Dropped support for Python < 3.7 (#9480)

* Drop Python versions <3.7.

* Updated README to clarify that Python 3.7 is the minimum.

* Removed more Python 3.5-specific code.

Also changed tests to skip missing interpreters.

* Invoke tox directly instead of through Python.

Hopefully this will pick up python3.

* Updated java_stretch image to bullseye to get Python >= 3.7.

* Use jdk11 instead of jdk8.

* Installed python2 for gtest.

* Use "python3 -m venv" instead of "virtualenv."

* Install python3-venv.

kokoro/linux/dockerfile/test/java_stretch/Dockerfile

@@ -1,4 +1,7 @@
-FROM debian:stretch
+# Despite the name of this image, we are no longer on stretch.
+# We should consider renaming this image, and/or evaluating what
+# software versions we actually need.
+FROM debian:bullseye
 
 # Install dependencies.  We start with the basic ones required to build protoc
 # and the C++ build
@@ -22,9 +25,11 @@ RUN apt-get update && apt-get install -y \
   wget \
   # Java dependencies
   maven \
-  openjdk-8-jdk \
+  openjdk-11-jdk \
+  # Required for the gtest build.
+  python2 \
   # Python dependencies
   python3-setuptools \
   python3-pip \
-  virtualenv \
+  python3-venv \
   && apt-get clean

kokoro/release/python/windows/build_artifacts.bat

@@ -40,16 +40,6 @@ mkdir %ARTIFACT_DIR%
 
 REM Build wheel
 
-SET PYTHON=C:\python36_32bit
-SET PYTHON_VERSION=3.6
-SET PYTHON_ARCH=32
-CALL build_single_artifact.bat || goto :error
-
-SET PYTHON=C:\python36
-SET PYTHON_VERSION=3.6
-SET PYTHON_ARCH=64
-CALL build_single_artifact.bat || goto :error
-
 SET PYTHON=C:\python37_32bit
 SET PYTHON_VERSION=3.7
 SET PYTHON_ARCH=32

kokoro/release/python/windows/build_single_artifact.bat

@@ -1,11 +1,5 @@
 setlocal
 
-if %PYTHON%==C:\python36_32bit set generator=Visual Studio 14
-if %PYTHON%==C:\python36_32bit set vcplatform=Win32
-
-if %PYTHON%==C:\python36 set generator=Visual Studio 14 Win64
-if %PYTHON%==C:\python36 set vcplatform=x64
-
 if %PYTHON%==C:\python37_32bit set generator=Visual Studio 14
 if %PYTHON%==C:\python37_32bit set vcplatform=Win32
 

python/README.md

@@ -26,7 +26,7 @@ use python c++ implementation.
 Installation
 ============
 
-1) Make sure you have Python 3.5 or newer.  If in doubt, run:
+1) Make sure you have Python 3.7 or newer.  If in doubt, run:
 
        $ python -V
 

python/setup.py

@@ -301,8 +301,6 @@ def get_option_from_sys_argv(option_str):
       classifiers=[
           "Programming Language :: Python",
           "Programming Language :: Python :: 3",
-          "Programming Language :: Python :: 3.5",
-          "Programming Language :: Python :: 3.6",
           "Programming Language :: Python :: 3.7",
           "Programming Language :: Python :: 3.8",
           "Programming Language :: Python :: 3.9",
@@ -323,5 +321,5 @@ def get_option_from_sys_argv(option_str):
       },
       install_requires=install_requires,
       ext_modules=ext_module_list,
-      python_requires=">=3.5",
+      python_requires=">=3.7",
   )

python/tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{35,36,37,38,39,310}-{cpp,python}
+    py{37,38,39,310}-{cpp,python}
 
 [testenv]
 usedevelop=true
@@ -14,7 +14,7 @@ setenv =
 commands =
     python setup.py -q build_py
     python: python setup.py -q build
-    py{35,36,37,38,39,310}-cpp: python setup.py -q build --cpp_implementation --warnings_as_errors --compile_static_extension
+    py{37,38,39,310}-cpp: python setup.py -q build --cpp_implementation --warnings_as_errors --compile_static_extension
     python: python setup.py -q test -q
     cpp: python setup.py -q test -q --cpp_implementation
     python: python setup.py -q test_conformance

tests.sh

@@ -116,12 +116,12 @@ build_dist_install() {
 
   # Try to install Java
   pushd java
-  use_java jdk8
+  use_java jdk11
   $MVN install
   popd
 
   # Try to install Python
-  virtualenv --no-site-packages venv
+  python3 -m venv venv
   source venv/bin/activate
   pushd python
   python3 setup.py clean build sdist
@@ -189,6 +189,10 @@ build_golang() {
 use_java() {
   version=$1
   case "$version" in
+    jdk11)
+      export PATH=/usr/lib/jvm/java-11-openjdk-amd64/bin:$PATH
+      export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
+      ;;
     jdk8)
       export PATH=/usr/lib/jvm/java-8-openjdk-amd64/bin:$PATH
       export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
@@ -268,7 +272,7 @@ build_java_linkage_monitor() {
   # Linkage Monitor checks compatibility with other Google libraries
   # https://github.com/GoogleCloudPlatform/cloud-opensource-java/tree/master/linkage-monitor
 
-  use_java jdk8
+  use_java jdk11
   internal_build_cpp
 
   # Linkage Monitor uses $HOME/.m2 local repository
@@ -330,39 +334,18 @@ build_objectivec_cocoapods_integration() {
 build_python() {
   internal_build_cpp
   cd python
-  if [ $(uname -s) == "Linux" ]; then
-    envlist=py\{35,36\}-python
-  else
-    envlist=py\{36\}-python
-  fi
-  python -m tox -e $envlist
+  tox --skip-missing-interpreters
   cd ..
 }
 
 build_python_version() {
   internal_build_cpp
   cd python
   envlist=$1
-  python -m tox -e $envlist
+  tox -e $envlist
   cd ..
 }
 
-build_python33() {
-  build_python_version py33-python
-}
-
-build_python34() {
-  build_python_version py34-python
-}
-
-build_python35() {
-  build_python_version py35-python
-}
-
-build_python36() {
-  build_python_version py36-python
-}
-
 build_python37() {
   build_python_version py37-python
 }
@@ -384,12 +367,7 @@ build_python_cpp() {
   export LD_LIBRARY_PATH=../src/.libs # for Linux
   export DYLD_LIBRARY_PATH=../src/.libs # for OS X
   cd python
-  if [ $(uname -s) == "Linux" ]; then
-    envlist=py\{35,36\}-cpp
-  else
-    envlist=py\{36\}-cpp
-  fi
-  tox -e $envlist
+  tox --skip-missing-interpreters
   cd ..
 }
 
@@ -403,22 +381,6 @@ build_python_cpp_version() {
   cd ..
 }
 
-build_python33_cpp() {
-  build_python_cpp_version py33-cpp
-}
-
-build_python34_cpp() {
-  build_python_cpp_version py34-cpp
-}
-
-build_python35_cpp() {
-  build_python_cpp_version py35-cpp
-}
-
-build_python36_cpp() {
-  build_python_cpp_version py36-cpp
-}
-
 build_python37_cpp() {
   build_python_cpp_version py37-cpp
 }