diff --git a/src/files/.gitkeep b/src/files/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/src/test-requirements.txt b/src/test-requirements.txt
index e56db9a..a4b77a5 100644
--- a/src/test-requirements.txt
+++ b/src/test-requirements.txt
@@ -15,7 +15,7 @@ aodhclient>=0.1.0
 gnocchiclient>=3.1.0,<3.2.0
 python-barbicanclient>=4.0.1
 python-ceilometerclient>=1.5.0
-python-cinderclient>=1.4.0
+python-cinderclient>=1.4.0,<5.0.0
 python-designateclient>=1.5
 python-glanceclient>=1.1.0
 python-heatclient>=0.8.0
diff --git a/src/tox.ini b/src/tox.ini
index 4c5f90e..8a91d50 100644
--- a/src/tox.ini
+++ b/src/tox.ini
@@ -1,49 +1,51 @@
-# Source charm: ./src/tox.ini
+# Source charm (with amulet): ./src/tox.ini
 # This file is managed centrally by release-tools and should not be modified
-# within individual charm repos.
+# 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
+
 [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
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
+         CHARM_DIR={envdir}
          AMULET_SETUP_TIMEOUT=5400
 whitelist_externals = juju
-passenv = HOME TERM AMULET_* CS_*
+passenv = HOME TERM AMULET_* CS_* OS_* TEST_*
 deps = -r{toxinidir}/test-requirements.txt
 install_command =
   pip install {opts} {packages}
 
 [testenv:pep8]
-basepython = python2.7
+basepython = python3
 commands = charm-proof
 
-[testenv:func27-noop]
+[testenv:func-noop]
 # DRY RUN - For Debug
 basepython = python2.7
 commands =
     bundletester -vl DEBUG -r json -o func-results.json --test-pattern "gate-*" -n --no-destroy
 
-[testenv:func27]
+[testenv:func]
 # Run all gate tests which are +x (expected to always pass)
 basepython = python2.7
 commands =
     bundletester -vl DEBUG -r json -o func-results.json --test-pattern "gate-*" --no-destroy
 
-[testenv:func27-smoke]
+[testenv:func-smoke]
 # Run a specific test as an Amulet smoke test (expected to always pass)
 basepython = python2.7
 commands =
     bundletester -vl DEBUG -r json -o func-results.json gate-basic-bionic-stein --no-destroy
 
-[testenv:func27-dfs]
-# Run all deploy-from-source tests which are +x (may not always pass!)
-basepython = python2.7
-commands =
-    bundletester -vl DEBUG -r json -o func-results.json --test-pattern "dfs-*" --no-destroy
-
-[testenv:func27-dev]
+[testenv:func-dev]
 # Run all development test targets which are +x (may not always pass!)
 basepython = python2.7
 commands =
diff --git a/tox.ini b/tox.ini
index 8cb53db..5b41c1d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,16 @@
 # Source charm: ./tox.ini
 # This file is managed centrally by release-tools and should not be modified
-# within individual charm repos.
+# 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
+
 [tox]
 skipsdist = True
-envlist = pep8,py37
-skip_missing_interpreters = 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
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
@@ -13,39 +19,36 @@ setenv = VIRTUAL_ENV={envdir}
          LAYER_PATH={toxinidir}/layers
          INTERFACE_PATH={toxinidir}/interfaces
          JUJU_REPOSITORY={toxinidir}/build
-passenv = http_proxy https_proxy
+passenv = http_proxy https_proxy INTERFACE_PATH LAYER_PATH JUJU_REPOSITORY
 install_command =
   pip install {opts} {packages}
 deps =
     -r{toxinidir}/requirements.txt
 
 [testenv:build]
-basepython = python2.7
+basepython = python3
 commands =
     charm-build --log-level DEBUG -o {toxinidir}/build src {posargs}
 
-[testenv:py27]
-basepython = python2.7
-# Reactive source charms are Python3-only, but a py27 unit test target
-# is required by OpenStack Governance.  Remove this shim as soon as
-# permitted.  http://governance.openstack.org/reference/cti/python_cti.html
-whitelist_externals = true
-commands = true
-
-[testenv:py34]
-basepython = python3.4
+[testenv:py3]
+basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
-commands = stestr run {posargs}
+commands = stestr run --slowest {posargs}
+
+[testenv:py35]
+basepython = python3.5
+deps = -r{toxinidir}/test-requirements.txt
+commands = stestr run --slowest {posargs}
 
 [testenv:py36]
 basepython = python3.6
 deps = -r{toxinidir}/test-requirements.txt
-commands = stestr run {posargs}
+commands = stestr run --slowest {posargs}
 
 [testenv:py37]
 basepython = python3.7
 deps = -r{toxinidir}/test-requirements.txt
-commands = stestr run {posargs}
+commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
 basepython = python3
@@ -56,13 +59,14 @@ commands = flake8 {posargs} src unit_tests
 # Technique based heavily upon
 # https://github.com/openstack/nova/blob/master/tox.ini
 basepython = python3
-deps = -r{toxinidir}/test-requirements.txt
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run
 commands =
     coverage erase
-    stestr run {posargs}
+    stestr run --slowest {posargs}
     coverage combine
     coverage html -d cover
     coverage xml -o cover/coverage.xml
@@ -85,4 +89,4 @@ commands = {posargs}
 
 [flake8]
 # E402 ignore necessary for path append before sys module import in actions
-ignore = E402
+ignore = E402,W504