From 604926b38ff8f41df6aa5347e57ac266c88d0afa Mon Sep 17 00:00:00 2001 From: Jan Provaznik Date: Mon, 10 Mar 2014 09:46:44 -0400 Subject: [PATCH] Adds "element-provides" support to element dependencies An element can define a list of elements provided by itself. This allows using an alternative element and keeping element dependencies at the same time. This will be needed for example for mariadb element which will be an alternative to mysql element - mysql dependency can be kept everywhere but user can choose mariadb explicitly as a replacement by putting "mysql" into "element-provides" file. Change-Id: I7f193612f279dd71d9f1f1edfc60009838a00c5a --- README.md | 14 ++++-- diskimage_builder/element_dependencies.py | 53 ++++++++++++++++----- diskimage_builder/tests/test_elementdeps.py | 23 ++++++++- 3 files changed, 73 insertions(+), 17 deletions(-) diff --git a/README.md b/README.md index 1e71a52b3..08226c6d3 100644 --- a/README.md +++ b/README.md @@ -325,9 +325,17 @@ scripts in each phase. ### Dependencies ### -Each element has a file named element-deps: a plain text, newline separated -list of elements which will be added to the list of elements built into the -image at image creation time. +Each element can use the following files to define or affect dependencies: + +* element-deps: a plain text, newline separated list of elements which will + be added to the list of elements built into the image at image creation time. + +* element-provides: A plain text, newline separated list of elements which + are provided by this element. These elements will be excluded from elements + built into the image at image creation time. For example if element A depends + on element B and element C includes element B in its "element-provides" + file and A and C are included when building an image, then B is not used. + ### First-boot files ### diff --git a/diskimage_builder/element_dependencies.py b/diskimage_builder/element_dependencies.py index 372cf9644..76c63a86e 100644 --- a/diskimage_builder/element_dependencies.py +++ b/diskimage_builder/element_dependencies.py @@ -24,21 +24,12 @@ def get_elements_dir(): return os.environ['ELEMENTS_PATH'] -def dependencies(element, elements_dir=None): - """Return the non-transitive list of dependencies for a single element. - - :param user_elements: iterable enumerating elements a user has requested - :param elements_dir: the elements dir to read from. If not supplied, - inferred by calling get_elements_dir(). - - :return: a set just containing all elements that the specified element - depends on. - """ +def _get_set(element, fname, elements_dir=None): if elements_dir is None: elements_dir = get_elements_dir() for path in elements_dir.split(':'): - element_deps_path = (os.path.join(path, element, 'element-deps')) + element_deps_path = (os.path.join(path, element, fname)) try: with open(element_deps_path) as element_deps: return set([line.strip() for line in element_deps]) @@ -55,6 +46,32 @@ def dependencies(element, elements_dir=None): exit(-1) +def provides(element, elements_dir=None): + """Return the set of elements provided by the specified element. + + :param element: name of a single element + :param elements_dir: the elements dir to read from. If not supplied, + inferred by calling get_elements_dir(). + + :return: a set just containing all elements that the specified element + provides. + """ + return _get_set(element, 'element-provides', elements_dir) + + +def dependencies(element, elements_dir=None): + """Return the non-transitive set of dependencies for a single element. + + :param element: name of a single element + :param elements_dir: the elements dir to read from. If not supplied, + inferred by calling get_elements_dir(). + + :return: a set just containing all elements that the specified element + depends on. + """ + return _get_set(element, 'element-deps', elements_dir) + + def expand_dependencies(user_elements, elements_dir=None): """Expand user requested elements using element-deps files. @@ -68,14 +85,24 @@ def expand_dependencies(user_elements, elements_dir=None): """ final_elements = set(user_elements) check_queue = list(user_elements) + provided = set() while check_queue: element = check_queue.pop() + if element in provided: + continue deps = dependencies(element, elements_dir) - check_queue.extend(deps - final_elements) + provided.update(provides(element, elements_dir)) + check_queue.extend(deps - (final_elements | provided)) final_elements.update(deps) - return final_elements + conflicts = set(user_elements) & provided + if conflicts: + sys.stderr.write("ERROR: Following elements were explicitly required " + "but are provided by other included elements: %s\n" % + ", ".join(conflicts)) + exit(-1) + return final_elements - provided def main(argv): diff --git a/diskimage_builder/tests/test_elementdeps.py b/diskimage_builder/tests/test_elementdeps.py index fc99f0ba0..0c945d291 100644 --- a/diskimage_builder/tests/test_elementdeps.py +++ b/diskimage_builder/tests/test_elementdeps.py @@ -24,12 +24,15 @@ data_dir = os.path.abspath( os.path.join(os.path.dirname(__file__), 'test-elements')) -def _populate_element(element_dir, element_name, element_deps=[]): +def _populate_element(element_dir, element_name, element_deps=[], provides=[]): element_home = os.path.join(element_dir, element_name) os.mkdir(element_home) deps_path = os.path.join(element_home, 'element-deps') with open(deps_path, 'w') as deps_file: deps_file.write("\n".join(element_deps)) + provides_path = os.path.join(element_home, 'element-provides') + with open(provides_path, 'w') as provides_file: + provides_file.write("\n".join(provides)) class TestElementDeps(testtools.TestCase): @@ -43,6 +46,12 @@ class TestElementDeps(testtools.TestCase): 'requires-requires-foo', ['requires-foo']) _populate_element(self.element_dir, 'self', ['self']) + _populate_element(self.element_dir, + 'provides_virtual', + [], + ['virtual']) + _populate_element(self.element_dir, 'requires_virtual', ['virtual']) + _populate_element(self.element_dir, 'virtual', []) _populate_element(self.element_dir, 'circular1', ['circular2']) _populate_element(self.element_dir, 'circular2', ['circular1']) @@ -79,6 +88,18 @@ class TestElementDeps(testtools.TestCase): ['circular1'], elements_dir=self.element_dir) self.assertEqual(set(['circular1', 'circular2']), result) + def test_provide(self): + result = element_dependencies.expand_dependencies( + ['requires_virtual', 'provides_virtual'], + elements_dir=self.element_dir) + self.assertEqual(set(['requires_virtual', 'provides_virtual']), result) + + def test_provide_conflict(self): + self.assertRaises(SystemExit, + element_dependencies.expand_dependencies, + ['virtual', 'provides_virtual'], + self.element_dir) + class TestElements(testtools.TestCase): def test_depends_on_env(self):