Beginner: Ansible The offending line appears to be

Solution 1:

Pay attention to indentation for parameters:

Looks like the deb: parameter (and the rest of its section) needs greater indentation. Thus instead of,

    - name: Install .deb packages from the internet.
      apt:
      deb:
      - https://packagecloud.io/AtomEditor/atom/any/
      - ...

add some indentation to deb: to make it a parameter,

    - name: Install .deb packages from the internet.
      apt:
        deb:
        - https://packagecloud.io/AtomEditor/atom/any/
        - ...

Without indentation Ansible won't understand deb: to be a parameter of the apt: module; rather it will try to make sense of it as a directive affecting how apt: is used (so like notify:, become:, ignore_errors: etc)

the same for update_cache: so instead of,

    - name: Install a list of packages
      update_cache: yes
      apt:
        pkg:
        - AtomEditor
        - ...

move update_cache: within apt: and indent it,

    - name: Install a list of packages
      apt:
        update_cache: yes
        pkg:
        - AtomEditor
        - ...

similarly,

    - name: Remove useless packages from the cache
      apt:
        autoclean: yes

and finally I don't understand what you're trying to do with the 'no tracking' part; I'm not aware of a vars: module. Maybe you want to remove those packages if present, in which case see the documentation for the apt: module, esp. the 'Remove "foo" package' example.