A dynamic family

Objectives

In this section we will learn how to create a dynamically created family.

Reminder

We handled the HTTPS mode in the previous section. But there’s more. Let’s have a look at the firefox’s configuration page:

In fact we shall not only handle the HTTPS configuration but the SOCKS configuration too. And we can see that these two group of variables are very similar: they both have two variables, that is a host and a port.

Creating a generic family

There are two proxies that are to be configured :

• the HTTP proxy

• the SOCKS proxy

It’s not the place here to describe what the HTTP and SOCKS protocols are. The interesting point is that :

• they are similar in terms of our firefox’s configuration

• we can use a generic family declaration mode in this use case (we call this genericity “dynamic creation”)

Instead of doing something like this:

https_proxy:
  description: HTTPS Proxy
  ...

  address:
    description: HTTPS address
    ...

  port:
    description: HTTPS Port
    ...

And this:

sock_proxy:
  description: SOCKS Proxy
  ...

  address:
    description: SOCKS address
    ...

  port:
    description: SOCKS Port
    ...

With Rougail we have the ability to say this:

firefox/20-proxy.yml

---
manual:

  use_for_https:
    description: Also use this proxy for HTTPS
    default: true

  "{{ identifier }}_proxy":
    description: "{{ identifier }} Proxy"
    dynamic:
      - HTTPS
      - SOCKS
    hidden:
      variable: manual.use_for_https

    address:
      description: "{{ identifier }} address"
      default:
        variable: manual.http_proxy.address

    port:
      description: "{{ identifier }} port"
      default:
        variable: manual.http_proxy.port

What is an identifier?

We define what we call an identifier, which is a local variable, used only for creating multiple families at one time (that is, being more generic in our declaration style). This is this syntax that allows the declaration of multiple families at one time:

"{{ identifier }}_proxy":
  description: "{{ identifier }} Proxy"
  dynamic:
    - HTTPS
    - SOCKS

This identifier is a parameter that enables us to create two families named https_proxy and socks_proxy.

Note

The declaration syntax is a jinja templating syntax, which is commonly used in the python coding field.

So yes, we have gained in genericity but we have lost in readability, you would say. But we haven’t just been generic. We now have the ability to create conditional hidden family (and not only conditionnal hidden variables like we did earlier).

A conditional hidden family with jinja