Category Archives: ansible

ansible, linux

Ansible: Simple template example within a role

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Here, we create a role which a) deploys a file into /tmp and b) demonstrates the use of a host variable to modify the contents of this file. As the contents is dynamic we use the ‘template’ module, rather than file.

Using Ansible Galaxy we create the role directory structure:-

steve@devbox:~$ cd ~ansible/roles
steve@devbox:~/ansible/roles$ ansible-galaxy init testtmp
- testtmp was created successfully

Let’s go ahead and create our template file:-

steve@devbox:~/ansible/roles$ cd testtmp/templates
steve@devbox:~/ansible/roles/testtmp/templates$ vi tmp.conf

Swap Free = {{ ansible_swapfree_mb }}

The {{ ansible_swapfree_mb }} indicates a variable (in this case, a host fact).

Now create a simple task top deploy the above template:-

steve@devbox:~/ansible/roles/testtmp/templates$ cd ../tasks/
steve@devbox:~/ansible/roles/testtmp/tasks$ vi main.yml 

---
# tasks file for testtmp
- name: Drop template into /tmp
  template: src=~/ansible/roles/testtmp/templates/tmp.conf dest=/tmp/tmp.txt

We now modify (or create) our site.yml:-

steve@devbox:~/ansible/roles/testtmp/tasks$ cd ~/ansible/
steve@devbox:~/ansible$ ls
roles  site.yml
steve@devbox:~/ansible$ vi site.yml 

---
- name: Deploy test roles
  hosts: all
  become: true

  roles:
    - time
    - testtmp

Now let’s run the playbook:-

steve@devbox:~/ansible$ ansible-playbook site.yml

PLAY [test ntp via time role] **************************************************

TASK [setup] *******************************************************************
ok: [172.0.0.1]

TASK [time : Install NTP] ******************************************************
ok: [172.0.0.1]

TASK [testtmp : Drop template into /tmp] ***************************************
changed: [172.0.0.1]

PLAY RECAP *********************************************************************
172.0.0.1                  : ok=3    changed=1    unreachable=0    failed=0

Success! Let’s hit the target and check the actual changes:-

steve@devbox:~/ansible$ ssh 172.0.0.1
...
Last login: Tue Nov 22 12:55:29 2016 from 172.0.0.2
steve@testtarget:~$ ls -l /tmp
total 4
-rw-r--r-- 1 root root 17 Nov 22 12:55 tmp.txt
steve@testtarget:~$ cat /tmp/tmp.txt 
Swap Free = 767

Yes! The template is deployed and the variable is set correctly.

ansible, linux

Ansible: From install to roles in 5 minutes

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Here’s a real quick walkthrough from install of Ansible to a primitive role based playbook.

Install ansible and create/edit our ansible hosts file:-

steve@devbox:~$ sudo aptitude install ansible
steve@devbox:~$ sudo vi /etc/ansible/hosts

[test]
172.0.0.1

In my case I have a single target in the ‘test’ group:-

I copy my private key to the remote system (authorized_keys) ensuring permissions are correct.
We should then be able to do an ansible ping. Be aware you will need python installed on the target.

steve@devbox:~$ ansible -m ping all
172.0.0.1 | SUCCESS => {
    "changed": false, 
    "ping": "pong"
}

Now I make a basic directory structure to store our yaml files.

steve@devbox:~$ mkdir ansible/roles
steve@devbox:~$ cd ansible/roles

ansible-galaxy can help us with the layout of the role directory structure:-

steve@devbox:~$ ansible-galaxy init time
- time was created successfully

Let’s take a look at what ansible-galaxy has created for us:-

steve@devbox:~$ cd time; ls
defaults  files  handlers  meta  README.md  tasks  templates  tests  vars

Great stuff. Let’s start by creating a task. I’d like to install NTP and ensure it’s running.

steve@devbox:~$ cd tasks
steve@devbox:~$ vi main.yml

---
# tasks file for time
- name: Install NTP
  apt: pkg=ntp state=installed update_cache=true
  notify: start ntp

The above includes a ‘notify’ for a handler to take action. Let’s create that handler:-

steve@devbox:~$ cd ../handlers
steve@devbox:~$ vi main.yml

---
# handlers file for time
- name: start ntp
  service: name=ntp state=started

Now move back to the root of our ansible configs and create a simple playbook (site.yml)

steve@devbox:~$ cd ~/ansible
steve@devbox:~$ vi site.yml

---

- name: test ntp via time role
  hosts: all
  become: true

  roles: 
    - time

The above indicates we want all hosts to include the NTP role. We’ll need to ‘become root’ on the target in order to install software. The role we want to run is called ‘time’ (as per the ansible-galaxy init and our resultant direcctory structure).

Finally, let’s run the site playbook:-

steve@devbox:~$ ansible-playbook site.yaml

PLAY [test ntp via time role] **************************************************

TASK [setup] *******************************************************************
ok: [172.0.0.1]

TASK [time : Install NTP] ******************************************************
changed: [172.0.0.1]

RUNNING HANDLER [time : start ntp] *********************************************
ok: [172.0.0.1]

PLAY RECAP *********************************************************************
172.0.0.1                  : ok=3    changed=1    unreachable=0    failed=0

Success!