Feature: setup macports (#55)

Author: liss-h

.github/actions/setup_macports/action.yml

@@ -0,0 +1,33 @@
+name: "setup macports"
+description: "setup MacPorts on macOS"
+runs:
+  using: "composite"
+  steps:
+    - name: Cache MacPorts
+      uses: actions/cache@v3
+      id: cache-macports
+      with:
+        path: /opt/local/
+        key: macports-v2.10.7-${{ runner.os }}-${{ inputs.compiler }}
+
+    - name: Fix MacPorts permissions
+      if: ${{ steps.cache-macports.outputs.cache-hit == 'true' }}
+      shell: bash
+      run: sudo chown -R root:wheel /opt/local
+
+    - name: Install MacPorts
+      if: ${{ steps.cache-macports.outputs.cache-hit != 'true' }}
+      shell: bash
+      run: |
+        curl -LO https://github.com/macports/macports-base/releases/download/v2.10.7/MacPorts-2.10.7-15-Sequoia.pkg
+        sudo installer -pkg MacPorts-2.10.7-15-Sequoia.pkg -target /
+
+    - name: Add MacPorts to system paths
+      shell: bash
+      run: |
+        # so sudo can find port
+        echo "/opt/local/bin" | sudo tee -a /etc/paths
+        echo "/opt/local/sbin" | sudo tee -a /etc/paths
+        # also ensure it’s in the user path
+        echo "/opt/local/bin" >> $GITHUB_PATH
+        hash -r