Save Docker image without a dockerfile

My circle.yml looks like this:

version: 2
    working_directory: ~/app
      - image: circleci/node:8.5.0-browsers

  - checkout
  - run: npm install --dev --no-save
  - run: npm run build
  - store_artifacts:
      path: ~/app/dist
  - run: npm run tests

I hope to save a docker image and push it to AWS. I can do that using a dockerfile and creating an image, but I was wondering if I can do it without it. My commands are already running in a docker image, so I am saving the artifacts. Can it just be turned into an image?