passing secrets from gh action to docker builder

Dockerfile

...
COPY package*.json ./
RUN --mount=type=secret,id=npmrc,target=/usr/local/app/.npmrc \
    npm ci
...

workflow.yml

...

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v2

      - name: Create authenticated .npmrc for Docker build runner
        run: |
          echo "//npm.pkg.github.com/:_authToken=${{ github.token }}" > $HOME/.npmrc
          cat .npmrc >> $HOME/.npmrc
          echo "npmrc_path=$HOME/.npmrc" >> "$GITHUB_ENV"

      - name: Build and push
        uses: docker/build-push-action@v4
        with:
          push: false
          tags: vorant94-io/web:latest
          secret-files: |
            npmrc=${{ env.npmrc_path }}