[1/5] bitbake-layers: add a command to save the active build configuration as a template into a layer

diff --git a/meta/lib/bblayers/buildconf.py b/meta/lib/bblayers/buildconf.py
new file mode 100644
index 0000000000..ece8836d5a
--- /dev/null
+++ b/meta/lib/bblayers/buildconf.py
@@ -0,0 +1,83 @@ 
+#
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+import logging
+import os
+import stat
+import sys
+import shutil
+import json
+
+import bb.utils
+import bb.process
+
+from bblayers.common import LayerPlugin
+
+logger = logging.getLogger('bitbake-layers')
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+import oe.buildcfg
+
+def plugin_init(plugins):
+    return BuildConfPlugin()
+
+class BuildConfPlugin(LayerPlugin):
+    notes_fixme = """FIXME: Please place here the description of this build configuration.
+It will be shown to the users when they set up their builds via TEMPLATECONF.
+"""
+
+    def _save_conf(self, templatename, templatepath, oecorepath, relpaths_to_oecore):
+        confdir = os.path.join(os.environ["BBPATH"], "conf")
+        destdir = os.path.join(templatepath, "conf", "templates", templatename)
+        os.makedirs(destdir, exist_ok=True)
+
+        with open(os.path.join(confdir, "local.conf")) as src:
+            with open(os.path.join(destdir, "local.conf.sample"), 'w') as dest:
+                dest.write(src.read())
+
+        with open(os.path.join(confdir, "bblayers.conf")) as src:
+            with open(os.path.join(destdir, "bblayers.conf.sample"), 'w') as dest:
+                bblayers_data = src.read()
+
+                for (abspath, relpath) in relpaths_to_oecore:
+                    bblayers_data = bblayers_data.replace(abspath, "##OEROOT##/" + relpath)
+                dest.write(bblayers_data)
+
+        with open(os.path.join(destdir, "conf-notes.txt"), 'w') as dest:
+            dest.write(self.notes_fixme)
+
+        logger.info("""Configuration template placed into {}
+Please review the files in there, and particularly provide a configuration description in {}
+You can try out the configuration with
+TEMPLATECONF={} . {}/oe-init-build-env build-try-{}"""
+.format(destdir, os.path.join(destdir, "conf-notes.txt"), destdir, oecorepath, templatename))
+
+    def do_save_build_conf(self, args):
+        """ Save the currently active build configuration (conf/local.conf, conf/bblayers.conf) as a template into a layer.\n This template can later be used for setting up builds via TEMPLATECONF. """
+        repos = {}
+        layers = oe.buildcfg.get_layer_revisions(self.tinfoil.config_data)
+        targetlayer = None
+        oecore = None
+
+        for l in layers:
+            if l[0] == os.path.abspath(args.layerpath):
+                targetlayer = l[0]
+            if l[1] == 'meta':
+                oecore = os.path.dirname(l[0])
+
+        if not targetlayer:
+            logger.error("Layer {} not in one of the currently enabled layers:\n{}".format(args.layerpath, "\n".join([l[0] for l in layers])))
+        elif not oecore:
+            logger.error("Openembedded-core not in one of the currently enabled layers:\n{}".format("\n".join([l[0] for l in layers])))
+        else:
+            relpaths_to_oecore = [(l[0], os.path.relpath(l[0], start=oecore)) for l in layers]
+            self._save_conf(args.templatename, targetlayer, oecore, relpaths_to_oecore)
+
+    def register_commands(self, sp):
+        parser_build_conf = self.add_command(sp, 'save-build-conf', self.do_save_build_conf, parserecipes=False)
+        parser_build_conf.add_argument('layerpath',
+            help='The path to the layer where the configuration template should be saved.')
+        parser_build_conf.add_argument('templatename',
+            help='The name of the configuration template.')
diff --git a/meta/lib/oeqa/selftest/cases/bblayers.py b/meta/lib/oeqa/selftest/cases/bblayers.py
index 494fa892a3..549abe7d10 100644
--- a/meta/lib/oeqa/selftest/cases/bblayers.py
+++ b/meta/lib/oeqa/selftest/cases/bblayers.py
@@ -113,6 +113,11 @@  class BitbakeLayers(OESelftestTestCase):
 
         self.assertEqual(bb_vars['BBFILE_PRIORITY_%s' % layername], str(priority), 'BBFILE_PRIORITY_%s != %d' % (layername, priority))
 
+        result = runCmd('bitbake-layers save-build-conf {} {}'.format(layerpath, "buildconf-1"))
+        for f in ('local.conf.sample', 'bblayers.conf.sample', 'conf-notes.txt'):
+            fullpath = os.path.join(layerpath, "conf", "templates", "buildconf-1", f)
+            self.assertTrue(os.path.exists(fullpath), "Template configuration file {} not found".format(fullpath))
+
     def get_recipe_basename(self, recipe):
         recipe_file = ""
         result = runCmd("bitbake-layers show-recipes -f %s" % recipe)