fix: require python 3.7+ (#580)

* chore(python): drop python 3.6

Source-Link: googleapis/synthtool@4f89b13
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:e7bb19d47c13839fe8c147e50e02e8b6cf5da8edd1af8b82208cd6f66cc2829c

* add api_description to .repo-metadata.json

* require python 3.7+ in setup.py

* revert templated README

* remove python 3.6 sample configs

* exclude templated README

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Anthonios Partheniou <[email protected]>

Author: gcf-owl-bot[bot]

.github/.OwlBot.lock.yaml

@@ -13,5 +13,5 @@
 # limitations under the License.
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
-  digest: sha256:b2dc5f80edcf5d4486c39068c9fa11f7f851d9568eea4dcba130f994ea9b5e97
-# created: 2022-06-12T16:09:31.61859086Z
+  digest: sha256:e7bb19d47c13839fe8c147e50e02e8b6cf5da8edd1af8b82208cd6f66cc2829c
+# created: 2022-07-05T18:31:20.838186805Z

.kokoro/samples/python3.6/common.cfg

@@ -33,7 +33,7 @@ export PYTHONUNBUFFERED=1
 env | grep KOKORO
 
 # Install nox
-python3.6 -m pip install --upgrade --quiet nox
+python3.9 -m pip install --upgrade --quiet nox
 
 # Use secrets acessor service account to get secrets
 if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
@@ -76,7 +76,7 @@ for file in samples/**/requirements.txt; do
     echo "------------------------------------------------------------"
 
     # Use nox to execute the tests for the project.
-    python3.6 -m nox -s "$RUN_TESTS_SESSION"
+    python3.9 -m nox -s "$RUN_TESTS_SESSION"
     EXIT=$?
 
     # If this is a periodic build, send the test log to the FlakyBot.

.kokoro/samples/python3.6/continuous.cfg

@@ -12,5 +12,6 @@
     "api_id": "logging.googleapis.com",
     "codeowner_team": "@googleapis/api-logging",
     "default_version": "v2",
-    "api_shortname": "logging"
+    "api_shortname": "logging",
+    "api_description": "allows you to store, search, analyze, monitor, and alert on log data and events from Google Cloud and Amazon Web Services. Using the BindPlane service, you can also collect this data from over 150 common application components, on-premises systems, and hybrid cloud systems. BindPlane is included with your Google Cloud project at no additional cost."
 }

.kokoro/samples/python3.6/periodic-head.cfg

@@ -22,7 +22,7 @@ In order to add a feature:
   documentation.
 
 - The feature must work fully on the following CPython versions:
-  3.6, 3.7, 3.8, 3.9 and 3.10 on both UNIX and Windows.
+  3.7, 3.8, 3.9 and 3.10 on both UNIX and Windows.
 
 - The feature must not add unnecessary dependencies (where
   "unnecessary" is of course subjective, but new dependencies should
@@ -221,13 +221,11 @@ Supported Python Versions
 
 We support:
 
--  `Python 3.6`_
 -  `Python 3.7`_
 -  `Python 3.8`_
 -  `Python 3.9`_
 -  `Python 3.10`_
 
-.. _Python 3.6: https://docs.python.org/3.6/
 .. _Python 3.7: https://docs.python.org/3.7/
 .. _Python 3.8: https://docs.python.org/3.8/
 .. _Python 3.9: https://docs.python.org/3.9/
@@ -239,7 +237,7 @@ Supported versions can be found in our ``noxfile.py`` `config`_.
 .. _config: https://github.com/googleapis/python-logging/blob/main/noxfile.py
 
 
-We also explicitly decided to support Python 3 beginning with version 3.6.
+We also explicitly decided to support Python 3 beginning with version 3.7.
 Reasons for this include:
 
 -  Encouraging use of newest versions of Python 3

.kokoro/samples/python3.6/periodic.cfg

@@ -31,7 +31,7 @@
 
 DEFAULT_PYTHON_VERSION = "3.8"
 
-UNIT_TEST_PYTHON_VERSIONS = ["3.6", "3.7", "3.8", "3.9", "3.10"]
+UNIT_TEST_PYTHON_VERSIONS = ["3.7", "3.8", "3.9", "3.10"]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
     "asyncmock",
@@ -340,28 +340,15 @@ def docfx(session):
 def prerelease_deps(session):
     """Run all tests with prerelease versions of dependencies installed."""
 
-    prerel_deps = [
-        "protobuf",
-        "googleapis-common-protos",
-        "google-auth",
-        "grpcio",
-        "grpcio-status",
-        "google-api-core",
-        "proto-plus",
-        # dependencies of google-auth
-        "cryptography",
-        "pyasn1",
-    ]
-
-    for dep in prerel_deps:
-        session.install("--pre", "--no-deps", "--upgrade", dep)
-
-    # Remaining dependencies
-    other_deps = ["requests"]
-    session.install(*other_deps)
-
+    # Install all dependencies
+    session.install("-e", ".[all, tests, tracing]")
     session.install(*UNIT_TEST_STANDARD_DEPENDENCIES)
-    session.install(*SYSTEM_TEST_STANDARD_DEPENDENCIES)
+    system_deps_all = (
+        SYSTEM_TEST_STANDARD_DEPENDENCIES
+        + SYSTEM_TEST_EXTERNAL_DEPENDENCIES
+        + SYSTEM_TEST_EXTRAS
+    )
+    session.install(*system_deps_all)
 
     # Because we test minimum dependency versions on the minimum Python
     # version, the first version we test with in the unit tests sessions has a
@@ -375,19 +362,44 @@ def prerelease_deps(session):
         constraints_text = constraints_file.read()
 
     # Ignore leading whitespace and comment lines.
-    deps = [
+    constraints_deps = [
         match.group(1)
         for match in re.finditer(
             r"^\s*(\S+)(?===\S+)", constraints_text, flags=re.MULTILINE
         )
     ]
 
-    # Don't overwrite prerelease packages.
-    deps = [dep for dep in deps if dep not in prerel_deps]
-    # We use --no-deps to ensure that pre-release versions aren't overwritten
-    # by the version ranges in setup.py.
-    session.install(*deps)
-    session.install("--no-deps", "-e", ".[all]")
+    session.install(*constraints_deps)
+
+    if os.path.exists("samples/snippets/requirements.txt"):
+        session.install("-r", "samples/snippets/requirements.txt")
+
+    if os.path.exists("samples/snippets/requirements-test.txt"):
+        session.install("-r", "samples/snippets/requirements-test.txt")
+
+    prerel_deps = [
+        "protobuf",
+        # dependency of grpc
+        "six",
+        "googleapis-common-protos",
+        "grpcio",
+        "grpcio-status",
+        "google-api-core",
+        "proto-plus",
+        "google-cloud-testutils",
+        # dependencies of google-cloud-testutils"
+        "click",
+    ]
+
+    for dep in prerel_deps:
+        session.install("--pre", "--no-deps", "--upgrade", dep)
+
+    # Remaining dependencies
+    other_deps = [
+        "requests",
+        "google-auth",
+    ]
+    session.install(*other_deps)
 
     # Print out prerelease package versions
     session.run(
@@ -396,5 +408,16 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
 
     session.run("py.test", "tests/unit")
-    session.run("py.test", "tests/system")
-    session.run("py.test", "samples/snippets")
+
+    system_test_path = os.path.join("tests", "system.py")
+    system_test_folder_path = os.path.join("tests", "system")
+
+    # Only run system tests if found.
+    if os.path.exists(system_test_path) or os.path.exists(system_test_folder_path):
+        session.run("py.test", "tests/system")
+
+    snippets_test_path = os.path.join("samples", "snippets")
+
+    # Only run samples tests if found.
+    if os.path.exists(snippets_test_path):
+        session.run("py.test", "samples/snippets")