1.2-thebasics

Workshop Exercise - The Ansible Basics

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Table of Contents

• Objective
• Guide
  • Step 1 - Work with your Inventory
  • Step 2 - Listing Modules and Getting Help

Objective

In this exercise, we are going to explore the latest Ansible command line utility ansible-navigator to learn how to work with inventory files and the listing of modules when needing assistance. The goal is to familarize yourself with how ansible-navigator works and how it can be used to enrich your Ansible experience.

This exercise will cover

• Working with inventory files
• Locating and understanding an ini formatted inventory file
• Listing modules and getting help when trying to use them

Guide

Step 1 - Work with your Inventory

An inventory file is a text file that specifies the nodes that will be managed by the control machine. The nodes to be managed may include a list of hostnames or IP addresses of those nodes. The inventory file allows for nodes to be organized into groups by declaring a host group name within square brackets ([]).

To use the ansible-navigator command for host management, you need to provide an inventory file which defines a list of hosts to be managed from the control node. In this lab, the inventory is provided by your instructor. The inventory file is an ini formatted file listing your hosts, sorted in groups, additionally providing some variables. It looks like:

[web]
node1 ansible_host=<X.X.X.X>
node2 ansible_host=<Y.Y.Y.Y>
node3 ansible_host=<Z.Z.Z.Z>

[control]
ansible-1 ansible_host=44.55.66.77

Ansible is already configured to use the inventory specific to your environment. We will show you in the next step how that is done. For now, we will execute some simple commands to work with the inventory.

To reference all the inventory hosts, you supply a pattern to the ansible-navigator command. ansible-navigator inventory has a --list option which can be useful for displaying all the hosts that are part of an inventory file including what groups they are associated with.

[student@ansible-1 rhel_workshop]$ cd /home/student
[student@ansible-1 ~]$ ansible-navigator inventory --list -m stdout
{
    "_meta": {
        "hostvars": {
            "ansible-1": {
                "ansible_host": "3.236.186.92"            },
            "node1": {
                "ansible_host": "3.239.234.187"
            },
            "node2": {
                "ansible_host": "75.101.228.151"
            },
            "node3": {
                "ansible_host": "100.27.38.142"
            }
        }
    },
    "all": {
        "children": [
            "control",
            "ungrouped",
            "web"
        ]
    },
    "control": {
        "hosts": [
            "ansible-1"
        ]
    },
    "web": {
        "hosts": [
            "node1",
            "node2",
            "node3"
        ]
    }
}

NOTE: -m is short for --mode which allows for the mode to be switched to standard output instead of using the text-based user interface (TUI).

If the --list is too verbose, the option of --graph can be used to provide a more condensed version of --list.

[student@ansible-1 ~]$ ansible-navigator inventory --graph -m stdout
@all:
  |--@control:
  |  |--ansible-1
  |--@ungrouped:
  |--@web:
  |  |--node1
  |  |--node2
  |  |--node3

We can clearly see that nodes: node1, node2, node3 are part of the web group, while ansible-1 is part of the control group.

An inventory file can contain a lot more information, it can organize your hosts in groups or define variables. In our example, the current inventory has the groups web and control. Run Ansible with these host patterns and observe the output:

Using the ansible-navigator inventory command, we can also run commands that provide information only for one host or group. For example, give the following commands a try to see their output.

[student@ansible-1 ~]$ ansible-navigator inventory --graph web -m stdout
[student@ansible-1 ~]$ ansible-navigator inventory --graph control -m stdout
[student@ansible-1 ~]$ ansible-navigator inventory --host node1 -m stdout

Tip

The inventory can contain more data. E.g. if you have hosts that run on non-standard SSH ports you can put the port number after the hostname with a colon. Or you could define names specific to Ansible and have them point to the "real" IP or hostname.

Step 2 - Listing Modules and Getting Help

Ansible Automation Platform comes with multiple supported Execution Environments (EEs). These EEs come with bundled supported collections that contain supported content, including modules.

Tip

In ansible-navigator exit by pressing the button ESC.

To browse your available modules first enter interactive mode:

$ ansible-navigator

First browse a collection by typing :collections

:collections

To browse the content for a specific collections, type the corresponding number. For example in the example screenshot above the number 0 corresponds to amazon.aws collection. To zoom into collection type the number 0.

0

Get help for a specific module including usage by zooming in further. For example the module ec2_tag corresponds to 24.

:24

Scrolling down using the arrow keys or page-up and page-down can show us documentation and examples.

You can also skip directly to a particular module by simply typing :doc namespace.collection.module-name. For example typing :doc amazon.aws.ec2_tag would skip directly to the final page shown above.

Tip

Different execution environments can have access to different collections, and different versions of those collections. By using the built-in documentation you know that it will be accurate for that particular version of the collection.

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