Implement scaffolding for upgrade checks

One of the community goals for Stein is to implement a command-line
tool for operators that runs programmable checks that might impact
upgradability.

This commit lays down the basic structure for the upgrade checks and
ties it up to `glance-status` command.

Change-Id: I7fcf5235a76d15dbcb2c49255bc26c2b586cd71c
Story: 2003657
Task: 26135

doc/source/cli/glancestatus.rst

@@ -0,0 +1,95 @@
+=============
+glance-status
+=============
+
+---------------------
+Glance Status Utility
+---------------------
+
+.. include:: header.txt
+
+SYNOPSIS
+========
+
+::
+
+  glance-status [options]
+
+DESCRIPTION
+===========
+
+``glance-status`` is a command line utility to aid operators in upgrading
+glance by running programmable checks for things that might prevent upgrades.
+
+COMMANDS
+========
+
+``upgrade``
+      This is the prefix for checking the glance deployment for any upgrade
+      issues that might prevent glance from upgrading.
+
+You can also run with a category argument such as ``upgrade`` to see a list of
+all commands in that category::
+
+    glance-status upgrade
+
+These sections describe the available categories and arguments for
+:command:`glance-status`.
+
+Categories and commands
+-----------------------
+
+``glance-status upgrade check``
+  Performs a release-specific readiness check before restarting services with
+  new code, or upgrading. This command expects to have complete configuration
+  and access to the database.
+
+  **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**
+
+  **18.0.0 (Stein)**
+
+  * Placeholder to be filled in with checks as they are added in Stein.
+
+OPTIONS
+=======
+
+**General Options**
+
+``-h, --help``
+      show this help message and exit
+
+``--config-dir DIR``
+      Path to a config directory to pull `*.conf` files from.
+      This file set is sorted, so as to provide a predictable
+      parse order if individual options are over-ridden. The
+      set is parsed after the file(s) specified via previous
+      --config-file, arguments hence over-ridden options in
+      the directory take precedence.
+
+``--config-file PATH``
+      Path to a config file to use. Multiple config files can
+      be specified, with values in later files taking
+      precedence. Defaults to None.
+
+.. include:: footer.txt

glance/cmd/status.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+
+# 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_config import cfg
+from oslo_upgradecheck import upgradecheck
+
+CONF = cfg.CONF
+
+
+class Checks(upgradecheck.UpgradeCommands):
+    """Programmable upgrade checks."""
+
+    pass
+
+
+def main():
+    return upgradecheck.main(CONF, 'glance', Checks())

lower-constraints.txt

@@ -73,6 +73,7 @@ oslo.middleware==3.31.0
 oslo.policy==1.30.0
 oslo.serialization==2.25.0
 oslo.service==1.30.0
+oslo.upgradecheck==0.1.0
 oslo.utils==3.33.0
 oslotest==3.2.0
 osprofiler==1.4.0

releasenotes/notes/bp-upgrade-checks-b3272c3ddb4e8cf7.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    [`Community Goal <https://governance.openstack.org/tc/goals/stein/upgrade-checkers.html>`_]
+    Support has been added for developers to write pre-upgrade checks.
+    Operators can run these checks using ``glance-status upgrade check``.
+    This allows operators to be more confident when upgrading their deployments
+    by having a tool that automates programmable checks against the deployment
+    configuration or dataset.

requirements.txt

@@ -18,6 +18,7 @@ httplib2>=0.9.1 # MIT
 oslo.config>=5.2.0 # Apache-2.0
 oslo.concurrency>=3.26.0 # Apache-2.0
 oslo.context>=2.19.2 # Apache-2.0
+oslo.upgradecheck>=0.1.0 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 stevedore>=1.20.0 # Apache-2.0
 futurist>=1.2.0 # Apache-2.0

setup.cfg

@@ -43,6 +43,7 @@ console_scripts =
     glance-registry = glance.cmd.registry:main
     glance-replicator = glance.cmd.replicator:main
     glance-scrubber = glance.cmd.scrubber:main
+    glance-status = glance.cmd.status:main
 wsgi_scripts =
     glance-wsgi-api = glance.common.wsgi_app:init_app
 glance.common.image_location_strategy.modules =