fix parallel tox execution (#1214)

CONTRIBUTING.rst

@@ -19,7 +19,7 @@ Before any pull request can be accepted, you must do the following:
   `tools/.github-cla-signers`_
 * Add or update any `unit tests`_ accordingly
 * Add or update any `integration tests`_ (if applicable)
-* Format code (using black and isort) with `tox -e format`
+* Format code (using black and isort) with `tox -e do_format`
 * Ensure unit tests and linting pass using `tox`_
 * Submit a PR against the `main` branch of the `cloud-init` repository
 

tox.ini

@@ -9,39 +9,52 @@ setenv =
 passenv=
     PYTEST_ADDOPTS
 
-[flake_env]
-envdir = {toxworkdir}/.flake_env
-deps =
-    flake8==3.9.2
-    pylint==2.11.1
-    black==21.12b0
-    isort==5.10.1
-    -r{toxinidir}/test-requirements.txt
-    -r{toxinidir}/integration-requirements.txt
+[format_deps]
+flake8==3.9.2
+pylint==2.11.1
+black==21.12b0
+isort==5.10.1
 
 [testenv:flake8]
-envdir = {[flake_env]envdir}
-deps = {[flake_env]deps}
+deps =
+    flake8=={[format_deps]flake8}
 commands = {envpython} -m flake8 {posargs:cloudinit/ tests/ tools/ setup.py}
 
 [testenv:pylint]
-envdir = {[flake_env]envdir}
-deps = {[flake_env]deps}
+deps =
+    pylint=={[format_deps]pylint}
+    -r{toxinidir}/test-requirements.txt
+    -r{toxinidir}/integration-requirements.txt
 commands = {envpython} -m pylint {posargs:cloudinit tests tools}
 
 [testenv:black]
-envdir = {[flake_env]envdir}
-deps = {[flake_env]deps}
+deps =
+    black=={[format_deps]black}
 commands = {envpython} -m black . --check
 
 [testenv:isort]
-envdir = {[flake_env]envdir}
-deps = {[flake_env]deps}
+deps =
+    isort=={[format_deps]isort}
 commands = {envpython} -m isort . --check-only
 
-[testenv:format]
-envdir = {[flake_env]envdir}
-deps = {[flake_env]deps}
+[testenv:check_format]
+deps =
+    flake8=={[format_deps]flake8}
+    pylint=={[format_deps]pylint}
+    black=={[format_deps]black}
+    isort=={[format_deps]isort}
+    -r{toxinidir}/test-requirements.txt
+    -r{toxinidir}/integration-requirements.txt
+commands =
+    {[testenv:black]commands}
+    {[testenv:isort]commands}
+    {[testenv:flake8]commands}
+    {[testenv:pylint]commands}
+
+[testenv:do_format]
+deps =
+    black=={[format_deps]black}
+    isort=={[format_deps]isort}
 commands =
     {envpython} -m isort .
     {envpython} -m black .