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Asked: 2024-09-25T16:33:51+05:30 In:

How can I use Ansible facts to determine if the operating system is an EL (Enterprise Linux) variant based on its distribution or OS family?

I’ve been diving into Ansible lately, and I hit a bit of a snag that I could really use some help with. So, you know how Ansible collects all those facts about the systems it’s interacting with? I’ve got this project where I need to identify whether the target systems are some flavor of Enterprise Linux (like CentOS, RHEL, or Fedora). The tricky part is that I want to filter these based on the distribution or OS family.

Here’s where I’m getting stuck. I know that facts can give us a ton of information, but I’m unsure how to sift through them to specifically check for EL variants. I’m guessing there must be a way to use the info Ansible gathers to figure this out, but I haven’t been able to piece it all together. Do I need to look at `ansible_distribution` and `ansible_distribution_major_version`, or is there another fact that might be more useful?

Also, if I identify that a system is indeed an EL variant, what’s the best way to go about performing different tasks based on that? For example, maybe I want to install specific packages or configure certain services only on those systems. Is there a preferred method to handle conditional statements for tasks based on the OS family?

I’ve seen some folks using variables and conditionals in their playbooks, which looks clean, but I’m still figuring out where facts come into play. I’d love some insights or example snippets if anyone’s willing to share. Are there any best practices for checking these facts and branching logic in Ansible?

Thanks in advance for your help! I’m sure I’m not the only one out there trying to get a better grip on this, so any advice or experience you all have would be super useful!

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    2 Answers



    1. Ansible Help

      Help with Identifying Enterprise Linux Systems in Ansible

      Looks like you’re diving into some pretty cool stuff with Ansible! To check if your target systems are some flavor of Enterprise Linux, you can definitely rely on the facts that Ansible gathers. The two main facts you want to look at are:

      • ansible_distribution: This tells you the name of the distribution (like CentOS, RHEL, Fedora).
      • ansible_distribution_major_version: This gives you the major version of the distribution.

      To check if a system is an EL variant, you can use these facts in your playbook. Here’s a simple snippet that demonstrates how to filter and perform tasks based on the distribution:

      
- hosts: all
  tasks:
    - name: Check if the system is an EL variant
      debug:
        msg: "This is an EL variant!"
      when: ansible_distribution in ['CentOS', 'RedHat', 'Fedora']

    - name: Install a package specific to EL
      yum:
        name: httpd
        state: present
      when: ansible_distribution in ['CentOS', 'RedHat', 'Fedora']

      This example prints a message and installs the httpd package only on systems that are CentOS, RHEL, or Fedora. The when conditional is what makes it specific to those distributions.

      For best practices, keep your conditions simple and readable. You could also use a variable for the EL distributions if you want to keep it clean, like this:

      
vars:
  el_variants: ['CentOS', 'RedHat', 'Fedora']

tasks:
  - debug:
      msg: "This is an EL variant!"
    when: ansible_distribution in el_variants
  - yum:
      name: httpd
      state: present
    when: ansible_distribution in el_variants

      This way, if you ever need to add or change the list of EL variants, you can just update the el_variants variable in one place!

      Hope this helps you get a clearer picture of using facts and conditionals in your Ansible playbooks. Happy automating!



    2. To determine whether your target systems are any flavor of Enterprise Linux (like CentOS, RHEL, or Fedora) using Ansible facts, you will want to look at the `ansible_distribution` and `ansible_distribution_major_version` facts. These facts provide specific information about the OS running on your target machines. For instance, you can easily check if `ansible_distribution` is either “CentOS,” “RedHat,” or “Fedora.” Additionally, if you wish to be more specific in your checks, you can combine facts like this:

      - name: Check if Linux is EL variant
    debug:
      msg: "System is a supported Enterprise Linux variant"
    when: ansible_distribution in ['CentOS', 'RedHat', 'Fedora']

      Once you’ve identified that a system is an EL variant, you can utilize conditional statements to execute specific tasks based on that criteria. To perform different tasks for Enterprise Linux systems, you can leverage the `when` conditional in your tasks. You might structure your tasks as follows:

      - name: Install a package on EL variants
    yum:
      name: your_package
      state: present
    when: ansible_distribution in ['CentOS', 'RedHat', 'Fedora']

      This approach keeps your playbook clean and modular while ensuring that tasks are only executed on the specified distributions. Additionally, ensure to validate the output of `ansible_facts` to avoid mismatch in names for other variations you might encounter. Using conditionals effectively allows for tailored configurations depending on the environment.


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