Add CI rules for GitHub hosted Ubuntu runners.

These rules are heavily inspired by the existing CI scripts.

.github/workflows/build.yaml

@@ -0,0 +1,128 @@
+name: build
+on:
+  workflow_dispatch:
+  push:
+  pull_request:
+
+concurrency: ci-${{ github.ref }}
+
+jobs:
+
+  ubuntu:
+    # For available GitHub-hosted runners, see:
+    # https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners
+    runs-on: ubuntu-latest
+
+    name: ubuntu (${{ matrix.compiler }})
+
+    strategy:
+      # Allow other runners in the matrix to continue if some fail
+      fail-fast: false
+
+      matrix:
+        compiler: [gcc, clang]
+        include:
+          - compiler: gcc
+            compiler-pkgs: "g++ gcc"
+            cc: "gcc"
+            cxx: "g++"
+            ccache-max: 600M
+          - compiler: clang
+            compiler-pkgs: "clang libomp-dev"
+            cc: "clang"
+            cxx: "clang++"
+            ccache-max: 500M
+
+    env:
+      CC: ${{ matrix.cc }}
+      CXX: ${{ matrix.cxx }}
+
+    steps:
+      - name: get CPU information
+        run: lscpu
+
+      - name: checkout repository
+        uses: actions/checkout@v4
+
+      - name: install dependencies
+        env:
+          COMPILER_PKGS: ${{ matrix.compiler-pkgs }}
+        run: |
+          sudo apt -qq update
+          sudo apt install -y ${COMPILER_PKGS} cmake gfortran libopenblas-dev \
+            unzip libopenmpi-dev libmumps-dev libparmetis-dev
+
+      - name: prepare ccache
+        # create key with human readable timestamp
+        # used in action/cache/restore and action/cache/save steps
+        id: ccache-prepare
+        run: |
+          echo "key=ccache:ubuntu:${{ matrix.compiler }}:${{ github.ref }}:$(date +"%Y-%m-%d_%H-%M-%S"):${{ github.sha }}" >> $GITHUB_OUTPUT
+
+      - name: restore ccache
+        # setup the GitHub cache used to maintain the ccache from one job to the next
+        uses: actions/cache/restore@v4
+        with:
+          path: ~/.ccache
+          key: ${{ steps.ccache-prepare.outputs.key }}
+          # Prefer caches from the same branch. Fall back to caches from the dev branch.
+          restore-keys: |
+            ccache:ubuntu:${{ matrix.compiler }}:${{ github.ref }}
+            ccache:ubuntu:${{ matrix.compiler }}:
+
+      - name: configure ccache
+        env:
+          CCACHE_MAX: ${{ matrix.ccache-max }}
+        run: |
+          test -d ~/.ccache || mkdir ~/.ccache
+          echo "max_size = $CCACHE_MAX" >> ~/.ccache/ccache.conf
+          echo "compression = true" >> ~/.ccache/ccache.conf
+          ccache -s
+          echo "/usr/lib/ccache" >> $GITHUB_PATH
+
+      - name: configure
+        run: |
+          mkdir {GITHUB_WORKSPACE}/build
+          cd ${GITHUB_WORKSPACE}/build
+          cmake -DCMAKE_BUILD_TYPE="Release" \
+                -DCMAKE_INSTALL_PREFIX="${GITHUB_WORKSPACE}" \
+                -DCMAKE_C_COMPILER_LAUNCHER="ccache" \
+                -DCMAKE_CXX_COMPILER_LAUNCHER="ccache" \
+                -DCMAKE_Fortran_COMPILER_LAUNCHER="ccache" \
+                -DBLA_VENDOR="OpenBLAS" \
+                -DWITH_OpenMP=ON \
+                -DWITH_LUA=ON \
+                -DWITH_Zoltan=ON \
+                -DWITH_Mumps=ON \
+                -DCREATE_PKGCONFIG_FILE=ON \
+                -DWITH_MPI=ON \
+                -DMPI_TEST_MAXPROC=2 \
+                -DMPIEXEC_PREFLAGS="--allow-run-as-root" \
+                ..
+
+      - name: build
+        run: |
+           cd ${GITHUB_WORKSPACE}/build
+           cmake --build .
+
+      - name: check
+        timeout-minutes: 20
+        run: |
+           cd ${GITHUB_WORKSPACE}/build
+           ctest .
+
+      - name: ccache status
+        continue-on-error: true
+        run: ccache -s
+
+      - name: save ccache
+        # Save the cache after we are done (successfully) building
+        # This helps to retain the ccache even if the subsequent steps are failing.
+        uses: actions/cache/save@v4
+        with:
+          path: ~/.ccache
+          key: ${{ steps.ccache-prepare.outputs.key }}
+
+      - name: install
+        run: |
+          cmake --install .