2.3.1b2 (#1172)

Support for Ubuntu 22.04 and 20.04.

- Update Mininet version
- Install pexpect with pip to support python 3 and 2
- Update code-check workflow
  - refactor to enable testing python 2 on ubuntu 22.04
  - update to actions/checkout@v3 (@v2 is deprecated)

errata:

mountCgroups has not actually been renamed, but has been
changed to use cgroupfs-mount and to return the cgroups version.

.github/workflows/run-tests.yaml

@@ -9,48 +9,38 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        include:
-          - os: ubuntu-22.04
-            python-version: 3.x
-          - os: ubuntu-20.04
-            python-version: 3.x
-          - os: ubuntu-20.04
-            python-version: 2.x
+        os: [ubuntu-22.04, ubuntu-20.04]
+        py: [python3, python2]
     steps:
       - name: Check out Mininet source
-        uses: actions/checkout@v2
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
-        with:
-          python-version: ${{ matrix.python-version }}
+        uses: actions/checkout@v3
+      - name: Install Python ${{ matrix.py }}
+        run: sudo apt install ${{ matrix.py }}
       - name: Install Mininet and base dependencies
         run: |
           sudo apt-get update -qq
           # This seems too slow unfortunately:
           # sudo apt-get upgrade -y -qq
-          PYTHON=`which python` util/install.sh -nv
+          PYTHON=${{ matrix.py }} util/install.sh -nv
       - name: Sanity test
         run: |
           export sudo="sudo env PATH=$PATH"
-          # Verify major python-version number matches python and mininet
-          export PYVER=`echo ${{ matrix.python-version }} | cut -d . -f 1`
-          export CHKVER='px import platform; print(platform.python_version())'
-          python --version |& grep " $PYVER\."
-          echo $CHKVER | $sudo mn -v output | grep " $PYVER\."
+          export PYTHON=${{ matrix.py }}
           # Newer OvS tries OpenFlow15 which crashes ovsc on ubuntu-20.04
           $sudo mn --switch ovs,protocols=OpenFlow13 --test pingall
       - name: Install test dependencies
         run: |
           sudo apt-get install -qq vlan
-          pip install pexpect
+          export PYTHON=${{ matrix.py }}
+          sudo $PYTHON -m pip install pexpect
           util/install.sh -fw
       - name: Run core tests
         run: |
           export sudo="sudo env PATH=$PATH"
-          export PYTHON=`which python`
+          export PYTHON=${{ matrix.py }}
           $sudo $PYTHON mininet/test/runner.py -v
       - name: Run examples tests (quick)
         run: |
           export sudo="sudo env PATH=$PATH"
-          export PYTHON=`which python`
+          export PYTHON=${{ matrix.py }}
           $sudo $PYTHON examples/test/runner.py -v -quick