Ansible

Ansible is an automation tool that easens work a lot. I just set it up once and from then on I can forget about configurations and settings for my projects. It's really great for doing repeatable tasks like setting up nginx for subdomains, redeploying django projects, updating the OS, etc.

For example, to set up a script that updates the server:

---

- hosts: my_server
   vars_files:
     - vars.yml
   remote_user: "{{ user }}"
   become: true
   tasks:
       - name: Running update and safe-upgrade
          apt:
              update_cache=yes
              upgrade=dist
          register: result
       - debug: var=result.stdout_lines

I store my variables in the vars.yml file. In the example above, the user variable is found here. The file looks like this:

---

user: thisuser

The my_server variable is set in /etc/ansible/hosts file and looks like this:

[my_server]
random_url.co.ke

Since updating the system requires admin priviledges, make sure the user has those permissions. This is why the script has remote_user and become in its body. Also ansible will need to run with these priviledges, so to do so:

ansible-playbook --ask-become-pass updates.yml

And just like that the system gets updated. This asks for the server password for the elevated user.

Let's say I want to update my nginx config files to enable another subdomain. Ansible should upload my config file to my server and also restart nginx so that these changes are accepted.

---
- hosts: my_server
   vars_files:
     - vars.yml

   tasks:
   # copy project nginx set up to server
     - name: set up nginx config on server
        remote_user: "{{ user }}"
        become: true
        template:
          src=config/nginx.j2
          dest=/etc/nginx/sites-enabled/{{ project_name }}
        notify:
          - restart nginx

   handlers:
     - name: restart nginx
        remote_user: "{{ user }}"
        become: true
        service: name=nginx state=restarted

Since ansible supports jinja templating, the nginx config file is written in this format. Also the variables project_name and user are found from the vars.yml file. What the above does is copy the nginx config file to /etc/nginx/sites-enabled/project_name restarts nginx.

Here is the template used. You can also use variables defined in the vars.yml in the template too, which is really helpful.

server {
#listen 443;
    listen 80;
    server_name {{ server_name }};
    charset utf-8;
    client_max_body_size 2M;

    location / {
        # django
        include proxy_params;
        proxy_pass http://unix:{{ sock_file }};
    }

    location /static {
        autoindex on;
        alias {{ static_root }};
    }

    location /media {
        autoindex on;
        alias {{ media_root }};
    }
}

Some commands can run with ansible-playbook file.yml but others need elevated permissions. To help me deal with this I usually have a Makefile in my ansible playbooks directory. For example to deal with the two configs above, I'd have:

ANSIBLE_SUDO = ansible-playbook --ask-become-pass

update:
    $(ANSIBLE_SUDO) updates.yml

nginx:
    #(ANSIBLE_SUDO) nginx_setup.yml

You can find moer about ansible here