While control structures influence the flow of template processing, another tool exists to modify the contents of a variable. This tool is called a filter. Filters are like small functions, or methods, that can be run on the variable. Some filters operate without arguments, some take optional arguments, and some require arguments. Filters can be chained together as well, where the result of one filter action is fed into the next filter and the next. Jinja2 comes with many built-in filters, and Ansible extends these with many custom filters available to you when using Jinja2 within templates, tasks, or any other place Ansible allows templating.
A filter is applied to a variable by way of the pipe symbol (|), followed by the name of the filter and then any arguments for the filter inside parentheses. There can be a space between the variable name and the pipe symbol, as well as a space between the pipe symbol and the filter name. For example, if we wanted to apply the...