Workshop Exercise - The Ansible Basics

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Table of Contents

• Objective
• Guide
  • Inventory File Basics
  • Module Discovery
  • Accessing Module Documentation

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.

Guide

Inventory File Basics

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 ([]).

Exploring the Inventory

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. An example may look as follows:

[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

To view your inventory with ansible-navigator, use the command ansible-navigator inventory --list -m stdout. This command displays all nodes and their respective groups.

[student@ansible-1 rhel_workshop]$ cd /home/student
[student@ansible-1 ~]$ ansible-navigator inventory --list -m stdout
{
    "_meta": {
        "hostvars": {
            "ansible-1": {
                "ansible_become": "true",
                "ansible_host": "ansible-1.example.com",
                "ansible_ssh_common_args": "-o StrictHostKeyChecking=no",
                "ansible_ssh_private_key_file": "~/.ssh/8qnxkkey.pem",
                "ansible_user": "ec2-user",
                "timeout": 60
            },
            "node1": {
                "ansible_become": "true",
                "ansible_host": "node1.example.com",
                "ansible_ssh_common_args": "-o StrictHostKeyChecking=no",
                "ansible_ssh_private_key_file": "~/.ssh/8qnxkkey.pem",
                "ansible_user": "ec2-user",
                "timeout": 60
            },
            "node2": {
                "ansible_become": "true",
                "ansible_host": "node2.example.com",
                "ansible_ssh_common_args": "-o StrictHostKeyChecking=no",
                "ansible_ssh_private_key_file": "~/.ssh/8qnxkkey.pem",
                "ansible_user": "ec2-user",
                "timeout": 60
            },
            "node3": {
                "ansible_become": "true",
                "ansible_host": "node3.example.com",
                "ansible_ssh_common_args": "-o StrictHostKeyChecking=no",
                "ansible_ssh_private_key_file": "~/.ssh/8qnxkkey.pem",
                "ansible_user": "ec2-user",
                "timeout": 60
            }
        }
    },
    "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).

For a less detailed view, ansible-navigator inventory --graph -m stdout offers a visual representation of groupings.

[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 organize your hosts in groups or define variables. In our example, the current inventory has the groups web and control. Run ansible-navigator with these host patterns and observe the output:

Using the ansible-navigator inventory command, you can run commands that provide information only for one host or group. For example, run the following commands and observe their different outputs.

[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. One can also define names specific to Ansible and have them point to the IP or hostname.

Module Discovery

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

Browse a collection by typing :collections

:collections

Accessing Module Documentation

To explore a specific collection’s modules, enter the number next to the collection name.

For example in the screenshot above, the number 0 corresponds to amazon.aws collection. To zoom into the collection type the number 0.

0

Directly access detailed documentation for any module by specifying its corresponding number. 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 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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