dest_path)
+                except OSError as e:
+                    if e.errno == 2:
+                        # File does not exist which is all we wanted
+                        pass
+                os.symlink(source, dest_path)
+
+
+class BuildPyCommand(BuildPy):
+    def run(self):
+        BuildPy.run(self)
+        _maintain_symlinks('library', self.build_lib)
+
+
+class BuildScriptsCommand(BuildScripts):
+    def run(self):
+        BuildScripts.run(self)
+        _maintain_symlinks('script', self.build_dir)
+
+
+class InstallLibCommand(InstallLib):
+    def run(self):
+        InstallLib.run(self)
+        _maintain_symlinks('library', self.install_dir)
+
+
+class InstallScriptsCommand(InstallScripts):
+    def run(self):
+        InstallScripts.run(self)
+        _maintain_symlinks('script', self.install_dir)
+
+
+class SDistCommand(SDist):
+    def run(self):
+        # have to generate the cache of symlinks for release as sdist is the
+        # only command that has access to symlinks from the git repo
+        symlinks = {'script': _find_symlinks('bin'),
+                    'library': _find_symlinks('lib', '.py'),
+                    }
+        _cache_symlinks(symlinks)
+
+        SDist.run(self)
+
+
 with open('requirements.txt') as requirements_file:
     install_requirements = requirements_file.read().splitlines()
     if not install_requirements:
@@ -33,26 +148,16 @@ if crypto_backend:
     install_requirements.append(crypto_backend)
 
 
-SYMLINKS = {'ansible': frozenset(('ansible-console',
-                                  'ansible-doc',
-                                  'ansible-galaxy',
-                                  'ansible-playbook',
-                                  'ansible-pull',
-                                  'ansible-vault'))}
-
-for source in SYMLINKS:
-    for dest in SYMLINKS[source]:
-        dest_path = os.path.join('bin', dest)
-        if not os.path.islink(dest_path):
-            try:
-                os.unlink(dest_path)
-            except OSError as e:
-                if e.errno == 2:
-                    # File does not exist which is all we wanted
-                    pass
-            os.symlink(source, dest_path)
-
 setup(
+    # Use the distutils SDist so that symlinks are not expanded
+    # Use a custom Build for the same reason
+    cmdclass={
+        'build_py': BuildPyCommand,
+        'build_scripts': BuildScriptsCommand,
+        'install_lib': InstallLibCommand,
+        'install_scripts': InstallScriptsCommand,
+        'sdist': SDistCommand,
+    },
     name='ansible',
     version=__version__,
     description='Radically simple IT automation',