makeapi, makeaci: do not fail on missing imports

Add import hook to makeapi and makeaci which makes them ignore import
errors in modules in our source tree and instead print a warning.

This makes it possible to build IPA without having to have most of our
runtime dependencies installed.

https://fedorahosted.org/freeipa/ticket/6418

Reviewed-By: Petr Spacek <pspacek@redhat.com>
Reviewed-By: Martin Basti <mbasti@redhat.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/ignore_import_errors.py b/ignore_import_errors.py
new file mode 100644
index 000000000..4ee6ee98b
--- /dev/null
+++ b/ignore_import_errors.py
@@ -0,0 +1,87 @@
+#
+# Copyright (C) 2016  FreeIPA Contributors see COPYING for license
+#
+
+"""
+ImportError ignoring import hook.
+"""
+
+from __future__ import print_function
+
+import imp
+import inspect
+import os.path
+import sys
+
+DIRNAME = os.path.dirname(os.path.abspath(__file__))
+
+
+class FailedImport(object):
+    def __init__(self, loader, name):
+        self.__file__ = __file__
+        self.__name__ = name
+        self.__path__ = []
+        self.__loader__ = loader
+        self.__package__ = name
+
+    def __repr__(self):
+        return '<failed import {!r}>'.format(self.__name__)
+
+
+class IgnoringImporter(object):
+    def find_module(self, fullname, path=None):
+        parentname, dot, name = fullname.rpartition('.')
+        assert (not dot and path is None) or (dot and path is not None)
+
+        # check if the module can be found
+        try:
+            file, _filename, _description = imp.find_module(name, path)
+        except ImportError:
+            pass
+        else:
+            if file is not None:
+                file.close()
+            # it can be found, do normal import
+            return None
+
+        # check if the parent module import failed
+        if dot and isinstance(sys.modules[parentname], FailedImport):
+            # it did fail, so this import will fail as well
+            return self
+
+        # find out from where are we importing
+        if path is None:
+            path = sys.path
+        for pathname in path:
+            pathname = os.path.abspath(pathname)
+            if not pathname.startswith(DIRNAME):
+                break
+        else:
+            # importing from our source tree, do normal import
+            return None
+
+        # find out into what .py file are we importing
+        frame = inspect.currentframe().f_back
+        filename = frame.f_code.co_filename
+        if filename.startswith('<'):
+            # not a file, do normal import
+            return None
+        filename = os.path.abspath(filename)
+        if not filename.startswith(DIRNAME):
+            # not a file in our source tree, do normal import
+            return None
+
+        return self
+
+    def load_module(self, fullname):
+        frame = inspect.currentframe().f_back
+        print("{}: {}:{}: ignoring ImportError: No module named {}".format(
+                sys.argv[0],
+                os.path.relpath(frame.f_code.co_filename),
+                frame.f_lineno,
+                fullname))
+
+        return sys.modules.setdefault(fullname, FailedImport(self, fullname))
+
+
+sys.meta_path.insert(0, IgnoringImporter())