1 files changed, 59 insertions, 0 deletions
diff --git a/migrations/004-install-files-overwrite-symlink.py b/migrations/004-install-files-overwrite-symlink.py
new file mode 100755
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+++ b/migrations/004-install-files-overwrite-symlink.py
@@ -0,0 +1,59 @@
+#!/usr/bin/env python
+# Copyright (C) 2015  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/>.
+
+'''Migration to Baserock Definitions format version 4.
+
+This change to the format was made to work around a bug in a deployment
+extension present in morph.git.
+
+Automated migration is not really possible for this change, and unless you
+are experiencing the install-files.configure extension crashing, you can ignore
+it completely.
+
+We have now moved all .configure and .write extensions into the definitions.git
+repository. Changes like this no longer require a marking a new version of the
+Baserock definitions format in order to prevent build tools crashing.
+
+Morph commit c373f5a403b0ec introduces version 4 of the definitions format. In
+older versions of Morph the install-files.configure extension would crash if it
+tried to overwrite a symlink. This bug is fixed in the version of Morph that
+can build definitions version 4.
+
+If you need to overwrite a symlink at deploytime using install-files.configure,
+please use VERSION to 4 or above in your definitions.git repo so older versions
+of Morph gracefully refuse to deploy, instead of crashing.
+
+'''
+
+
+import sys
+
+import migrations
+
+
+TO_VERSION = 4
+
+
+try:
+    if migrations.check_definitions_version(TO_VERSION - 1):
+        migrations.set_definitions_version(TO_VERSION)
+        sys.stdout.write("Migration completed successfully.\n")
+        sys.exit(0)
+    else:
+        sys.stdout.write("Nothing to do.\n")
+        sys.exit(0)
+except RuntimeError as e:
+    sys.stderr.write("Error: %s\n" % e.message)
+    sys.exit(1)