If you are familiar with Ansible — the amazing configuration management tool but haven’t yet played around Ansible roles, I must tell you that you are missing out the fun.
To help yourself overcome the struggle of managing huge tasks files with variables, handlers and templates, I recommend you reading this till end.
This blog will give a brief introduction to Ansible Roles and walk you through a simple yet elegant demonstration.
Ansible roles is the way you can separate your tasks, variables and related files in a nice file structure. The tasks for the end configuration to achieve is written in a separate file, associated variables in a separate file, the handlers to notify in a separate file and the files to copy in a different file. All of these are isolated but eventually make up a single transferable entity.
This is how the file structure looks like of any role (here ‘miao.emacs’)
In this blog, we will create a role to configure a webserver and subsequently configure a load balancer to balance the load between the web servers.
Note: Update the roles_path variable in your ansible.cfg file to point to the directory where you want to keep your roles.
To begin, create two roles.
ansible-galaxy role init myapache
ansible-galaxy role init myloadbalancer
You will see two folders in your roles_path named ‘myapache’ and ‘myloadbalancer’. You will also see that the file structure inside these is same as shown in Fig 1.
Now, in the myapache/tasks/main.yml file and myloadbalcer/tasks/main.yml, write your tasks.
Here, I am copying a file(index.php) to managed nodes from the controller node, so that has to be kept in the files folder under corresponding role directory.
Similarly, using a jinja template(haproxy.cfg.j2), I am also updating the configuration file of the load balancer. hence, that file must be kept in the templates folder under corresponding role directory.
Also, the handlers are defined in a separate file.
Finally, create a setup.yml file to use the two roles and configure everything in one playbook run.
Doesn’t this look cleaner and readily understandable? Definitely, yes!
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