Use actions/setup-python action to install Python for action

At the time the arduino/compile-sketches action was converted to a composite action, the only step type supported for
this action type was "run", where shell commands are executed. For this reason, it was necessary to use shell commands
to install Python.

Since that time, support was added for using other actions in composite action steps. This allows Python to be set up
for use by the action in a more simple and efficient manner via the `actions/setup-python` action.

The Python-based infrastructure workflows are also migrated to using `actions/setup-python` action for installing
Python. In order to ensure the same version of Python is used for CI as the action, the version of Python used by the
project is defined in a `.python-version` file, and all `actions/setup-python` steps pointed to that file.

In order to ensure the stability of the action, the `actions/setup-python` action is pinned to a patch version. Although
the common practice is to only pin the major version of actions in CI workflows, in this case there is no benefit to
doing so for the `actions/setup-python` action since patch level bumps are going to be received from Dependabot
regardless.

Author: per1234

.github/workflows/lint-python.yml

@@ -5,11 +5,13 @@ on:
     paths:
       - '.github/workflows/lint-python.yml'
       - 'compilesketches/**.py'
+      - '.python-version'
 
   push:
     paths:
       - '.github/workflows/lint-python.yml'
       - 'compilesketches/**.py'
+      - '.python-version'
 
   # Scheduled trigger checks for workflow failures resulting from updates to the linting tools
   schedule:
@@ -32,6 +34,11 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
 
+      - name: Install Python
+        uses: actions/setup-python@v4.5.0
+        with:
+          python-version-file: .python-version
+
       - name: Run the set up script
         id: setup
         run: |
@@ -40,7 +47,7 @@ jobs:
       - name: Install flake8
         run: |
           source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
-          "${{ steps.setup.outputs.python-command }}" \
+          python \
             -m \
               pip install \
                 flake8 \

.github/workflows/test-python.yml

@@ -4,12 +4,14 @@ on:
   pull_request:
     paths:
       - '.github/workflows/test-python.yml'
+      - '.python-version'
       - 'action-setup.sh'
       - 'compilesketches/**'
 
   push:
     paths:
       - '.github/workflows/test-python.yml'
+      - '.python-version'
       - 'action-setup.sh'
       - 'compilesketches/**'
 
@@ -39,6 +41,11 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
 
+      - name: Install Python
+        uses: actions/setup-python@v4.5.0
+        with:
+          python-version-file: .python-version
+
       - name: Run the set up script
         id: setup
         run: |
@@ -47,7 +54,7 @@ jobs:
       - name: Install test dependencies
         run: |
           source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
-          "${{ steps.setup.outputs.python-command }}" \
+          python \
             -m \
               pip install \
                 --requirement "${{ env.PYTHON_PROJECT_TESTS_PATH }}/requirements.txt"
@@ -56,7 +63,7 @@ jobs:
         run: |
           source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
           export PYTHONPATH="${{ env.PYTHON_PROJECT_PATH }}"
-          "${{ steps.setup.outputs.python-command }}" \
+          python \
             -m \
               coverage run \
                 --rcfile="${{ env.PYTHON_PROJECT_TESTS_PATH }}/.coveragerc" \
@@ -65,15 +72,15 @@ jobs:
                   pytest "${{ env.PYTHON_PROJECT_TESTS_PATH }}"
           # Generate coverage data file for consumption by `codecov/codecov-action`.
           # Otherwise that action generates the file using the system Python environment, which doesn't work.
-          "${{ steps.setup.outputs.python-command }}" \
+          python \
             -m \
               coverage xml \
                 -o "${{ github.workspace }}/${{ env.COVERAGE_DATA_FILENAME }}"
 
       - name: Display code coverage report
         run: |
           source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
-          "${{ steps.setup.outputs.python-command }}" \
+          python \
             -m \
               coverage report
 

.python-version

@@ -0,0 +1 @@
+3.8

action-setup.sh

@@ -2,8 +2,6 @@
 
 # Set up the Python environment for the action's script to run in
 
-readonly PYTHON_PACKAGE_VERSION='3.8'
-
 # https://stackoverflow.com/a/29835459
 SCRIPT_PATH="$(
   CDPATH='' \
@@ -15,32 +13,20 @@ SCRIPT_PATH="$(
 )"
 readonly SCRIPT_PATH
 
-readonly PYTHON_COMMAND="python${PYTHON_PACKAGE_VERSION}"
 readonly PYTHON_VENV_PATH="${SCRIPT_PATH}/compilesketches/.venv"
 readonly PYTHON_VENV_ACTIVATE_SCRIPT_PATH="${PYTHON_VENV_PATH}/bin/activate"
 
-# Install Python
-sudo apt-get install --yes software-properties-common > /dev/null
-sudo add-apt-repository --yes ppa:deadsnakes/ppa > /dev/null
-sudo apt-get update --yes > /dev/null
-sudo apt-get install --yes python${PYTHON_PACKAGE_VERSION} > /dev/null
-echo "Using Python version: $("$PYTHON_COMMAND" --version)"
-
-sudo apt-get install --yes python3-setuptools > /dev/null
-sudo apt-get install --yes python${PYTHON_PACKAGE_VERSION}-venv > /dev/null
-
 # Create Python virtual environment
-"$PYTHON_COMMAND" -m venv --system-site-packages "$PYTHON_VENV_PATH"
+python -m venv --system-site-packages "$PYTHON_VENV_PATH"
 
 # Activate Python virtual environment
 # shellcheck source=/dev/null
 . "$PYTHON_VENV_ACTIVATE_SCRIPT_PATH"
 
 # Install Python dependencies
-"$PYTHON_COMMAND" -m pip install --upgrade pip > /dev/null
-"$PYTHON_COMMAND" -m pip install --quiet --requirement "${SCRIPT_PATH}/compilesketches/requirements.txt"
+python -m pip install --upgrade pip > /dev/null
+python -m pip install --quiet --requirement "${SCRIPT_PATH}/compilesketches/requirements.txt"
 
 # Set outputs for use in GitHub Actions workflow steps
 # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions#setting-an-output-parameter
-echo "::set-output name=python-command::$PYTHON_COMMAND"
 echo "::set-output name=python-venv-activate-script-path::$PYTHON_VENV_ACTIVATE_SCRIPT_PATH"

action.yml

@@ -49,6 +49,11 @@ inputs:
 runs:
   using: composite
   steps:
+    - name: Install Python
+      uses: actions/setup-python@v4.5.0
+      with:
+        python-version-file: ${{ github.action_path }}/.python-version
+
     - name: Run the set up script
       id: setup
       shell: bash
@@ -74,4 +79,4 @@ runs:
         INPUT_SKETCHES-REPORT-PATH: ${{ inputs.sketches-report-path }}
       run: |
         source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
-        "${{ steps.setup.outputs.python-command }}" "${{ github.action_path }}/compilesketches/compilesketches.py"
+        python "${{ github.action_path }}/compilesketches/compilesketches.py"