Remove the openstack-upgrade action

The openstack-principle reactive layer brings both the
openstack-origin option and the openstack-upgrade
action, none of which being needed for this charm.
This layer has been used already since the very first
commit of this charm, most likely for no specific
reason.

Also synced tox/pip boilerplate in order to include:
* https://github.com/openstack-charmers/release-tools/pull/156
* https://github.com/openstack-charmers/release-tools/pull/157

Closes-Bug: #1944953
Change-Id: I001f435c648229b65fb718a78a33e6303a0faf11

.zuul.yaml

@@ -1,5 +1,4 @@
 - project:
     templates:
-      - python35-charm-jobs
-      - openstack-python3-ussuri-jobs
+      - openstack-python3-charm-jobs
       - openstack-cover-jobs

pip.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+#
+# This file is managed centrally by release-tools and should not be modified
+# within individual charm repos.  See the 'global' dir contents for available
+# choices of tox.ini for OpenStack Charms:
+#     https://github.com/openstack-charmers/release-tools
+#
+# setuptools 58.0 dropped the support for use_2to3=true which is needed to
+# install blessings (an indirect dependency of charm-tools).
+#
+# More details on the beahvior of tox and virtualenv creation can be found at
+# https://github.com/tox-dev/tox/issues/448
+#
+# This script is wrapper to force the use of the pinned versions early in the
+# process when the virtualenv was created and upgraded before installing the
+# depedencies declared in the target.
+pip install 'pip<20.3' 'setuptools<50.0.0'
+pip "$@"

src/layer.yaml

@@ -2,7 +2,7 @@ includes:
   - layer:coordinator
   - layer:leadership
   - layer:snap
-  - layer:openstack-principle
+  - layer:openstack
   - interface:mysql-shared
   - interface:mysql-router
   - interface:mysql-innodb-cluster
@@ -20,7 +20,6 @@ repo: https://opendev.org/openstack/charm-mysql-innodb-cluster
 config:
   deletes:
     - verbose
-    - openstack-origin
     - use-internal-endpoints
     - debug
     - use-syslog

src/tox.ini

@@ -22,12 +22,12 @@ skip_missing_interpreters = False
 requires = pip < 20.3
            virtualenv < 20.0
 # NOTE: https://wiki.canonical.com/engineering/OpenStack/InstallLatestToxOnOsci
-minversion = 3.2.0
+minversion = 3.18.0
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
-whitelist_externals = juju
+allowlist_externals = juju
 passenv = HOME TERM CS_* OS_* TEST_*
 deps = -r{toxinidir}/test-requirements.txt
 install_command =

tox.ini

@@ -11,6 +11,21 @@ envlist = pep8,py3
 sitepackages = False
 # NOTE: Avoid false positives by not skipping missing interpreters.
 skip_missing_interpreters = False
+# NOTES:
+# * We avoid the new dependency resolver by pinning pip < 20.3, see
+#   https://github.com/pypa/pip/issues/9187
+# * Pinning dependencies requires tox >= 3.2.0, see
+#   https://tox.readthedocs.io/en/latest/config.html#conf-requires
+# * It is also necessary to pin virtualenv as a newer virtualenv would still
+#   lead to fetching the latest pip in the func* tox targets, see
+#   https://stackoverflow.com/a/38133283
+requires =
+  pip < 20.3
+  virtualenv < 20.0
+  setuptools<50.0.0
+
+# NOTE: https://wiki.canonical.com/engineering/OpenStack/InstallLatestToxOnOsci
+minversion = 3.18.0
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
@@ -21,7 +36,7 @@ setenv = VIRTUAL_ENV={envdir}
          JUJU_REPOSITORY={toxinidir}/build
 passenv = http_proxy https_proxy INTERFACE_PATH LAYER_PATH JUJU_REPOSITORY
 install_command =
-  pip install {opts} {packages}
+  {toxinidir}/pip.sh install {opts} {packages}
 deps =
     -r{toxinidir}/requirements.txt