[v2,2/2] bitbake-config-build: add a plugin for config fragments

diff --git a/meta-selftest/conf/fragments/selftest/test-another-fragment.conf b/meta-selftest/conf/fragments/selftest/test-another-fragment.conf
new file mode 100644
index 00000000000..4b4bf537964
--- /dev/null
+++ b/meta-selftest/conf/fragments/selftest/test-another-fragment.conf
@@ -0,0 +1,3 @@ 
+BB_CONF_FRAGMENT_SUMMARY[selftest/test-another-fragment] = "This is a second configuration fragment intended for testing in oe-selftest context"
+BB_CONF_FRAGMENT_DESCRIPTION[selftest/test-another-fragment] = "It defines another variable that can be checked inside the test."
+SELFTEST_FRAGMENT_ANOTHER_VARIABLE = "someothervalue"
diff --git a/meta-selftest/conf/fragments/selftest/test-fragment.conf b/meta-selftest/conf/fragments/selftest/test-fragment.conf
new file mode 100644
index 00000000000..63ebc1fca68
--- /dev/null
+++ b/meta-selftest/conf/fragments/selftest/test-fragment.conf
@@ -0,0 +1,3 @@ 
+BB_CONF_FRAGMENT_SUMMARY[selftest/test-fragment] = "This is a configuration fragment intended for testing in oe-selftest context"
+BB_CONF_FRAGMENT_DESCRIPTION[selftest/test-fragment] = "It defines a variable that can be checked inside the test."
+SELFTEST_FRAGMENT_VARIABLE = "somevalue"
diff --git a/meta/lib/bbconfigbuild/configfragments.py b/meta/lib/bbconfigbuild/configfragments.py
new file mode 100644
index 00000000000..f0d6e87b8ff
--- /dev/null
+++ b/meta/lib/bbconfigbuild/configfragments.py
@@ -0,0 +1,138 @@ 
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+import logging
+import os
+import sys
+
+import bb.utils
+
+from bblayers.common import LayerPlugin
+
+logger = logging.getLogger('bitbake-config-layers')
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+def plugin_init(plugins):
+    return ConfigFragmentsPlugin()
+
+class ConfigFragmentsPlugin(LayerPlugin):
+    def get_fragment_info(self, path, name):
+        d = bb.data.init()
+        bb.parse.handle(path, d, True)
+        summary = d.getVarFlag('BB_CONF_FRAGMENT_SUMMARY', name)
+        description = d.getVarFlag('BB_CONF_FRAGMENT_DESCRIPTION', name)
+        if not summary:
+            raise Exception('Please add a one-line summary as BB_CONF_FRAGMENT_SUMMARY[{}] = \"...\" variable at the beginning of {}'.format(name, path))
+
+        if not description:
+            raise Exception('Please add a description as BB_CONF_FRAGMENT_DESCRIPTION[{}] = \"...\" variable at the beginning of {}'.format(name, path))
+
+        return summary, description
+
+    def discover_fragments(self):
+        fragments_path_prefix = self.tinfoil.config_data.getVar('OE_FRAGMENTS_PREFIX')
+        allfragments = {}
+        for layername in self.bbfile_collections:
+             layerdir = self.bbfile_collections[layername]
+             fragments = []
+             for topdir, dirs, files in os.walk(os.path.join(layerdir, fragments_path_prefix)):
+                 fragmentdir = topdir.split(fragments_path_prefix+'/')[-1]
+                 for fragmentfile in sorted(files):
+                     fragmentname = "/".join((fragmentdir, fragmentfile.split('.')[0]))
+                     fragmentpath = os.path.join(topdir, fragmentfile)
+                     fragmentsummary, fragmentdesc = self.get_fragment_info(fragmentpath, fragmentname)
+                     fragments.append({'path':fragmentpath, 'name':fragmentname, 'summary':fragmentsummary, 'description':fragmentdesc})
+             if fragments:
+                 allfragments[layername] = {'layerdir':layerdir,'fragments':fragments}
+        return allfragments
+
+    def do_list_fragments(self, args):
+        """ List available configuration fragments """
+        enabled_fragments = (self.tinfoil.config_data.getVar('OE_FRAGMENTS') or "").split()
+
+        for layername, layerdata in self.discover_fragments().items():
+            layerdir = layerdata['layerdir']
+            fragments = layerdata['fragments']
+
+            print('Available fragments in {} layer located in {}:\n'.format(layername, layerdir))
+            for f in fragments:
+                if not args.verbose:
+                    print('{}\t{}\t{}'.format(f['name'], '(enabled)' if f['name'] in enabled_fragments else '(disabled)', f['summary']))
+                else:
+                    print('Name: {}\nPath: {}\nEnabled: {}\nSummary: {}\nDescription:\n{}\n'.format(f['name'], f['path'], 'yes' if f['name'] in enabled_fragments else 'no', f['summary'],''.join(f['description'])))
+            print('')
+
+    def fragment_exists(self, fragmentname):
+        for layername, layerdata in self.discover_fragments().items():
+            for f in layerdata['fragments']:
+              if f['name'] == fragmentname:
+                  return True
+        return False
+
+    def read_conf(self, confpath):
+        try:
+            with open(confpath) as f:
+                lines = f.readlines()
+        except Exception:
+            lines = []
+        return lines
+
+    def do_enable_fragment(self, args):
+        """ Enable a fragment in the local build configuration """
+        if not self.fragment_exists(args.fragmentname):
+            raise Exception("Fragment {} does not exist; use 'list-fragments' to see the full list.".format(args.fragmentname))
+
+        appendline = "OE_FRAGMENTS += \"{}\"\n".format(args.fragmentname)
+
+        lines = self.read_conf(args.confpath)
+        for l in lines:
+            if l == appendline:
+                print("Fragment {} already included in {}".format(args.fragmentname, args.confpath))
+                return
+
+        lines.append(appendline)
+        with open(args.confpath, 'w') as f:
+            f.write(''.join(lines))
+        print("Fragment {} added to {}.".format(args.fragmentname, args.confpath))
+
+    def do_disable_fragment(self, args):
+        """ Disable a fragment in the local build configuration """
+        removeline = "OE_FRAGMENTS += \"{}\"\n".format(args.fragmentname)
+
+        lines = [l for l in self.read_conf(args.confpath) if l != removeline]
+
+        with open(args.confpath, 'w') as f:
+            f.write(''.join(lines))
+        print("Fragment {} removed from {}.".format(args.fragmentname, args.confpath))
+
+    def do_disable_all_fragments(self, args):
+        """ Disable all fragments in the local build configuration """
+        removeline = "OE_FRAGMENTS += "
+
+        lines = [l for l in self.read_conf(args.confpath) if not l.startswith(removeline)]
+
+        with open(args.confpath, 'w') as f:
+            f.write(''.join(lines))
+        print("All fragment removed from {}.".format(args.confpath))
+
+    def register_commands(self, sp):
+        default_confpath = os.path.join(os.environ["BBPATH"], "conf/auto.conf")
+
+        parser_list_fragments = self.add_command(sp, 'list-fragments', self.do_list_fragments, parserecipes=False)
+        parser_list_fragments.add_argument("--confpath", default=default_confpath, help='Configuration file which contains a list of enabled fragments (default is {}).'.format(default_confpath))
+        parser_list_fragments.add_argument('--verbose', '-v', action='store_true', help='Print extended descriptions of the fragments')
+
+        parser_enable_fragment = self.add_command(sp, 'enable-fragment', self.do_enable_fragment, parserecipes=False)
+        parser_enable_fragment.add_argument("--confpath", default=default_confpath, help='Configuration file which contains a list of enabled fragments (default is {}).'.format(default_confpath))
+        parser_enable_fragment.add_argument('fragmentname', help='The name of the fragment (use list-fragments to see them)')
+
+        parser_disable_fragment = self.add_command(sp, 'disable-fragment', self.do_disable_fragment, parserecipes=False)
+        parser_disable_fragment.add_argument("--confpath", default=default_confpath, help='Configuration file which contains a list of enabled fragments (default is {}).'.format(default_confpath))
+        parser_disable_fragment.add_argument('fragmentname', help='The name of the fragment')
+
+        parser_disable_all = self.add_command(sp, 'disable-all-fragments', self.do_disable_all_fragments, parserecipes=False)
+        parser_disable_all.add_argument("--confpath", default=default_confpath, help='Configuration file which contains a list of enabled fragments (default is {}).'.format(default_confpath))
diff --git a/meta/lib/oeqa/selftest/cases/bblayers.py b/meta/lib/oeqa/selftest/cases/bblayers.py
index 695d17377d4..e15cf2d5707 100644
--- a/meta/lib/oeqa/selftest/cases/bblayers.py
+++ b/meta/lib/oeqa/selftest/cases/bblayers.py
@@ -240,3 +240,34 @@  class BitbakeLayers(OESelftestTestCase):
         self.assertEqual(first_desc_2, '', "Describe not cleared: '{}'".format(first_desc_2))
         self.assertEqual(second_rev_2, second_rev_1, "Revision should not be updated: '{}'".format(second_rev_2))
         self.assertEqual(second_desc_2, second_desc_1, "Describe should not be updated: '{}'".format(second_desc_2))
+
+class BitbakeConfigBuild(OESelftestTestCase):
+    def test_add_remove_fragments(self):
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_VARIABLE'), None)
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_ANOTHER_VARIABLE'), None)
+
+        runCmd('bitbake-config-build enable-fragment selftest/test-fragment')
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_VARIABLE'), 'somevalue')
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_ANOTHER_VARIABLE'), None)
+
+        runCmd('bitbake-config-build enable-fragment selftest/test-another-fragment')
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_VARIABLE'), 'somevalue')
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_ANOTHER_VARIABLE'), 'someothervalue')
+
+        fragment_metadata_command = "bitbake-getvar -f {} --value {}"
+        result = runCmd(fragment_metadata_command.format("selftest/test-fragment", "BB_CONF_FRAGMENT_SUMMARY"))
+        self.assertIn("This is a configuration fragment intended for testing in oe-selftest context", result.output)
+        result = runCmd(fragment_metadata_command.format("selftest/test-fragment", "BB_CONF_FRAGMENT_DESCRIPTION"))
+        self.assertIn("It defines a variable that can be checked inside the test.", result.output)
+        result = runCmd(fragment_metadata_command.format("selftest/test-another-fragment", "BB_CONF_FRAGMENT_SUMMARY"))
+        self.assertIn("This is a second configuration fragment intended for testing in oe-selftest context", result.output)
+        result = runCmd(fragment_metadata_command.format("selftest/test-another-fragment", "BB_CONF_FRAGMENT_DESCRIPTION"))
+        self.assertIn("It defines another variable that can be checked inside the test.", result.output)
+
+        runCmd('bitbake-config-build disable-fragment selftest/test-fragment')
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_VARIABLE'), None)
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_ANOTHER_VARIABLE'), 'someothervalue')
+
+        runCmd('bitbake-config-build disable-fragment selftest/test-another-fragment')
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_VARIABLE'), None)
+        self.assertEqual(get_bb_var('SELFTEST_FRAGMENT_ANOTHER_VARIABLE'), None)