[LINUX] Introduction to Ansible Part 1'Hello World !!'

What is Ansible?

Overview

Called a configuration management tool The remote machine and server can be set automatically according to the program. Even if you do not repeat the same work and set up the server A convenient friend who will set up any number of units as long as you give Ansible the code. The test environment can be reproduced!

merit

1. ** Idempotent **
   The same result is guaranteed no matter how many times you do it from the same program.
2. ** Easy to understand **
   The main program is built on YAML and is really easy to understand and read.
3. ** Agentless **
   Speaking of configuration management tools, there are various other services, but
   Many will not work without installing the software on remote hosts.
   However, Ansible does not have to do that, just an SSH connection and it works on its own!
4. ** Any shell command can be executed on the remote server **
   You can easily implement shell commands in your program. Thank you.
   By the way, there are many modules available, which are convenient.
5. ** Ready to use **
   There is little prior knowledge required to be able to use it.
   Why not write a command in the playbook?
   And the remote host is specified like this. I feel like I can start with.

Regarding Ansible installation

** Mac users ** are really comfortable. Search for ʻAnsible installation. ** Windows users ** are a little hard. I also struggled. I'm only struggling anymore. If you have a virtual environment, it may not be a problem, but I started by launching it on a docker container. By the way, recently I am using the one launched on ec2. If you search for docker Ansible or ʻaws Ansible, you will find various results. [By the way, the article I referred to] Docker edition [Ansible] Ansible hands-on with Docker AWS edition [Introduction to Ansible] Let's run Ansible in EC2 environment

Try to output "Hello World"

This time, I will make something that outputs Hello World using localHost (self). I think you can understand the basics of Ansible with this.

Required files

file organization

helloworld
├── playbook.yml
└── inventory

playbook.yml Setting management script in Ansible. Basically, I spend my time writing this while using Ansible. Simply put, write the instructions you want the server to do. inventory A file that describes which remote host is targeted. INI format.

Contents of inventory

inventory

[target]
localhost

Contents of playbook

playbook.yml

---
- hosts: all
  tasks:
    - name: Hello World!
      debug:
        msg: "Hello World!"

Please note that indentation is important for YAML format files.

Try to run

localhost

$ ansible-playbook -i inventory playbook.yml
PLAY [all] **********************************************************

TASK [Gathering Facts] **********************************************
ok: [localhost]

TASK [helloworld : Hello World!] ************************************
ok: [localhost] => {
    "msg": "Hello World!"
}

PLAY RECAP **********************************************************
localhost              : ok=2    changed=0    unreachable=0    failed=0   

If you execute it like this, the execution result will come out suddenly. With this, Ansible works for the time being. Easy and convenient.

Related Documents Introduction to Ansible Part 2'Basic Grammar' [Introduction to Ansible Part ③'Inventory'] (https://qiita.com/nouhautayomi/items/d647ec7ad0fa7ea3b51f)
** References ** First Ansible (written by Lorin Hochstein, translated by Ryuji Tamagawa, O'Reilly Japan Co., Ltd.) People inside will teach you what you can do with Ansible