Add ruff for linting and code quality checks

Replace pyupgrade with ruff in the pre-commit configuration and add
ruff configuration to pyproject.toml.

Ruff is configured to enforce:
- McCabe complexity checking (max complexity: 25)
- Pyflakes rules (unused imports, undefined names, etc.)
- Selected pycodestyle rules (imports, line length)
- 79 character line length (OpenStack standard)
- Python 3.10+ as the target version

Fix lambda assignment in ceilometer/polling/manager.py to comply with
ruff's E731 rule (do not assign a lambda expression, use a def).

Change-Id: I897d03cd42d0eb7c92384e363ac25fcae838ada4
Signed-off-by: Emma Foley <efoley@redhat.com>

.pre-commit-config.yaml

@@ -32,11 +32,6 @@ repos:
     rev: v2.0.0
     hooks:
       - id: doc8
-  - repo: https://github.com/asottile/pyupgrade
-    rev: v3.20.0
-    hooks:
-      - id: pyupgrade
-        args: [--py310-plus]
   - repo: https://github.com/openstack/bashate
     rev: 2.1.1
     hooks:
@@ -48,3 +43,11 @@ repos:
     hooks:
       - id: codespell
         args: ['--ignore-words=doc/dictionary.txt']
+
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.15.7
+    hooks:
+      - id: ruff-check
+        args: ['--fix', '--unsafe-fixes', '--show-fixes'] #--diff']
+      # Add this after submitting a commit for ruff check, then one that fixes linting, then one to move autopep to after this.
+      #- id: ruff-format

ceilometer/polling/manager.py

@@ -203,7 +203,8 @@ class PollingTask:
 
         # we relate the static resources and per-source discovery to
         # each combination of pollster and matching source
-        resource_factory = lambda: Resources(agent_manager)  # noqa: E731
+        def resource_factory():
+            return Resources(agent_manager)
         self.resources = collections.defaultdict(resource_factory)
 
         conf = self.manager.conf

pyproject.toml

@@ -12,3 +12,48 @@ ignore = ["E731"]
 skip = "*.po,*.js,*.css,*.html,*.svg,HACKING.py,*hacking*,*build*,*_static*,doc/dictionary.txt,*.pyc,*.inv,*.gz,*.jpg,*.png,*.vsd,*.graffle,*.json,*telemetry-measurements.rst"
 count = true
 quiet-level = 4
+
+[tool.ruff]
+line-length = 79
+target-version = "py310"
+
+[tool.ruff.lint]
+select = [
+    # mcabe complexity checks
+    "C90",
+    # multiple-imports-on-one-line, module-import-not-at-top-of-file
+    "E4",
+    # line-too-long, redundant-backslash
+    "E5",
+    "E7",
+    "E9",
+    # pyflakes
+    "F",
+    "W",
+]
+external = ["H"]
+ignore = [
+    # we only use asserts for type narrowing
+    "S101",
+    # we do not use random number geneerators for crypto
+    "S311",
+    # S104 Possible binding to all interfaces
+    "S104",
+    # S105 Possible hardcoded password assigned to variable"
+    "S105",
+    # S106 Possible hardcoded password assigned to argument
+    "S106",
+    # S110 `try`-`except`-`pass` detected, consider logging the exception
+    "S110",
+    # UP031 % format — defer f-string migration to a later pass
+    "UP031",
+    # UP032 f-string — defer migration to a later pass
+    "UP032",
+]
+
+[tool.ruff.lint.per-file-ignores]
+"doc/*" = ["E501"]
+
+[tool.ruff.lint.mccabe]
+# Flag errors (`C901`) whenever the complexity level exceeds 25.
+max-complexity = 25

tox.ini

@@ -83,6 +83,7 @@ ignore-path = .venv,.git,.tox,.eggs,*ceilometer/locale*,*lib/python*,ceilometer.
 # W503 line break before binary operator
 # W504 line break after binary operator
 ignore = E123,W503,W504
+select = H
 exclude=.venv,.git,.tox,.eggs,dist,doc,*lib/python*,*egg,build,install-guide
 # [H106] Do not put vim configuration in source files.
 # [H203] Use assertIs(Not)None to check for None.