Pre-Conditions for a role to execute tasks

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1

Hi,

Suppose I have a role called Ruby. I will

  1. install build tools
  2. download ruby source
  3. compile
  4. install

Because it takes long time to do all these tings and I don’t want to it it the expected Ruby already installed.

How could I do it?

I could do it using the “when” condition on every step. like the following:

  • name: check if ruby installed
    shell: ls /opt/rubies
    register: ruby_installed

  • name: install dependencies
    apt: name =…
    when: ruby_installed.stdout.find(ruby_full_version) == -1

Wonder if there is any better solution? like a precondition for all the tasks in a role?

Also I found it would be convenient if we have module like Java, Ruby to install various version of the packages. Like Chef they have Java cookbook.

Any suggestion is really appreciated.

Cheers,
Rui

2

If you ever want to skip a large number of tasks, usage of “group_by” can easily do this.

  • hosts: all
    tasks:

  • stat: path=/path/to/ruby
    register: ruby

  • group_by: key=ruby-{{ ruby.stat.exists }}

  • hosts: ruby-False
    tasks:

  • …

or roles, etc

This is untested but that’s the general pattern.

Also notice stat is a bit cleaner than “shell” above.