ansible-docker: Failed to import the required Python library

Given this vagrantfile:

Vagrant.configure("2") do |config|
  config.vm.box = "generic/ubuntu1804"
  config.vm.define "vagrant"

  config.vm.provision "deploy", type: 'ansible' do |ansible|
    ansible.compatibility_mode = "2.0"
    ansible.playbook = "ansible/deploy.yml"
    ansible.groups = {
      "staging" => ["vagrant"]
    }
  end
end

and this playbook:

- name: Deploy
  hosts: vagrant
  tasks:
    - name: Update and upgrade apt packages
      become: yes
      apt:
        upgrade: 'yes'
        update_cache: yes
        cache_valid_time: 3600
        # Reference: https://github.com/ansible/ansible/issues/56832
        force_apt_get: yes 

    - name: Install Docker & Docker compose
      include_role:
        name: "nickjj.docker"
        apply:
          become: yes
          tags: 
            - docker

    - name: Pip install docker for Ansible's docker_* modules
      pip:
        name: 
          - docker
          - "docker-compose"

    - name: Save services
      local_action:
        module: docker_image
        archive_path: /tmp/{{ item }}.tar
        build:
          path: ../{{ item }}
          pull: yes
        name: {{ item }}
        tag: latest
        force_source: yes
        source: build
      with_items:
        - database
        - server
        - client
        - documents

    - name: Upload services
      copy:
        src: /tmp/{{ item }}.tar
        dest: "{{ base_path }}/{{ item }}.tar"
      with_items:
        - database
        - server
        - client
        - documents

    - name: Load services
      become: yes
      docker_image:
        load_path: "{{ base_path }}/{{ item }}.tar"
        name: {{ item }}
        tag: latest
        source: load
      with_items:
        - database
        - server
        - client
        - documents
      vars:
        ansible_python_interpreter: "/usr/bin/env python-docker"

I get:

failed: [vagrant] (item=database) => {"ansible_loop_var": "item", "changed": false, "item": "database", "msg": "Failed to import the required Python library (Docker SDK for Python: docker (Python >= 2.7) or docker-py (Python 2.6)) on ubuntu1804.localdomain's Python /usr/local/bin/python-docker. Please read module documentation and install in the appropriate location. If the required library is installed, but Ansible is using the wrong Python interpreter, please consult the documentation on ansible_python_interpreter, for example via `pip install docker` or `pip install docker-py` (Python 2.6). The error was: No module named 'docker'"}