Cannot update JSON file in Docker using Github Action

Question

I try to update a JSON file with Github build information and add it to my docker container. A sample buildinfo.json is part of the C# project. When the build is done, the JSON file in the container remains the sample one and I cannot see what goes wrong here.

Thanks for your help!

My action looks like this:

env:
# Project to publish
BASE_FOLDER: src/WebService
PROJECT_NAME: removed
PROJECT_DOCKERFILE: Dockerfile
PROJECT_CONTAINERNAME: api/removed
DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
DOTNET_CLI_TELEMETRY_OPTOUT: true
# Version settings
NETCORE_VERSION: '6.0.x'
# Docker settings
DOCKER_REGISTRY: removed
DOCKER_NAMESPACE: removed
DOCKER_BUILDKIT: 1

jobs:
  build:
    runs-on: 'ubuntu-latest'

    steps:
    - name: Checkout
      uses: actions/checkout@v2
      with:
        token: ${{ secrets.REPOSITORY_PAT }}
        lfs: 'true'
        submodules: 'recursive'
        fetch-depth: 0

    - name: Setup .NET Core ${{ env.NETCORE_VERSION }}
      uses: actions/setup-dotnet@v1
      with:
        dotnet-version: ${{ env.NETCORE_VERSION }}
        include-prerelease: false
      env:
        NUGET_AUTH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

    - name: Emit build details as JSON
      run: |        
        echo -e -n "{\"buildNumber\":\"${{ github.run_id }}.${{ github.run_number }}.${{ github.run_attempt }}\",\"buildId\":\"${{ github.run_id }}\",\"branchName\":\"${{ github.ref_name }}\",\"commitHash\":\"${{ github.sha }}\"}" > "${{ env.BASE_FOLDER }}/${{ env.PROJECT_NAME }}/buildinfo.json"

    - name: Set up Docker Buildx
      uses: docker/setup-buildx-action@v1

    - name: Log in to registry
      uses: docker/login-action@v1
      with:
        registry: removed
        username: ${{ secrets.AZURE_ACR_USERNAME }}
        password: ${{ secrets.AZURE_ACR_PASSWORD }}

    - name: Build and push container image to registry
      uses: docker/build-push-action@v2
      with:
        push: true
        tags: ${{ env.DOCKER_REGISTRY }}.azurecr.io/${{ env.DOCKER_NAMESPACE }}/${{ env.PROJECT_CONTAINERNAME }}:${{ github.sha }}
        file: ${{ env.BASE_FOLDER }}/${{ env.PROJECT_NAME }}/${{ env.PROJECT_DOCKERFILE }}

With this dockerfile:

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build
WORKDIR /src
COPY ["nuget.config", "."]
COPY ["src/WebService/PROJECTNAME/PROJECTNAME.csproj", "src/WebService/PROJECTNAME/"]
RUN dotnet restore "src/WebService/PROJECTNAME/PROJECTNAME.csproj"
COPY . .
WORKDIR "/src/src/WebService/PROJECTNAME"
RUN dotnet build "PROJECTNAME.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "PROJECTNAME.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "PROJECTNAME.dll"]