Hi
On Mon, 27 Apr 2020 at 23:15, Michael S. Moody
<michael.mo...@michaelsmoody.com> wrote:
>
> Good afternoon,
>
> I opened an issue on GitHub, and was directed here, which is the obvious
> place. (I initially thought that the behavior was indeed a bug, but there was
> some clarity added).
>
> What would be the preferred method to perform input validation on a user
> supplied variable provided via extra vars? Is the recommended approach to
> simply handle an error (and end the host, play or task) if the variable
> doesn't match an expected input, as it is not possible to overwrite it due to
> precedence?
>
> As it was, we were trying to use "-e" for the extra variables, and then using
> set_fact to overwrite it if it didn't meet the expected requirements.
>
> This is what I was trying:
>
> ###This works as expected
> - name: "Setting Deploy Environment Variable for Deployment Tasks"
> set_fact:
> deploy_environment: "Development"
>
> when: deploy_environment is undefined
>
> tags:
> - variable-test-task
>
> ###This does not work
> - name: "Setting Deploy Environment Variable for Deployment Tasks"
> set_fact:
> deploy_environment: "Development"
>
> when: deploy_environment != "Development"
>
> tags:
> - variable-test-task
>
> ###This does not work
> - name: "Setting Deploy Environment Variable for Deployment Tasks"
> set_fact:
> deploy_environment: "Development"
>
> when: deploy_environment == "Production"
>
> tags:
> - variable-test-task
>
> ###This does not work, playing with syntax, might be expected
> - name: "Setting Deploy Environment Variable for Deployment Tasks"
> set_fact:
> deploy_environment: "Development"
>
> when: not (deploy_environment is defined) or not ((deploy_environment ==
> 'Development') or (deploy_environment == 'Production'))
>
> tags:
> - variable-test-task
>
> ###This does not work, playing with syntax, might be expected
> - name: "Setting Deploy Environment Variable for Deployment Tasks"
> set_fact:
> deploy_environment: "Development"
>
> when: (deploy_environment is undefined) or ((deploy_environment !=
> 'Development') or (deploy_environment != 'Production'))
>
> tags:
> - variable-test-task
>
> ###This does not work, playing with syntax, might be expected
> - name: "Setting Deploy Environment Variable for Deployment Tasks"
> set_fact:
> deploy_environment: "Development"
>
> when: (deploy_environment != 'Development') or (deploy_environment !=
> 'Production')
>
> tags:
> - variable-test-task
>
>
> And that was patiently explained to have been by design. I'm open to
> suggestions on the best overall way to accomplish this.
You're right about the precedence getting in the way of altering
variables set with '-e', that's indeed not possible.
However this is usually not a problem, as long as you use it to
override something that is set already.
But set_fact can't win from '-e', so that won't work.
There are a few alternatives.
I usually avoid having to change variables directly, and instead use
two variables. One meant for 'internal' use inside the role, which as
a convention, I prefix with an underscore.
For instance '_env'. And then have an 'external' var meant for command
line usage, say 'deploy_environment'. Then any logic with set_fact etc
will work.
But, looking at your code again - all you seem to want is to provide a
default for the 'deploy_environment' variable.
In that case, '-e' will just work fine, for instance:
- hosts: localhost
connection: local
gather_facts: no
vars:
deploy_environment: Development
tasks:
- debug:
msg: |
We are deploying the {{ deploy_environment }} environment now
If you run this without any '-e' switched, it will use Development.
And you can just override it with '-e deploy_environment=Production'.
For failing gracefully, look at the 'assert' module. The following
example ensure only valid environments are being used:
---
- hosts: localhost
connection: local
gather_facts: no
vars:
deploy_environments:
- Development
- Production
- Testing
- Acceptance
deploy_environment: "{{ deploy_environments | first }}"
tasks:
- name: Ensure we use a valid environment
assert:
that:
- deploy_environment in deploy_environments
fail_msg: "Available environments are: {{ deploy_environments
| join(', ') }}."
- debug:
msg: |
We are deploying the {{ deploy_environment }} environment now
Dick
--
Dick Visser
Trust & Identity Service Operations Manager
GÉANT
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