Ansible variables

These variables cannot be set directly by the user; Ansible will always override them to reflect internal state, ansible variables. The name of the collection the task that is executing is a part of. In the format of namespace.

You are reading an unmaintained version of the Ansible documentation. Unmaintained Ansible versions can contain unfixed security vulnerabilities CVE. Please upgrade to a maintained version. See the latest Ansible documentation. While automation exists to make it easier to make things repeatable, all of your systems are likely not exactly alike. On some systems you may want to set some behavior or configuration that is slightly different from others. Also, some of the observed behavior or state of remote systems might need to influence how you configure those systems.

Ansible variables

You can pass host names at the command line, but most Ansible users create inventory files. Your inventory defines the managed nodes you automate, with groups so you can run automation tasks on multiple hosts at the same time. Once your inventory is defined, you use patterns to select the hosts or groups you want Ansible to run against. The simplest inventory is a single file with a list of hosts and groups. Ansible Inventory plugins supports a range of formats and sources to make your inventory flexible and customizable. As your inventory expands, you may need more than a single file to organize your hosts and groups. You can create a directory with multiple inventory files. See Organizing inventory in a directory. These can use different formats YAML, ini, and so on. You can pull inventory dynamically. For example, you can use a dynamic inventory plugin to list resources in one or more cloud providers. See Working with dynamic inventory. You can use multiple sources for inventory, including both dynamic inventory and static files. See Passing multiple inventory sources. Inventory basics: formats, hosts, and groups.

You can reference the model of the first disk in the facts shown above in a template or playbook as:. Variables can be defined ansible variables referenced in various ways inside a playbook.

Image by Chuk Yong from Pixabay. When you write an Ansible playbook , you sometimes need to pass data into your play at runtime. To do that, you can use a variable , a sort of placeholder for data that's meant to be determined at some point in the future. There are lots of places to create variables for your playbooks, such as an inventory file, included files, or even dynamically in your playbook itself. However, you can also pass variables in the terminal when you launch your playbook. For example, this simple playbook uses the debug module to print the value of a variable to the terminal:. To define a variable dynamically when you run a playbook, use the --extra-vars option along with the key and value of the variable you want to define.

Ansible is not a full-fledged programming language, but it does have several programming language features, and one of the most important of these is variable substitution. There are different types of variables available in Ansible you can click on individual link which will take you to the respective official documentation page from docs. The following examples are all invalid, however, and cannot be used :. There are two types of variables which you can define in an inventory i. Let us understand about each of them individually:. So here I have defined two custom variables which are applicable only for server2. Now we will use this variable with ansible playbook. I have already explained you about groups in an inventory. So group variables can be assigned to a complete group and all the hosts part of that group instead of individual hosts. To demonstrate the let me modify my inventory file and divide the list of hosts into group.

Ansible variables

Ansible uses variables to manage differences between systems. With Ansible, you can execute tasks and playbooks on multiple different systems with a single command. To represent the variations among those different systems, you can create variables with standard YAML syntax, including lists and dictionaries.

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However, unlike registered variables, facts can be gathered independently and cached for repeated use. Always give descriptive and clear names to your variables. How do I copy files recursively onto a target host? Pre-order now. To retain Ansible facts for repeated use, select a different cache plugin. Anything in the vars directory of the role overrides previous versions of that variable in namespace. These include Playbook Keywords and Python keywords. Ansible has a strict set of rules to create valid variable names. As we have previously seen, the most straightforward way is to define variables in a play with the vars section. YAML also supports dictionaries which map keys to values. Information about Ansible: magic variables. If you are not sure what other variables are defined, and you need a particular value, use --extra-vars -e to override all other variables. Ansible loads every possible variable it finds, then chooses the variable to apply based on variable precedence rules. Connecting to hosts: behavioral inventory parameters.

With Ansible you can retrieve or discover certain variables containing information about your remote systems or about Ansible itself. Variables related to remote systems are called facts. With facts, you can use the behavior or state of one system as a configuration on other systems.

A dictionary is an unordered collection of mutable items where each item is represented as a key-value pair. Select version: latest 2. With Ansible you can retrieve or discover certain variables containing information about your remote systems or about Ansible itself. The playbook file would appear as shown with a single task for creating a new user. We can use the keyword register to create our own custom variables from task output. Author: Randy Romero Red Hat. Adding variables to inventory. You can create a directory with multiple inventory files. If you do not quote the whole expression, the YAML parser cannot interpret the syntax - it might be a variable or it might be the start of a YAML dictionary. The variable is enclosed in a single-quoted string inside a pair of single curly braces.