maximize disk space

.github/workflows/build.yml

@@ -22,6 +22,30 @@ jobs:
     timeout-minutes: 360
     name: Build FMO-OS
     steps:
+      - name: Maximize space available on rootfs
+        # Why not use https://github.com/easimon/maximize-build-space directly?
+        # The reason is: we want to maximize the space on rootfs, since that's
+        # where the nix store (`/nix/store`) is located. Github action
+        # https://github.com/easimon/maximize-build-space maximizes
+        # the builder space on ${GITHUB_WORKSPACE}, which is not what we need.
+        # Alternatively, we could move the nix store to ${GITHUB_WORKSPACE}
+        # and use https://github.com/easimon/maximize-build-space as such, but
+        # we suspect other tooling (e.g. cachix) would not work well with such
+        # configuration.
+        run: |
+          echo "Available storage before cleanup:"
+          df -h
+          echo
+          echo "Removing unwanted software... "
+          sudo rm -rf /usr/share/dotnet
+          sudo rm -rf /usr/local/lib/android
+          sudo rm -rf /opt/ghc
+          sudo rm -rf /opt/hostedtoolcache/CodeQL
+          sudo docker image prune --all --force
+          echo "... done"
+          echo
+          echo "Available storage after cleanup:"
+          df -h
       # To use this repository's private action,
       # you must check out the repository
       - name: Checkout