Trying it out

Overview

Teaching: 25 min
Exercises: 0 min

Questions

Objectives

• Try our some basic Ansible code

This episode describes the tools we use to build and manage lessons. These simplify many tasks, but make other things more complicated.

Trying it out

Let’s create a folder to get started.

$ mkdir ~/ansible-training && cd ~/ansible-training

1. Module: Ping

$ ansible localhost -m ping

 [WARNING]: Host file not found: /usr/local/etc/ansible/hosts

 [WARNING]: provided hosts list is empty, only localhost is available

localhost | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

2. Module: Setup

$ ansible localhost -m setup 

..... woah!

Trying again: what info are we interest in? e.g. CPU cores:

$ ansible localhost -m setup | grep processor_cores

 [WARNING]: Host file not found: /usr/local/etc/ansible/hosts
 [WARNING]: provided hosts list is empty, only localhost is available
        "ansible_processor_cores": "4",

What’s with all these [WARNING] statements?!

Ansible is looking for an inventory file - let’s create one.

3. Inventory Files

Here’s we’ll create an inventory file for eel and cowfish

$ echo eel.openmicroscopy.org >> inventory-file
$ echo cowfish.openmicroscopy.org >> inventory-file
$ cat inventory-file

eel.openmicroscopy.org
cowfish.openmicroscopy.org

Rather than typing yes for every host, ssh-keyscan takes care of that.

$ cat inventory-file | grep -vP '[\[#]'  | grep -P '\.' | sort | uniq | while read h; do ssh-keyscan $h >> ~/.ssh/known_hosts; done

Trying your first ad-hoc command:

$ ansible all -i inventory-file -a "/bin/echo hello"

A real-world example: nginx versions

$ ansible all -i inventory-file -m shell -a 'rpm -q nginx'

Further reading at ansible.com - getting started

Key Points

• Run simple shell commands

• Add more hosts inventory files

• Gather data from multiple hosts in one command