charmcraft build no longer works on xenial (py35) after 0.10.2

[Alex Kavanagh]

Error:

 . Building /var/lib/jenkins/workspace/charm_pusher_ceph-iscsi_master/ceph-iscsi (ceph-iscsi) via tox
build create: /var/lib/jenkins/workspace/charm_pusher_ceph-iscsi_master/ceph-iscsi/.tox/build
build installdeps: -r/var/lib/jenkins/workspace/charm_pusher_ceph-iscsi_master/ceph-iscsi/build-requirements.txt
build installed: appdirs==1.4.4,attrs==21.2.0,certifi==2021.5.30,cffi==1.14.5,chardet==4.0.0,charmcraft==0.10.0.dev0+unknown,humanize==2.6.0,idna==2.10,importlib-metadata==2.1.1,Jinja2==2.11.3,jsonschema==3.2.0,macaroonbakery==1.3.1,MarkupSafe==1.1.1,protobuf==3.17.3,pycparser==2.20,pydantic==0.1,pymacaroons==0.13.0,PyNaCl==1.4.0,pyRFC3339==1.1,pyrsistent==0.17.3,python-dateutil==2.8.1,pytz==2021.1,PyYAML==5.3.1,requests==2.25.1,requests-toolbelt==0.9.1,six==1.16.0,tabulate==0.8.9,urllib3==1.26.5,zipp==1.2.0
build run-test-pre: PYTHONHASHSEED='0'
build run-test: commands[0] | charmcraft build
Traceback (most recent call last):
  File "/var/lib/jenkins/workspace/charm_pusher_ceph-iscsi_master/ceph-iscsi/.tox/build/bin/charmcraft", line 5, in <module>
    from charmcraft.main import main
  File "/var/lib/jenkins/workspace/charm_pusher_ceph-iscsi_master/ceph-iscsi/.tox/build/lib/python3.5/site-packages/charmcraft/main.py", line 24, in <module>
    from charmcraft import helptexts, config
  File "/var/lib/jenkins/workspace/charm_pusher_ceph-iscsi_master/ceph-iscsi/.tox/build/lib/python3.5/site-packages/charmcraft/config.py", line 93
    f"{value!r} must be a valid relative path (cannot be empty)"
                                                               ^
SyntaxError: invalid syntax

Currently the build use the charmcraft python package, and this isn't compatible with py35 which ships with xenial. The jenkins builder is xenial (to build charms that are compatible with xenial).

So either we need to pin charmcraft in the jenkins builder, or snap install the charmcraft package.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-ceph-iscsi/+/795569

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-manila-netapp/+/795574

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-ceph-iscsi/+/795569
Committed: https://opendev.org/openstack/charm-ceph-iscsi/commit/1a234aab38830167efff470dd48d6d5be5e6085f
Submitter: "Zuul (22348)"
Branch: master

commit 1a234aab38830167efff470dd48d6d5be5e6085f
Author: Alex Kavanagh <email address hidden>
Date: Wed Jun 9 16:09:13 2021 +0100

    Pin charmcraft to 0.10.2

    Charmcraft 1.0+ breaks py35 compatibility by introducing f-strings. As
    the charms are still being built on a xenial builder, we currently need
    to pin this for the builds.

    Close-bug: #1931436
    Change-Id: I88f1a2ef629db4bd3add8c346b946b66cf3b08ed

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-manila-netapp/+/795574
Committed: https://opendev.org/openstack/charm-manila-netapp/commit/b389284722134f34ca56c10ed895c63a310d2043
Submitter: "Zuul (22348)"
Branch: master

commit b389284722134f34ca56c10ed895c63a310d2043
Author: Alex Kavanagh <email address hidden>
Date: Wed Jun 9 16:23:46 2021 +0100

    Pin charmcraft to 0.10.2

    Charmcraft 1.0+ breaks py35 compatibility by introducing f-strings. As
    the charms are still being built on a xenial builder, we currently need
    to pin this for the builds.

    Close-bug: #1931436
    Change-Id: I405d6a36a3299943baeaf7c216bda57eb1ec5f21