Introduction to Ad-Hoc Commands

An Ansible ad-hoc command uses the command-line tool ansible to automate a single task on one or more nodes. An ad-hoc command looks like this:

Ad-hoc commands offer a quick and easy way to execute automation, but they are not built for reusability. Their advantages are that they leverage Ansible modules which are idempotent, and the knowledge gained by using them directly ports over to the Ansible playbook language.

The importance of idempotence

Why not script it? Why not just write your own automation using PowerShell, Bash, or Python? The short answer is idempotence.

Using an imperative language, you are writing a prescriptive order of operations that do not account for all the various scenarios that might be true.

For example, take the task of creating a directory. This is accomplished by running a single command.

Problem

What happens when you rerun the command? You get an error stating that the directory exists.

Solution

That’s easy enough to address. Add a try-catch block to account for this scenario.

However, what if you want to modify the permissions? Each new situation requires that you reevaluate the automation and add additional logic.

You want a way to declare the end state and have the automation handle the rest.

Idempotent automation

Ansible uses a declarative language that ...