initial fix-ref plugin

Change-Id: Ib0af85cd3529d865a8b17a5461acdeecccb5f52d

1 files changed, 127 insertions, 0 deletions

diff --git a/morphlib/plugins/fix_ref.py b/morphlib/plugins/fix_ref.py
new file mode 100644
index 00000000..7e65647d
--- /dev/null
+++ b/morphlib/plugins/fix_ref.py
@@ -0,0 +1,127 @@
+# Copyright (C) 2016  Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import cliapp
+import contextlib
+import glob
+import logging
+import os
+import shutil
+
+import morphlib
+
+
+class FixRefPlugin(cliapp.Plugin):
+   '''Add subcommands for handling workspaces and system branches.'''
+
+    def enable(self):
+        self.app.add_subcommand(
+            'fix', self.petrify, arg_synopsis='')
+        self.app.add_subcommand(
+            'unfix', self.unpetrify, arg_synopsis='')
+
+    def petrify(self, args):
+        '''Convert all chunk refs in a system branch to be fixed SHA1s.
+
+        This modifies all git commit references in system and stratum
+        morphologies, in the current system branch, to be fixed SHA
+        commit identifiers, rather than symbolic branch or tag names.
+        This is useful for making sure none of the components in a system
+        branch change accidentally.
+
+        Consider the following scenario:
+
+        * The `master` system branch refers to `gcc` using the
+          `baserock/morph` ref. This is appropriate, since the main line
+          of development should use the latest curated code.
+
+        * You create a system branch to prepare for a release, called
+          `TROVE_ID/release/2.0`. The reference to `gcc` is still
+          `baserock/morph`.
+
+        * You test everything, and make a release. You deploy the release
+          images onto devices, which get shipped to your customers.
+
+        * A new version GCC is committed to the `baserock/morph` branch.
+
+        * Your release branch suddenly uses a new compiler, which may
+          or may not work for your particular system at that release.
+
+        To avoid this, you need to _petrify_ all git references
+        so that they do not change accidentally. If you've tested
+        your release with the GCC release that is stored in commit
+        `94c50665324a7aeb32f3096393ec54b2e63bfb28`, then you should
+        continue to use that version of GCC, regardless of what might
+        happen in the master system branch. If, and only if, you decide
+        that a new compiler would be good for your release should you
+        include it in your release branch. This way, only the things
+        that you change intentionally change in your release branch.
+
+        '''
+
+        if args:
+            raise cliapp.AppException('morph petrify takes no arguments')
+
+        ws = morphlib.workspace.open('.')
+        sb = morphlib.sysbranchdir.open_from_within('.')
+        loader = morphlib.morphloader.MorphologyLoader()
+        lrc, rrc = morphlib.util.new_repo_caches(self.app)
+        update_repos = not self.app.settings['no-git-update']
+
+        morphs = self._load_all_sysbranch_morphologies(sb, loader)
+
+        #TODO: Stop using app.resolve_ref
+        def resolve_refs(morphs):
+            for repo, ref in morphs.list_refs():
+                # You can't resolve null refs, so don't attempt to.
+                if repo is None or ref is None:
+                    continue
+                # TODO: Handle refs that are only in workspace in general
+                if (repo == sb.root_repository_url
+                    and ref == sb.system_branch_name):
+                    continue
+                commit_sha1, tree_sha1 = self.app.resolve_ref(
+                    lrc, rrc, repo, ref, update=update_repos)
+                yield ((repo, ref), commit_sha1)
+
+        morphs.repoint_refs(sb.root_repository_url,
+                            sb.system_branch_name)
+
+        morphs.petrify_chunks(dict(resolve_refs(morphs)))
+
+        # Write morphologies back out again.
+        self._save_dirty_morphologies(loader, sb, morphs.morphologies)
+
+    def unpetrify(self, args):
+        '''Reverse the process of petrification.
+
+        This undoes the changes `morph petrify` did.
+
+        '''
+
+        if args:
+            raise cliapp.AppException('morph petrify takes no arguments')
+
+        ws = morphlib.workspace.open('.')
+        sb = morphlib.sysbranchdir.open_from_within('.')
+        loader = morphlib.morphloader.MorphologyLoader()
+
+        morphs = self._load_all_sysbranch_morphologies(sb, loader)
+
+        # Restore the ref for each stratum and chunk
+        morphs.unpetrify_all()
+
+        # Write morphologies back out again.
+        self._save_dirty_morphologies(loader, sb, morphs.morphologies)