Display error message if variable isn't set using playbook

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1

Let’s say I ask for a revision_no from the user. If the user doesn’t input a value, I would like to display a custom message. Right now ansible shows a bunch of “skipping” message, but I know my users would want to know why it skipped.

  • hosts: webservers
    user: deployment

serial: 1

vars_prompt:

  • name: “revision_no”
    prompt: “Input revision number”
    private: no

vars_files:

  • “group_vars/deploy_list”

roles:

  • { role: web, when: revision_no is not defined }
2

That last line is supposed to read “revision_no is defined”

3

There may be a better way to do this but I solved the problem by having a separate task initially that verifies the variable is set and fails the play if not (via the fail module).

  • name: Checking for required variables
    fail: msg=“Playbook execution failed - ‘revision_no’ is required!”
    when: not revision_no

If you don’t want the play to outright fail, you could replace the fail module with something like debug.

4

You can say this specifically:

when: revision_no is not defined

5

This does not work for me. Garrett’s example does …

6

So, here’s the full site.yml file. If I dont input a revision number (I hit enter at the prompt), it throws the error message as expected BUT it also executes the role. I want it to bomb out w/ the error msg and not continue.

7

I believe this is because variables set via vars_prompt are always defined.

A workaround might be to set a default for revision_no and check it doesn’t match in your role, e.g.:

vars_prompt:

  • name: “revision_no"
    prompt: "Input revision number”
    default: “invalid”
    private: no

……

roles:

  • { role: web, when: revision_no != “invalid” }

I’ve not made extensive use of roles so it seems odd to me that a role would still execute when a failure is thrown but it must have something to do with Ansible’s order of execution.

8

I figured it out, not sure if this is valid.

roles:

  • { role: web, when: revision_no }
9

Seems like your variable is defined then, just False.

10

not revision_no works because of you just do Enter it will have empty string and empty string is False. It’s matter of preference but I would test for that.

You can always do debug to see true value:

tasks:

  • debug: msg={{revision_no}}