Nested templates

You can include other templates in your templates by using the built-in Tiller::render helper module. For example, if you have a template called main.erb, you can include another template called sub.erb by calling this module inside main.erb:

This is the main.erb template. 
This will include the sub.erb template below this line:
<%= Tiller::render('sub.erb') -%>

You can nest sub-templates as deeply as you wish, so you can have sub-templates including another sub-template and so on. However, it is important to note that all variables for sub-templates are evaluated only at the level of the top-level template.

Therefore, trying to pass a variable to the sub-template by putting something like this in your common.yaml will not work:

    sub_var: This is a var for the sub-template

You will not be able to access sub_var from your template - you will need to declare it in the main.erb block instead, where it will be available to all sub-templates.