Learning Ansible basics

Ansible® is an open source IT automation engine that automates provisioning, configuration management, application deployment, orchestration, and many other IT processes.

Ansible can be used to install software, automate daily tasks, provision infrastructure and network components, improve security and compliance, patch systems, and orchestrate complex workflows.

Red Hat® Ansible Automation Platform is built on the same fundamentals as the community version of Ansible, but it provides full enterprise life cycle support and includes features designed to help organizations standardize, operationalize, and scale automation. 

This article will explain the basics that drive both community Ansible and Ansible Automation Platform.

Modules

Ansible works by connecting to nodes (or hosts) and pushing out small programs—called modules—to these nodes. Nodes are the target endpoints—servers, network devices, or any computer—that you aim to manage with Ansible. Modules are used to accomplish automation tasks in Ansible. These programs are written to be resource models of the desired state of the system. Ansible then executes these modules and removes them when finished.

Without modules, you’d have to rely on ad-hoc commands and scripting to accomplish tasks. Ansible contains built-in modules that you can use to automate tasks, or you can write new ones on your own. Ansible modules can be written in any language that can return JSON, such as Ruby, Python, or bash. Windows automation modules can even be written in Powershell. 

Agentless automation 

Ansible is agentless, which means the nodes it manages do not require any software to be installed on them. Ansible reads information about which machines you want to manage from your inventory. Ansible has a default inventory file, but you can create your own and define which servers you want to be managed. 

Ansible uses SSH protocol to connect to servers and run tasks. By default, Ansible uses SSH keys with ssh-agent and connects to remote machines using your current user name. Root logins are not required. You can log in as any user, and then use su or sudo commands as any user.

Once it has connected, Ansible transfers the modules required by your command or Ansible Playbook to the remote machine(s) for execution. Ansible uses human-readable YAML templates so users can program repetitive tasks to happen automatically without having to learn an advanced programming language.

Using Ansible for ad-hoc commands 

You can also use Ansible to run ad-hoc commands, which automate a single task on one or more managed nodes. To do this, you will need to run a command or call a module directly from the command line. No playbook is used, and ad-hoc commands are not reusable. This is fine for a one-time task, but anything more frequent or complex will require the use of an Ansible Playbook.

Ansible Playbooks are used to orchestrate IT processes. A playbook is a YAML file—which uses a .yml or .yaml extension—containing 1 or more plays, and is used to define the desired state of a system. This differs from an Ansible module, which is a standalone script that can be used inside an Ansible Playbook. 

Plays consist of an ordered set of tasks to execute against host selections from your Ansible inventory file. Tasks are the pieces that make up a play and call Ansible modules. In a play, tasks are executed in the order in which they are written.

When Ansible runs, it can keep track of the state of the system. If Ansible scans a system and finds the playbook description of a system and the actual system state don't agree, then Ansible will make whatever changes are necessary for the system to match the playbook. 

Ansible includes a check mode which allows you to validate playbooks and ad-hoc commands before making any state changes on a system. This shows you what Ansible would do, without actually making any changes. Handlers in Ansible are used to run a specific task only after a change has been made to the system. They are triggered by tasks and run once, at the end of all of the other plays in the playbook.

Variables enable you to alter how playbooks run to manage differences between systems, such as package versions or file paths. With Ansible, you can use a single command to execute playbooks across different systems. Variables account for the variations between these systems, and can be defined in playbooks, inventory, reusable files or roles, or at the command line. Variables follow variable precedence, which defines the order in which variables will override each other.

Ansible Roles are a special kind of playbook that are fully self-contained and portable groupings of tasks, variables, configuration templates, and other supporting files that are needed to complete a complex orchestration. Multiple roles can exist inside a collection, which allow content to be easily shared via Automation Hub and Ansible Galaxy.

Collections are a distribution format for Ansible content that can include playbooks, roles, modules, plugins, and documentation all in one bundle, making it easier for creators to share automation and use content created by others. These collections are sorted by content domain and require less upfront work to find and assemble different roles and modules.

Ansible Content Collections function in the same way, but are specifically designed to help Ansible Automation Platform users automate faster with prebuilt content from Red Hat and our certified partners. These collections—which include both Red Hat Ansible Certified Content and Ansible validated content—are developed and tested with partner input to ensure that they are security-focused, reliable, and enterprise-ready.

Ansible is free to use, download, and modify—and the project benefits from the experience and intelligence of its thousands of contributors. The community distribution of Ansible contains a suite of powerful command line tools supported on most operating systems with Python installed. This includes Red Hat Enterprise Linux®, Debian, Ubuntu, MacOS, FreeBSD, Microsoft Windows, and more. 

Ansible Automation Platform combines more than a dozen upstream projects into a unified, security-hardened enterprise product. It builds on the foundations of community Ansible to create an end-to-end automation experience aimed at cross-functional teams—while providing a plug-and-play experience between automation developers, engineers, and operations teams.

Red Hat Ansible Automation Platform includes all the tools you need to implement enterprise-wide automation, including an event-driven solution, playbooks, and analytics. It allows you to centralize and control your IT infrastructure with a visual dashboard, role-based access control, and more features designed to reduce operational complexity.

With a Red Hat subscription, you get certified content from our robust partner ecosystem, access to hosted management services, and life cycle technical support that allows your teams to create, manage, and scale automation across your organization. And you’ll get expert knowledge gained from our success with thousands of customers.

Organizations not only need the ability to easily create automation, but they also need to be able to share and reuse automation across projects and teams with the right level of governance and control. With Ansible Automation Platform, you can deploy new applications and services faster, manage IT infrastructure more efficiently, and increase application development productivity.