How to install software packages with an Ansible playbook

Ansible is a popular automation tool used by sysadmins and developers to get computers in a specific state. Ansible modules are, in a way, what commands are to a Linux computer. They provide solutions to specific problems, and one common task when maintaining computers is keeping them updated and consistent. In this article, I show you how to install software packages with Ansible.

Requirements

To run Ansible ad hoc commands and playbooks on managed nodes, a remote user with SSH access is needed on each managed node. For this example, I'll call that user tux. Tux needs permission to run commands with elevated privileges to install packages. Therefore the file /etc/sudoers.d/tux with the following content must exist on all managed nodes:

tux ALL=(ALL) NOPASSWD:ALL

Use visudo to edit the /etc/sudoers file entries.

Package installation

Suppose you've found a cool new package called sysstat that you now want to install on all your hosts at once. That's an easy job for Ansible:

$ ansible all --user tux --become \
--module-name dnf -a’name=sysstat state=latest’

And you're done. 

[ You might also like: How to create an Ansible Playbook ]

That one line is called an Ansible ad hoc command. These are usually one-time tasks that you don't expect to repeat. However, in the interest of reusability, it’s better to put such instructions into an Ansible playbook, like this:

---
- hosts: all
  tasks:
  - name: Make sure the current version of ‘sysstat’ is installed.
    dnf:
      name: sysstat
      state: latest

Save this playbook to a file called install_packages.yml, and then you can run it with the following command:

$ ansible-playbook -u tux -b install_packages.yml

You can put it on a schedule with cron, making sure the desired package gets installed and reinstalled if someone removes it.

Install several packages

What if you want to install a list of packages on all of your hosts? That's easy, too:

---
- hosts: all
  tasks:
  - name: Package installation
    dnf:
      name:
        - sysstat
        - httpd
        - mariadb-server
      state: latest

Run the playbook:

$ ansible-playbook -u tux -b install_packages.yml

I'm sure you get the idea. Need more packages? Just add them to the list.

Wrap up

Managing software with Ansible is pretty straightforward. You can use the DNF module to manage the actual installation and a YAML-based Ansible playbook to distribute the installation instructions to your managed nodes. This is another excellent example of how Ansible makes life easier for sysadmins who manage many systems.

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