The project support python3.9.

Change-Id: Iab7d9bac7354ef0e5cb990ac25fd17f126bec651

Update gate CI for yoga version

Change-Id: Iaabe5d1c70dcd20e2787d59241268c0013408f64

Add python3.9 UT job for CI

Change-Id: Ib5f202870200fb4e22d4184fac583264c836b457

Add python3.9  CI  job.

Change-Id: I85674c664821aa2370d4f0d6d09657374dfdda7e

Update tox.ini for local test in python3.

Change-Id: I9a3fadb6b6f87ec19e8ca26ee2a3169230efc3ab

Change-Id: I69ea73879d09b14addd2f889b00f0d1156395299

Add lower-constraints gate CI

Change-Id: Ib2c9d67f96d37d5f85377dd41ef1e9378df35465

The error of  tempest test cases for schedule:

ft1.2: freezer_tempest_plugin.tests.scheduler.test_freezer_scheduler.TestFreezerCmdAction.test_freezer_schedulers_restart[gate]testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/opt/stack/tempest/.tox/tempest/lib/python3.8/site-packages/freezer_tempest_plugin/tests/scheduler/test_freezer_scheduler.py", line 33, in test_freezer_schedulers_restart
    self.run_subprocess(args, "Freezer scheduler restart.")
  File "/opt/stack/tempest/.tox/tempest/lib/python3.8/site-packages/freezer_tempest_plugin/tests/scheduler/base.py", line 76, in run_subprocess
    self.assertEqual(0, proc.returncode,
  File "/opt/stack/tempest/.tox/tempest/lib/python3.8/site-packages/testtools/testcase.py", line 415, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/opt/stack/tempest/.tox/tempest/lib/python3.8/site-packages/testtools/testcase.py", line 502, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 0 != 1: Freezer scheduler restart. Output: 2021-06-09 01:05:20.991 116248 CRITICAL freezer-scheduler [-] Unhandled error: OSError: [Errno 88] Socket operation on non-socket
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler Traceback (most recent call last):
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/usr/local/bin/freezer-scheduler", line 10, in <module>
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     sys.exit(main())
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/opt/stack/freezer/freezer/scheduler/freezer_scheduler.py", line 259, in main
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     daemon.restart()
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/opt/stack/freezer/freezer/scheduler/daemon.py", line 204, in restart
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     self.start()
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/opt/stack/freezer/freezer/scheduler/daemon.py", line 178, in start
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     with DaemonContext(pidfile=pidfile, signal_map=self.signal_map,
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/opt/stack/freezer/freezer/lib/pep3143daemon/daemon.py", line 132, in __init__
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     self.detach_process = detach_required()
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/opt/stack/freezer/freezer/lib/pep3143daemon/daemon.py", line 416, in detach_required
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     if parent_is_inet() or parent_is_init():
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/opt/stack/freezer/freezer/lib/pep3143daemon/daemon.py", line 394, in parent_is_inet
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     sock = socket.fromfd(
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/usr/lib/python3.8/socket.py", line 544, in fromfd
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     return socket(family, type, proto, nfd)
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler   File "/usr/lib/python3.8/socket.py", line 231, in __init__
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler     _socket.socket.__init__(self, family, type, proto, fileno)
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler OSError: [Errno 88] Socket operation on non-socket
2021-06-09 01:05:20.991 116248 ERROR freezer-scheduler [00m

Change-Id: I65bb2b620fcc20c3ee3a38cf95cd4280443f77d4

Make the code structure looks more clear and more clean.

Change-Id: I5cfce411d7cc182d3ac50170b2ea6a4bc2598525

Resolves warnings like the following:

  UserWarning: Usage of dash-separated 'description-file' will not be
  supported in future versions. Please use the underscore name
  'description_file' instead

Change-Id: Ib6b5c10bb8e9179619275fd21c35d4e7936baaad

Change-Id: Ia39021e543fea24f686caeacd8dcef964c80f431

Change-Id: Icf6a719bc71d1a478d0a232e65d01a3b6617e7e6

Change-Id: Ifcef7876c3b1930ebd1237e9c1264db8278e332e

Change-Id: I3459d776df233dbe8c36495db3cc113984b44e94

Change-Id: If11616c358681b2363ea5ff37c1aba726e4d9091

Change-Id: I8955f673b968c34b9b27f6e305f17ab3b6fcfac2

Change-Id: I3db2a946d0950c9b01ee8912c43f7704ffd97c5d

Change-Id: I33388d127121cc8e017f9db7209ad03773098929

Change-Id: Iccd20901384ccee82dbb1e57dc6dddf211cbbcd0

Change-Id: I75b4025cb207bb0aa59c4325819add1be45cf08e

Change-Id: I850f92470380de21b91406eda28ca01339b61d43

Change-Id: I1abb4eca21a19ee810cf3017116eaf446b94af8b

Change-Id: Ibf1b42c7c41aacb4f5d5cb8d2699cb069436f230

Change-Id: I4afb36f7b87e5c2150ad8f675eeb397fd2b07b69

Change-Id: I3c2ffda9bc861fab98fe0a8fa5b26a5fd8cef0ff

1. no_voting for lower-constraints CI
2.pep8 create: /home/zuul/src/opendev.org/openstack/freezer/.tox/pep8
pep8 installdeps: -c/home/zuul/src/opendev.org/openstack/requirements/upper-constraints.txt, -r/home/zuul/src/opendev.org/openstack/freezer/test-requirements.txt
ERROR: invocation failed (exit code 1), logfile: /home/zuul/src/opendev.org/openstack/freezer/.tox/pep8/log/pep8-1.log
================================== log start ===================================
Looking in indexes: https://mirror.bhs1.ovh.opendev.org/pypi/simple, https://mirror.bhs1.ovh.opendev.org/wheel/ubuntu-20.04-x86_64
Collecting astroid==2.1.0
  Downloading https://mirror.bhs1.ovh.opendev.org/pypifiles/packages/fc/53/8809bc008bad0300897281a7b320b286dc0e84e836396c0cff6279841e8a/astroid-2.1.0-py3-none-any.whl (176 kB)
Collecting pylint==2.3.1
  Downloading https://mirror.bhs1.ovh.opendev.org/pypifiles/packages/60/c2/b3f73f4ac008bef6e75bca4992f3963b3f85942e0277237721ef1c151f0d/pylint-2.3.1-py3-none-any.whl (765 kB)
INFO: pip is looking at multiple versions of <Python from Requires-Python> to determine which version is compatible with other requirements. This could take a while.
INFO: pip is looking at multiple versions of astroid to determine which version is compatible with other requirements. This could take a while.
ERROR: Cannot install -r /home/zuul/src/opendev.org/openstack/freezer/test-requirements.txt (line 23) and astroid==2.1.0 because these package versions have conflicting dependencies.

The conflict is caused by:
    The user requested astroid==2.1.0
    pylint 2.3.1 depends on astroid<3 and >=2.2.0

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/user_guide/#fixing-conflicting-dependencies
WARNING: You are using pip version 20.3.3; however, version 21.0 is available.
You should consider upgrading via the '/home/zuul/src/opendev.org/openstack/freezer/.tox/pep8/bin/python -m pip install --upgrade pip' command.
================================ log end ===============================

Change-Id: I898d03d716ebc6c6285c4589cd30f7875b0c51d2

Add  test cases for freezer.utils.streaming module

Change-Id: I2aa0aacd96c5c614fc2ef39e70d648c7921c056e

Tox trying to install latest versions for building docs which may
not be supported by stable and lower branches, so should be
restricted by respective version's upper-constraints.txt

Change-Id: I47416c166d07104ddf647cbbdb17525614311673

Update "--restore-abs-pat" to "--restore-abs-path"

Change-Id: Ic27d20b03e3a312e2a332f3893377bb39b3d623b

1. Add  a brief introduction of Freezer
2. Correct "DB Elasticsearch " to "DB"
3. Other small errors.

Change-Id: I0bc6e328dedbd6aa8b3fb5ed4d423ff3a34789e8

Update Freezer doc for new version.

Change-Id: I55b6d1109173a222cd04d37889a56b7dd946cb69