Getting Started with Ansible 16 - Templates

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Overview

Ansible is an incredible configuration management and provisioning utility that enables you to automate all the things. In this series, you'll learn everything you need to know in order to use Ansible for your day-to-day administration duties.

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Location of OpenSSH daemon config file (used as an example for the template)

 /etc/ssh/sshd_config

In the role directory

Create the directory for templates:

 mkdir templates

Copy the sshd config file from a server to this directory with the *.j2 extension:

 sshd_config_ubuntu.j2

Note: "ubuntu" is included in the name, because if you use more than one distro, it's a good idea to start creating the template based on an existing file. Each distro has different paths, so DON'T use the same template for all distributions!

Adding a variable inside the OpenSSH config file template

Inside the template(s), add:

 AllowUsers Template:Ssh users

Note: Make sure the "AllowUsers" option isn't already in the file, if so, replace it with the above)

Adding the variable to a host

Inside the host_vars directory, we should already have a hosts variable file for each server. Add the new variable inside the file(s):

 ssh_users: "jay simone"
 ssh_template_file: sshd_config_ubuntu.j2

Note: Make sure you change the usernames in the ssh_users variable to be the actual usernames you're using for yourself as well as the ansible user.

Having Ansible render the template

Inside the base role, in the main.yml file, add this play:

 - name: openssh | generate sshd_config file from template
   tags: ssh
   template:
     src: "Template:Ssh template file"
     dest: /etc/ssh/sshd_config
     owner: root
     group: root
     mode: 0644
   notify: restart_sshd

Create a handler to restart the OpenSSH daemon

Inside the base role, create a directory for handlers:

 mkdir handlers

Go inside that directory, and create a 'main.yml' file:

 cd handlers
 vim main.yml
 - name: restart_sshd
   service:
     name: sshd
     state: restarted

Run the playbook

 ansible-playbook site.yml

Adding a default value to the variable

In the template, change the "AllowUsers" line to:

 AllowUsers Template:Ssh users

Taking it a bit further, add another variable to the template to determine whether or not password authentication is allowed for a host:

 PasswordAuthentication Template:Passwd auth

Note: Be sure to add the new PasswordAuthentication variable to your host_vars files.