fix: require python 3.7+ (#304)

* 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

* remove python 3.6 sample configs

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* exclude templated readme

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

Author: 3 people

.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:a5d81b61dfd1a432d3c03f51a25d2e71b37be24da509966d50724aea7c57c5c2
-# created: 2022-07-04T12:33:08.125873124Z
+  digest: sha256:e7bb19d47c13839fe8c147e50e02e8b6cf5da8edd1af8b82208cd6f66cc2829c
+# created: 2022-07-05T18:31:20.838186805Z

.github/workflows/unittest.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ['3.6', '3.7', '3.8', '3.9', '3.10']
+        python: ['3.7', '3.8', '3.9', '3.10']
     steps:
     - name: Checkout
       uses: actions/checkout@v3

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

@@ -12,5 +12,6 @@
     "api_id": "compute.googleapis.com",
     "codeowner_team": "@googleapis/api-compute",
     "default_version": "v1",
-    "api_shortname": "compute"
+    "api_shortname": "compute",
+    "api_description": "delivers virtual machines running in Google's innovative data centers and worldwide fiber network. Compute Engine's tooling and workflow support enable scaling from single instances to global, load-balanced cloud computing. Compute Engine's VMs boot quickly, come with persistent disk storage, deliver consistent performance and are available in many configurations."
 }

.kokoro/samples/python3.6/continuous.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-compute/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-head.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",
@@ -331,28 +331,15 @@ 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
@@ -366,19 +353,44 @@ 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(
@@ -387,5 +399,16 @@ 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")