Add framework for watcher-status upgrade check

This commit adds the functionality of watcher-status CLI for performing
upgrade checks as part of the Stein cycle upgrade-checkers goal.
It only includes a sample check which must be replaced by real checks in
future.

Change-Id: Ic3d066af439797d6f705e805334f729b52ce3aac
Story: 2003657
Task: 26164

doc/source/man/index.rst

@@ -5,4 +5,5 @@
    watcher-api
    watcher-applier
    watcher-db-manage
-   watcher-decision-engine
+   watcher-decision-engine
+   watcher-status

doc/source/man/watcher-status.rst

@@ -0,0 +1,83 @@
+==============
+watcher-status
+==============
+
+-----------------------------------------
+CLI interface for Watcher status commands
+-----------------------------------------
+
+Synopsis
+========
+
+::
+
+  watcher-status <category> <command> [<args>]
+
+Description
+===========
+
+:program:`watcher-status` is a tool that provides routines for checking the
+status of a Watcher deployment.
+
+Options
+=======
+
+The standard pattern for executing a :program:`watcher-status` command is::
+
+    watcher-status <category> <command> [<args>]
+
+Run without arguments to see a list of available command categories::
+
+    watcher-status
+
+Categories are:
+
+* ``upgrade``
+
+Detailed descriptions are below:
+
+You can also run with a category argument such as ``upgrade`` to see a list of
+all commands in that category::
+
+    watcher-status upgrade
+
+These sections describe the available categories and arguments for
+:program:`Watcher-status`.
+
+Upgrade
+~~~~~~~
+
+.. _watcher-status-checks:
+
+``watcher-status upgrade check``
+  Performs a release-specific readiness check before restarting services with
+  new code. For example, missing or changed configuration options,
+  incompatible object states, or other conditions that could lead to
+  failures while upgrading.
+
+  **Return Codes**
+
+  .. list-table::
+     :widths: 20 80
+     :header-rows: 1
+
+     * - Return code
+       - Description
+     * - 0
+       - All upgrade readiness checks passed successfully and there is nothing
+         to do.
+     * - 1
+       - At least one check encountered an issue and requires further
+         investigation. This is considered a warning but the upgrade may be OK.
+     * - 2
+       - There was an upgrade status check failure that needs to be
+         investigated. This should be considered something that stops an
+         upgrade.
+     * - 255
+       - An unexpected error occurred.
+
+  **History of Checks**
+
+  **1.12.0 (Stein)**
+
+  * Sample check to be filled in with checks as they are added in Stein.

lower-constraints.txt

@@ -85,6 +85,7 @@ oslo.policy==1.34.0
 oslo.reports==1.27.0
 oslo.serialization==2.25.0
 oslo.service==1.30.0
+oslo.upgradecheck==0.1.0
 oslo.utils==3.36.0
 oslo.versionedobjects==1.32.0
 oslotest==3.3.0

releasenotes/notes/add-upgrade-check-framework-5bb9693c8a78931c.yaml

@@ -0,0 +1,13 @@
+---
+prelude: >
+    Added new tool ``watcher-status upgrade check``.
+features:
+  - |
+    New framework for ``watcher-status upgrade check`` command is added.
+    This framework allows adding various checks which can be run before a
+    Watcher upgrade to ensure if the upgrade can be performed safely.
+upgrade:
+  - |
+    Operator can now use new CLI tool ``watcher-status upgrade check``
+    to check if Watcher deployment can be safely upgraded from
+    N-1 to N release.

requirements.txt

@@ -22,6 +22,7 @@ oslo.policy>=1.34.0 # Apache-2.0
 oslo.reports>=1.27.0 # Apache-2.0
 oslo.serialization>=2.25.0 # Apache-2.0
 oslo.service>=1.30.0 # Apache-2.0
+oslo.upgradecheck>=0.1.0 # Apache-2.0
 oslo.utils>=3.36.0 # Apache-2.0
 oslo.versionedobjects>=1.32.0 # Apache-2.0
 PasteDeploy>=1.5.2 # MIT

setup.cfg

@@ -44,6 +44,7 @@ console_scripts =
     watcher-decision-engine = watcher.cmd.decisionengine:main
     watcher-applier = watcher.cmd.applier:main
     watcher-sync = watcher.cmd.sync:main
+    watcher-status = watcher.cmd.status:main
 
 watcher.database.migration_backend =
     sqlalchemy = watcher.db.sqlalchemy.migration

watcher/cmd/status.py

@@ -0,0 +1,53 @@
+# Copyright (c) 2018 NEC, Corp.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import sys
+
+from oslo_upgradecheck import upgradecheck
+
+from watcher._i18n import _
+from watcher import conf
+
+CONF = conf.CONF
+
+
+class Checks(upgradecheck.UpgradeCommands):
+
+    """Contains upgrade checks
+
+    Various upgrade checks should be added as separate methods in this class
+    and added to _upgrade_checks tuple.
+    """
+
+    def _sample_check(self):
+        """This is sample check added to test the upgrade check framework
+
+        It needs to be removed after adding any real upgrade check
+        """
+        return upgradecheck.Result(upgradecheck.Code.SUCCESS, 'Sample detail')
+
+    _upgrade_checks = (
+        # Sample check added for now.
+        # Whereas in future real checks must be added here in tuple
+        (_('Sample Check'), _sample_check),
+    )
+
+
+def main():
+    return upgradecheck.main(
+        CONF, project='watcher', upgrade_command=Checks())
+
+
+if __name__ == '__main__':
+    sys.exit(main())

watcher/tests/cmd/test_status.py

@@ -0,0 +1,30 @@
+# Copyright (c) 2018 NEC, Corp.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslo_upgradecheck.upgradecheck import Code
+
+from watcher.cmd import status
+from watcher.tests import base
+
+
+class TestUpgradeChecks(base.TestCase):
+
+    def setUp(self):
+        super(TestUpgradeChecks, self).setUp()
+        self.cmd = status.Checks()
+
+    def test__sample_check(self):
+        check_result = self.cmd._sample_check()
+        self.assertEqual(
+            Code.SUCCESS, check_result.code)