Book Image

Practical Ansible 2

By : Daniel Oh, James Freeman, Fabio Alessandro Locati
Book Image

Practical Ansible 2

By: Daniel Oh, James Freeman, Fabio Alessandro Locati

Overview of this book

Ansible enables you to automate software provisioning, configuration management, and application roll-outs, and can be used as a deployment and orchestration tool. While Ansible provides simple yet powerful features to automate multi-layer environments using agentless communication, it can also solve other critical IT challenges, such as ensuring continuous integration and continuous deployment (CI/CD) with zero downtime. In this book, you'll work with Ansible 2.9 and learn to solve complex issues quickly with the help of task-oriented scenarios. You'll start by installing and configuring Ansible on Linux and macOS to automate monotonous and repetitive IT tasks and get to grips with concepts such as playbooks, inventories, and network modules. As you progress, you'll gain insight into the YAML syntax and learn how to port between Ansible versions. In addition to this, you'll also understand how Ansible enables you to orchestrate multi-layer environments such as networks, containers, and the cloud. By the end of this Ansible book, you'll be well - versed in writing playbooks and other related Ansible code to overcome just about all of your IT challenges, from infrastructure-as-code provisioning to application deployments, and even handling the mundane day-to-day maintenance tasks that take up so much valuable time.
Table of Contents (18 chapters)
Section 1: Learning the Fundamentals of Ansible
Section 2: Expanding the Capabilities of Ansible
Section 3: Using Ansible in an Enterprise

Passing working variables via the CLI

One thing that can help during debugging, and definitely helps for code reusability, is passing variables to playbooks via the command line. Every time your application either an Ansible playbook or any kind of application receives an input from a third party (a human, in this case), it should ensure that the value is reasonable. An example of this would be to check that the variable has been set and therefore is not an empty string. This is a security golden rule, but should also be applied when the user is trusted since the user might mistype the variable name. The application should identify this and protect the whole system by protecting itself. Follow these steps:

  1. The first thing we want to have is a simple playbook that prints the content of a variable. Let's create a playbook called printvar.yaml that contains...