diff --git a/build-requirements.txt b/build-requirements.txt
deleted file mode 100644
index b6d2452..0000000
--- a/build-requirements.txt
+++ /dev/null
@@ -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.
diff --git a/osci.yaml b/osci.yaml
index 72bc8df..7c97346 100644
--- a/osci.yaml
+++ b/osci.yaml
@@ -6,4 +6,4 @@
       needs_charm_build: true
       charm_build_name: manila-generic
       build_type: charmcraft
-      charmcraft_channel: 2.0/stable
+      charmcraft_channel: 2.1/stable
diff --git a/pip.sh b/pip.sh
deleted file mode 100755
index 9a7e6b0..0000000
--- a/pip.sh
+++ /dev/null
@@ -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 "$@"
diff --git a/src/test-requirements.txt b/src/test-requirements.txt
index 9c7afb7..e771023 100644
--- a/src/test-requirements.txt
+++ b/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
diff --git a/src/tests/bundles/jammy-yoga.yaml b/src/tests/bundles/jammy-yoga.yaml
index 2e9eea4..567f646 100644
--- a/src/tests/bundles/jammy-yoga.yaml
+++ b/src/tests/bundles/jammy-yoga.yaml
@@ -54,8 +54,6 @@ services:
   rabbitmq-server:
     charm: ch:rabbitmq-server
     num_units: 1
-    options:
-      source: *openstack-origin
     to:
       - '4'
     channel: latest/edge
diff --git a/src/tests/bundles/jammy-zed.yaml b/src/tests/bundles/jammy-zed.yaml
index f93953f..00a27ed 100644
--- a/src/tests/bundles/jammy-zed.yaml
+++ b/src/tests/bundles/jammy-zed.yaml
@@ -56,8 +56,6 @@ services:
   rabbitmq-server:
     charm: ch:rabbitmq-server
     num_units: 1
-    options:
-      source: *openstack-origin
     to:
       - '4'
     channel: latest/edge
diff --git a/src/tests/bundles/kinetic-zed.yaml b/src/tests/bundles/kinetic-zed.yaml
index 8f1756b..32c7879 100644
--- a/src/tests/bundles/kinetic-zed.yaml
+++ b/src/tests/bundles/kinetic-zed.yaml
@@ -54,8 +54,6 @@ services:
   rabbitmq-server:
     charm: ch:rabbitmq-server
     num_units: 1
-    options:
-      source: *openstack-origin
     to:
       - '4'
     channel: latest/edge
diff --git a/src/tox.ini b/src/tox.ini
index b40d295..8ffff0f 100644
--- a/src/tox.ini
+++ b/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
diff --git a/tox.ini b/tox.ini
index bdde110..854d8be 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,36 +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
-# 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]
+# 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
-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
@@ -45,11 +39,15 @@ 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
     {toxinidir}/rename.sh
+    charmcraft clean
 
 [testenv:build-reactive]
 basepython = python3
@@ -77,18 +75,6 @@ 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