Install Stuff: The apt Module
Keep on Learning!
If you liked what you've learned so far, dive in! Subscribe to get access to this tutorial plus video, code and script downloads.
Now we are dangerous! With the playbook setup, we can add more and more tasks that
use more and more modules. One of the most useful modules is called apt - our best
friend for installing things via apt-get on Debian or Ubuntu.
We're going to install a really important utility called cowsay. I already have
it installed locally, so let's try it:
cowsay "I <3 Ansible"
OMG!
Tip
If you have cowsay installed locally, make sure to run export ANSIBLE_NOCOWS=1.
Otherwise, Ansible will use cowsay for its output, which is hilarious, but a bit
distracting.
Since this is absolutely necessary on any server that runs MooTube, let's add a second
task to install it. Usually, I give my tasks a bit more structure, with a name that
mentions how important this is. Below, add the module you want to use: apt:
| - hosts: vb | |
| tasks: | |
| - ping: ~ | |
| - name: Install cowsay - it's probably important | |
| apt: | |
| // ... lines 9 - 10 |
If you check out the apt module docs, you'll see that it has an option called
name, which is the package that we want to install. To pass this option to the
module, indent on the next line, and add name: cowsay:
| - hosts: vb | |
| tasks: | |
| - ping: ~ | |
| - name: Install cowsay - it's probably important | |
| apt: | |
| name: cowsay |
Done!
Run the playbook!
ansible-playbook ansible/playbook.yml -i ansible/hosts.ini
sudo: Using become
The ping works, but the install fails! Check out the error:
Could not open lock file. Unable to lock the administration directory, are you root?
Of course! Ansible doesn't automatically run things with sudo. When a task does
need sudo, it needs another option: become: true:
| - hosts: vb | |
| tasks: | |
| // ... lines 5 - 6 | |
| - name: Install cowsay - it's probably important | |
| become: true | |
| apt: | |
| name: cowsay |
This means that we want to become the super user. In our VM, the vagrant user
can sudo without typing their password. But if that's not your situation, you can
configure the password.
Try it again!
ansible-playbook ansible/playbook.yml -i ansible/hosts.ini
This time... it works! And notice, it says "changed" because it did install cowsay.
Now try it again:
ansible-playbook ansible/playbook.yml -i ansible/hosts.ini
Ah, hah! The second time it just says "Ok" with changed=0. Because remember: the
module doesn't just dumbly run apt-get! Its real job is to guarantee that cowsay
is in an installed "state".
Oh, and if you're Googling about Ansible, you might see become: yes. In Ansible,
whenever you need a Boolean value like true or false, Ansible allows you to say
"yes" or "no". Don't get surprised by that: "yes" means true and "no" means false.
Use whichever you like!
Time to get our system setup for real, with PHP, Nginx and other goodies!
Had to run apt-get update in order to get cowsay installed for ubuntu/xenial64