Add pre-commit hook

First pass at adding a pre-commit hook to enforce
formatting and linting standards.

This adds the pre-commit command to run on a
limited set of directories. Subsequent changes
will remove excluded folders and run formatting on
them as well.

The command will use the standard pre-commit hooks
for yaml, whitespace, and end of line linting.

It will also use `ruff` configured identically to
the Python SDK repositories.

The intention is to start enforcing formatting and
linting standards on edited code. Running the
pre-commit hook manually will make numerous
changes that should be broken into multiple
phases.

.pre-commit-config.yaml

@@ -0,0 +1,29 @@
+exclude: "\
+    ^(\
+    .changes|\
+    .github|\
+    awscli/examples|\
+    awscli/topics|\
+    awscli/botocore|\
+    awscli/s3transfer|\
+    awscli/doc|\
+    exe/assets|\
+    tests/functional/cloudformation/deploy_templates/booleans/input.yml|\
+    tests/functional/cloudformation/deploy_templates/nested-tag/input.yml|\
+    tests/|\
+    CHANGELOG.rst|\
+    configure\
+    )"
+repos:
+  - repo: 'https://github.com/pre-commit/pre-commit-hooks'
+    rev: v4.5.0
+    hooks:
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.4.8
+    hooks:
+      - id: ruff
+        args: [ --fix ]
+      - id: ruff-format

CONTRIBUTING.rst

@@ -67,7 +67,7 @@ Also, ensure your commit messages match this format::
     Describe your changes in the imperative mood, e.g.
     "Add foo to bar", "Update foo component for bar",
     "Fix race condition for foo".
-    
+
     The body of the commit message can include:
 
     * an explanation of the problem and what this change
@@ -120,6 +120,28 @@ can run these commands::
 When you push to your remote, the output will contain a URL you
 can use to open a pull request.
 
+Codestyle
+---------
+This project uses `ruff <https://github.com/astral-sh/ruff>`__ to enforce
+codstyle requirements. We've codified this process using a tool called
+`pre-commit <https://pre-commit.com/>`__. pre-commit allows us to specify a
+config file with all tools required for code linting, and surfaces either a
+git commit hook, or single command, for enforcing these.
+
+To validate your pull request prior to publishing, you can use the following
+`installation guide <https://pre-commit.com/#install>`__ to setup pre-commit.
+
+If you don't want to use the git commit hook, you can run the below command
+to automatically perform the codestyle validation:
+
+.. code-block:: bash
+
+    $ pre-commit run
+
+This will automatically perform simple updates (such as white space clean up)
+and provide a list of any failing checks. After these are addressed,
+you can commit the changes prior to publishing the pull request.
+
 
 Reporting Issues
 ----------------

pyproject.toml

@@ -130,3 +130,28 @@ markers = [
 
 [tool.black]
 line-length = 80
+
+[tool.ruff.lint]
+# Enable Pyflakes (`F`) and a subset of the pycodestyle (`E`)  codes by default.
+# Unlike Flake8, Ruff doesn't enable pycodestyle warnings (`W`) or
+# McCabe complexity (`C901`) by default.
+select = ["E4", "E7", "E9", "F", "I", "UP"]
+ignore = []
+
+# Allow fix for all enabled rules (when `--fix`) is provided.
+fixable = ["ALL"]
+unfixable = []
+
+# Allow unused variables when underscore-prefixed.
+dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+
+[tool.ruff.format]
+# Like Black, use double quotes for strings, spaces for indents
+# and trailing commas.
+quote-style = "preserve"
+indent-style = "space"
+skip-magic-trailing-comma = false
+line-ending = "auto"
+
+docstring-code-format = false
+docstring-code-line-length = "dynamic"