Fix charm for tox4 compatibility

Related-Bug: 2002788
Change-Id: I3b662aa9c3026e85d088350d969e743a116401a4

build-requirements.txt

@@ -1,7 +0,0 @@
-# NOTES(lourot):
-# * We don't install charmcraft via pip anymore because it anyway spins up a
-#   container and scp the system's charmcraft snap inside it. So the charmcraft
-#   snap is necessary on the system anyway.
-# * `tox -e build` successfully validated with charmcraft 1.2.1
-
-cffi==1.14.6; python_version < '3.6'  # cffi 1.15.0 drops support for py35.

charmcraft.yaml

@@ -2,6 +2,9 @@ type: charm
 
 parts:
   charm:
+    plugin: reactive
+    reactive-charm-build-arguments:
+      - --binary-wheels-from-source
     build-packages:
       - tox
       - git
@@ -10,26 +13,12 @@ parts:
       - libssl-dev
       - rustc
       - cargo
+    source: src/
+    build-snaps:
+      - charm/latest/edge
     build-environment:
-      - MAKEFLAGS: -j$(nproc)
-      - CHARM_INTERFACES_DIR: /root/project/interfaces/
-      - CHARM_LAYERS_DIR: /root/project/layers/
-    override-build: |
-      apt-get install ca-certificates -y
-      tox -e build-reactive
-    override-stage: |
-      echo "Copying charm to staging area: $CRAFT_STAGE"
-      NAME=$(ls $CRAFT_PART_BUILD/build/builds)
-      cp -r $CRAFT_PART_BUILD/build/builds/$NAME/* $CRAFT_STAGE/
-    override-prime: |
-      # For some reason, the normal priming chokes on the fact that there's a
-      # hooks directory.
-      cp -r $CRAFT_STAGE/* .
-      # Charmcraft looks for this specific entry point.
-      mkdir -p src
-      touch src/charm.py
-      chmod +x src/charm.py
-
+      - CHARM_INTERFACES_DIR: $CRAFT_PROJECT_DIR/interfaces/
+      - CHARM_LAYERS_DIR: $CRAFT_PROJECT_DIR/layers/
 bases:
   - build-on:
       - name: ubuntu

osci.yaml

@@ -6,4 +6,4 @@
       needs_charm_build: true
       charm_build_name: barbican
       build_type: charmcraft
-      charmcraft_channel: 2.0/stable
+      charmcraft_channel: 2.1/stable

pip.sh

@@ -1,18 +0,0 @@
-#!/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 "$@"

rename.sh

@@ -1,13 +0,0 @@
-#!/bin/bash
-charm=$(grep "charm_build_name" osci.yaml | awk '{print $2}')
-echo "renaming ${charm}_*.charm to ${charm}.charm"
-echo -n "pwd: "
-pwd
-ls -al
-echo "Removing bad downloaded charm maybe?"
-if [[ -e "${charm}.charm" ]];
-then
-    rm "${charm}.charm"
-fi
-echo "Renaming charm here."
-mv ${charm}_*.charm ${charm}.charm

src/test-requirements.txt

@@ -4,9 +4,6 @@
 #     https://github.com/openstack-charmers/release-tools
 #
 
-# Need tox to be available from tox... inception yes, but its a workaround for now
-tox
-
 # Functional Test Requirements (let Zaza's dependencies solve all dependencies here!)
 git+https://github.com/openstack-charmers/zaza.git#egg=zaza
 git+https://github.com/openstack-charmers/zaza-openstack-tests.git#egg=zaza.openstack

src/tox.ini

@@ -6,32 +6,26 @@
 
 [tox]
 envlist = pep8
-skipsdist = True
 # NOTE: Avoid build/test env pollution by not enabling sitepackages.
 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
-# NOTE: https://wiki.canonical.com/engineering/OpenStack/InstallLatestToxOnOsci
-minversion = 3.18.0
 
 [testenv]
+# We use tox mainly for virtual environment management for test requirements
+# and do not install the charm code as a Python package into that environment.
+# Ref: https://tox.wiki/en/latest/config.html#skip_install
+skip_install = True
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
 allowlist_externals = juju
-passenv = HOME TERM CS_* OS_* TEST_*
+passenv =
+    HOME
+    TERM
+    CS_*
+    OS_*
+    TEST_*
 deps = -r{toxinidir}/test-requirements.txt
-install_command =
-  pip install {opts} {packages}
 
 [testenv:pep8]
 basepython = python3

tox.ini

@@ -5,26 +5,30 @@
 #     https://github.com/openstack-charmers/release-tools
 
 [tox]
-skipsdist = True
 envlist = pep8,py3
 # NOTE: Avoid build/test env pollution by not enabling sitepackages.
 sitepackages = False
 # NOTE: Avoid false positives by not skipping missing interpreters.
 skip_missing_interpreters = False
 
-# NOTE: https://wiki.canonical.com/engineering/OpenStack/InstallLatestToxOnOsci
-minversion = 3.18.0
-
 [testenv]
+# We use tox mainly for virtual environment management for test requirements
+# and do not install the charm code as a Python package into that environment.
+# Ref: https://tox.wiki/en/latest/config.html#skip_install
+skip_install = True
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
          TERM=linux
+         CHARM_LAYERS_DIR={toxinidir}/layers
+         CHARM_INTERFACES_DIR={toxinidir}/interfaces
          JUJU_REPOSITORY={toxinidir}/build
-passenv = no_proxy http_proxy https_proxy JUJU_REPOSITORY
-# We can stop using pip.sh when charmcraft snap includes new version of git:
-# https://github.com/canonical/charmcraft/issues/875
-install_command =
-  {toxinidir}/pip.sh install {opts} {packages}
+passenv =
+    no_proxy
+    http_proxy
+    https_proxy
+    CHARM_INTERFACES_DIR
+    CHARM_LAYERS_DIR
+    JUJU_REPOSITORY
 allowlist_externals =
     charmcraft
     bash
@@ -34,10 +38,14 @@ deps =
 
 [testenv:build]
 basepython = python3
-deps = -r{toxinidir}/build-requirements.txt
+# charmcraft clean is done to ensure that
+# `tox -e build` always performs a clean, repeatable build.
+# For faster rebuilds during development,
+# directly run `charmcraft -v pack && ./rename.sh`.
 commands =
     charmcraft clean
     charmcraft -v pack
+    charmcraft clean
 
 [testenv:build-reactive]
 basepython = python3
@@ -65,18 +73,6 @@ deps = flake8==3.9.2
        git+https://github.com/juju/charm-tools.git
 commands = flake8 {posargs} src unit_tests
 
-[testenv:func-target]
-# Hack to get functional tests working in the charmcraft
-# world. We should fix this.
-basepython = python3
-passenv = HOME TERM CS_* OS_* TEST_*
-deps = -r{toxinidir}/src/test-requirements.txt
-changedir = {toxinidir}/src
-commands =
-  bash -c "if [ ! -f ../*.charm ]; then echo 'Charm does not exist. Run tox -e build'; exit 1; fi"
-  tox --version
-  tox -e func-target {posargs}
-
 [testenv:cover]
 # Technique based heavily upon
 # https://github.com/openstack/nova/blob/master/tox.ini