Split string to get all but the last element

• Ansible's regex_replace() filter:

mystr | regex_replace('\\.[^.]+$', '')

• Using map filter, trim filter, and Python list slicing:

1. Apply the trim filter to every element of your list using the map filter
2. Using python list slicing to get everything but the last
3. Join the elements back

$ ansible localhost -m debug \
-a "msg={{ (mystr.split('.') | map('trim'))[:-1] | join('.') }}" \
-e "mystr=I.to.be.war"
localhost | SUCCESS => {
    "msg": "I.to.be"
}

• Using a regex to match the first part of the string:

$ ansible localhost -m debug \
-a 'msg={{ mystr | regex_replace("^(.*)\\.[^.]*$", "\\1") }}' \
-e "mystr=I.to.be.war"
localhost | SUCCESS => {
    "msg": "I.to.be"
}

• Using the splitext filter:

- debug:
    var: "'I.To.Be.war' | splitext | first | trim"

ok: [localhost] => 
  '''I.To.Be.war'' | splitext | first | trim': I.To.Be

• Using regex_replace() filter to create a directory:

- name: "Create folder"
  ansible.builtin.file:
    path: '{{ sample_variable_name_from_group_vars_all | regex_replace("^(.*)\\.[^.]*$", "\\1") }}'
    state: directory