overriding variables via command line

[dmfigol]

Hi,
I've done research, read through multiple issues touching default vars/overrides/env vars (I think the closest to my problem is this comment #181 (comment)) but I am still confused about best practices.

My requirements:

1. I want to use vars/go templating instead of relying on env vars, so that I can see the command fully on execution, I'd refer to env vars for something that is relevant to my application/script and not task itself (e.g. secrets)
2. I want to define vars explicitly, so that users can quickly see what they can/should provide
3. I want to provide them via command line
4. Ideally I want to make some variables mandatory

Here is an example of Taskfile:

version: '3'
tasks:
  test:
    cmds:
      - echo "{{.ID}}"
    vars:
      ID: '123'

ID=456 task test doesn't produce result I expect (overriden variable), unless I do:

    vars:
      ID: "{{.ID | default 123}}"

but it is cumbersome. At least it works.
For 4 I am using preconditions like this:

      - sh: "[ '{{.FILE}}' != '' ]"
        msg: "Variable FILE is not set"

but it also feels a little weird.

Any recommendations/best practices?