Add pre-commit hook for pylint

.pre-commit-config.yaml

@@ -10,6 +10,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+default_language_version:
+  python: python3.7
 repos:
   - repo: https://github.com/pre-commit/mirrors-yapf
     # this rev is a release tag in the repo above and corresponds with a yapf
@@ -18,8 +20,8 @@ repos:
     hooks:
       - id: yapf
         files: ^sdks/python/apache_beam/
-        # keep these in sync with sdks/python/.yapfignore
-        exclude: >
+        # keep these in sync with sdks/python/.yapfignore  and run_pylint.sh
+        exclude: &exclude >
             (?x)^(
                 sdks/python/apache_beam/io/gcp/internal/clients/bigquery/bigquery_v2_client.py|
                 sdks/python/apache_beam/io/gcp/internal/clients/bigquery/bigquery_v2_messages.py|
@@ -30,3 +32,13 @@ repos:
                 sdks/python/apache_beam/coders/proto2_coder_test_messages_pb2.py|
                 sdks/python/apache_beam/portability/api/.*pb2.*.py
             )$
+
+  - repo: https://github.com/pycqa/pylint
+    # this rev is a release tag in the repo above and corresponds with a pylint
+    # version. make sure this matches the version of pylint in tox.ini.
+    rev: pylint-2.4.3
+    hooks:
+      - id: pylint
+        args: ["--rcfile=sdks/python/.pylintrc"]
+        files: ^sdks/python/apache_beam/
+        exclude: *exclude

sdks/python/tox.ini

@@ -185,6 +185,7 @@ commands =
 [testenv:py37-lint]
 # Don't set TMPDIR to avoid "AF_UNIX path too long" errors in pylint.
 setenv =
+# keep the version of pylint in sync with the 'rev' in .pre-commit-config.yaml
 deps =
   -r build-requirements.txt
   astroid<2.4,>=2.3.0