Preliminaries

Objectives

We will learn how to:

Prerequisites

We assume that Rougail’s library is installed on your computer.

Making a structure file

The folder structure

Here is the tree structure we want to have:

workplace
├── firefox
│   └── struct.yml

  • Let’s make a workplace directory, with a firefox subfolder.

  • First, we wil make a structure file, so let’s create a struct.yml file located in the firefox subfolder.

An empty structure file

This is an empty Rougail structure description file.

An empty rougail dictionnary file with the version number only
---
version: 1.1

Defining a variable and its default value

a first variable

Let’s put a variable in the Rougail structure description file

This is a first Rougail variable in a Rougail dictionnary:

A Rougail dictionnary file with only one variable
---
proxy_mode:

  • If we run the Rougail CLI utility command

 rougail -v 1.1 -m firefox/

we will actually have an error:

🛑 ERRORS
┣━━ The following variables are mandatory but have no value:
┗━━   - proxy_mode

Because this variable is mandatory and needs to be set but there’s no value yet.

We can therefore deduce this result:

Note

Once defined, an option configuration value is mandatory.

Rougail waits for the proxy_mode configuration option’s value to be set.

See also

To go further, have a look at the mandatory option according to the definition of Tiramisu.

mandatory

A variable is mandatory when a value is required, that is, None is not a possible value. It must have a defined value.

Let’s add a variable’s description, which is not mandatory but which is a good practice:

A Rougail dictionnary file with a variable and a description
---
proxy_mode:
  description: Configure Proxy Access to the Internet

how to set a value – the default value

We need to set a value to this proxy_mode variable. A first way to do it is to set a value by default.

default value

A default value is a variable value that is predefined, that is, this value is placed right in the structure file.

So let’s define a variable with a description – and a default value

A rougail dictionnary file with a default value for the variable
---
proxy_mode:
  description: Configure Proxy Access to the Internet
  default: No proxy

how to set a value – the assignment

A default value has been set, great. Now how do I assign a value to a variable?

How to set a value

So far we have only talked about the one that writes the structure files. It’s role is called the integrator’s role.

integrator

An integrator in the Rougail field is the person who writes the structure files. He has the responsibilité of the integration process, that is, defines the variables and the relationship between them, the variables that are allowed (or not) to be set, and so on. His responsabilites are the structuration and the consistency of the variables.

Now we will talk about the one that defines the values. It is called the operator.

operator

An operator in the Rougail field is the person who assigns values to the pre-defined variables, his responsabilities are to set variable values correctly.

The user values, that is the values that have been set by the operator, are of course type validated. The type validation is driven by the definitions in the structure file.

Values are mandatory

It is the operator’s responsibility to set the user datas variables values. The operator does not handle the structure files, he is responsible of other files called the user data files.

user datas

User datas, as opposed to structured datas, are datas that only concern the assignment of values and not the consistency of the variables.

The variable’s values are also called user values.

The consistency field is outside of the user datas scope. The consistency is handled in the structured datas‘s scope.

Folder structure update

Now we add a config/config.yml file in our project:

workplace
├── firefox
│   ├── struct.yml
└── config
    └── config.yml

how to set a value in a user datas file

So for example if the integrator has not set any default value in his structure file, the operator can do it like this:

A Rougail user datas file config/config.yml, with a default value set.
---
proxy_mode: No proxy

With the rougail CLI the operator has to add the -u file -ff config/config.yml options:

A rougail Command Line Utility call with the config/config.yml Rougail user datas file
rougail -v 1.1 -m firefox -u file -ff config/01/config.yaml

Let us clarify this essential point:

  • the integrator works on structure files

  • the operator works on user data files

Note

Most of the time, the integrator and the operator are one and the same person, here we are talking about roles and not necessarily about people.

Variable’s type

type inference

If the type attribute is not set, Rougail infers a string type for the proxy_mode configuration option variable type as defined in the structure file.

type setting

If the operator sets an option value for example with the number type, like this:

---
example_var:
  description: Configure Proxy Access to the Internet
  type: number

Then Rougail will expect a int or a float as a value for the example_var variable.

Defining a choice type

In our firefox use case, the real type of the proxy_mode variable will be now set as a choice type:

choice type

A choice type variable is a variable where the content is constrained by a list

The real firefox/proxy.yml Rougail dictionnary file with a choice type
 1---
 2proxy_mode:
 3  description: Configure Proxy Access to the Internet
 4  type: choice
 5  choices:
 6    - No proxy
 7    - Auto-detect proxy settings for this network
 8    - Use system proxy settings
 9    - Manual proxy configuration
10    - Automatic proxy configuration URL
11  default: No proxy

  • Let’s run the Rougail CLI

 rougail -v 1.1 -m firefox/

We have an output like this one:

╭────────────────────────── Caption ──────────────────────────╮
│ Variable                           Default value            │
│ Undocumented variable              Modified value           │
│ Undocumented but modified variable (Original default value) │
│ Unmodifiable variable                                       │
╰─────────────────────────────────────────────────────────────╯
Variables:
┗━━ 📓 proxy_mode: No proxy

The proxy_mode variable here, implicitely requires a value. It is a mandatory variable.

As we set the proxy_mode variable as No proxy by default, we actually have specified a value, and the value appears in yellow, which means : “set by default”.

Container type

We say that the proxy_mode variable is constrained (by the choice type).

We have the list of the possible (authorized) values:

  • No proxy

  • Auto-detect proxy settings for this network

  • Use system proxy settings

  • Manual proxy configuration

  • Automatic proxy configuration URL

choice type

The proxy_mode setting is “choice” (type: choice) means that there is a list of available values that can be selected.

Key points progress

Indeed, in the Firefox configuration, it is possible to define several configuration modes, from no proxy at all (no proxy) to a kind of automatic configuration mode from a file (set up proxy configuration from a file).

Keywords

  • structure file: structure description file

  • variable: an option’s name which has a value

  • a variable’s description

  • a variable’s type

  • a variable’s default value

  • the integrator and operator roles

  • a mandatory value

  • a choice type

Progress

To sum up, we have arrived at this point in writing a structure file like this:

Structure description file

A Rougail dictionnary file with a variable named proxy_mode, with a default value.
 1---
 2proxy_mode:
 3  description: Configure Proxy Access to the Internet
 4  type: choice
 5  choices:
 6    - No proxy
 7    - Auto-detect proxy settings for this network
 8    - Use system proxy settings
 9    - Manual proxy configuration
10    - Automatic proxy configuration URL
11  default: No proxy