ansible/jinja: transform dict values

role_tasks_main.yml

---
- name: "define fact user_homes as dict(user name => user home directory)"
  when: user_homes is undefined
  block:
    - name: getent
      getent:
        database: passwd
        split: ":"

    - name: set fact
      set_fact:
        # python would do: `{key: values[4] for key, values in getent_passwd}`
        #
        # instead in jinja:
        #   build a dict by passing all usernames to…
        #   … zip which concatenates them with the result of passing all usernames through…
        #   … map which extracts the homedir as getent_passwd[current username][4]
        user_homes: >
          {{ dict(getent_passwd.keys()
                  | zip(getent_passwd.keys()
                        | map('extract', getent_passwd, 4)
                        )
                  )
          }}