CI: Build and store a Docker image

.github/workflows/build-docker.yml

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+name: Build and store a Docker image to the GHCR
+on:
+  push:
+  workflow_dispatch:
+
+jobs:
+  build-docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v2
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Cache Docker layers
+        uses: actions/cache@v2
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+      - name: Login to GitHub Container Registry
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push image
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: ./ 
+          file: ./.github/workflows/Dockerfile
+          builder: ${{ steps.buildx.outputs.name }}
+          push: true
+          tags: ghcr.io/precice/openfoam-adapter:latest
+          cache-from: type=local,src=/tmp/.buildx-cache
+          cache-to: type=local,dest=/tmp/.buildx-cache
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}

tools/docker/Dockerfile

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+ARG PRECICE_TAG=latest
+ARG from=precice/precice:${PRECICE_TAG}
+FROM $from
+RUN useradd -ms /bin/bash precice
+ENV DEBIAN_FRONTEND=noninteractive
+
+ARG OPENFOAM_EXECUTABLE=openfoam2306
+# Install OpenFOAM
+# Update the package lists prior to adding the openfoam rep. This is needed because the script installs some packages without updating the package lists. 
+# So sometimes a mirror moved and we get timeouts. 
+RUN apt-get update &&\
+    wget -q -O - https://dl.openfoam.com/add-debian-repo.sh | bash &&\
+    apt-get -qq install ${OPENFOAM_EXECUTABLE}-dev git &&\
+    ln -s $(which ${OPENFOAM_EXECUTABLE} ) /usr/bin/openfoam
+
+ARG OPENFOAM_ADAPTER_REF=develop
+# Build the OpenFOAM adapter
+
+USER precice
+WORKDIR /home/precice
+RUN git clone --depth 1 --branch ${OPENFOAM_ADAPTER_REF} https://github.com/precice/openfoam-adapter.git &&\
+    cd openfoam-adapter && /usr/bin/${OPENFOAM_EXECUTABLE} ./Allwmake