Templates with Jinja2

Part of the Ansible course

Copying a static file to every machine works fine right up until one machine needs a different port number, a different hostname, or a config block that only applies to some servers and not others. At that point you have two bad options: keep a slightly different copy of the file for every machine and hope you remember to update all of them together, or write the file by hand on each server after Ansible finishes.

You have already met the idea of a form letter with blanks in it, filled in per recipient. Jinja2, the templating language Ansible uses, is that same idea taken further. A basic mail merge only fills in blanks: a name here, an address there. Jinja2 templates can also decide, line by line, whether a paragraph should appear at all, and they can repeat a line once for every item in a list without you writing that line...