rougail/docs/tutorial/jinja.rst
2026-02-12 11:12:22 +01:00

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Playing with Jinja
====================
.. objectives:: Objectives
In this section we will learn how to create new ways of calculation.
Up to now, our only way of dynamically (that is, during the runtime) calculating
a value is to point on another variable's value. But this is not the only way.
We will learn how to insert `Jinja templating language <https://jinja.palletsprojects.com/en/stable/>`_ into our structure files.
Please note that we do not intend to template our YAML files.
That is a completely different activity.
We will simply insert YAML code to calculate variable, property, or parameter values.
.. prerequisites:: Prerequisites
- We assume that Rougail's library is :ref:`installed <installation>` on your computer.
- It is possible to retrieve the current state of the various Rougail files manipulated in this tutorial step
by checking out the corresponding tag of the `rougail-tutorials` git repository.
Each tag corresponds to a stage of progress in the tutorial.
Of course, you can also decide to copy/paste or download the tutorial files contents while following the tutorial steps.
If you want to follow this tutorial with the help of the corresponding :tutorial:`rougail-tutorials git repository <src/branch/1.1>`,
this workshop page corresponds to the tags :tutorial:`v1.1_070 <src/tag/v1.1_070>` to :tutorial:`v1.1_072 <src/tag/v1.1_072>`
in the repository.
::
git clone https://forge.cloud.silique.fr/stove/rougail-tutorials.git
git switch --detach v1.1_070
A conditional hidden family with Jinja
---------------------------------------
Let's show add some jinja code in our structure file:
.. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_070/firefox/20-manual.yml
:language: yaml
:caption: The :file:`firefox/20-manual.yml` structure file with some `jinja` code in the `hidden` property
..
%YAML 1.2
---
version: 1.1
manual:
use_for_https: true # Also use this proxy for HTTPS
'{{ identifier }}_proxy':
description: '{{ identifier }} Proxy'
hidden:
jinja: |-
{% if _.use_for_https %}
HTTPS is same has HTTP
{% endif %}
dynamic:
- HTTPS
- SOCKS
address:
description: '{{ identifier }} address'
default:
variable: __.http_proxy.address
port:
description: '{{ identifier }} port'
default:
variable: __.http_proxy.port
version:
description: SOCKS host version used by proxy
choices:
- v4
- v5
default: v5
disabled:
type: identifier
when: HTTPS
...
If we set the `use_for_https` to `false`:
.. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_070/config/01/config.yml
:language: yaml
:caption: FIXME
..
---
proxy_mode: Manual proxy configuration
manual:
http_proxy:
address: http.proxy.net
port: 3128
use_for_https: false
https_proxy:
address: https.proxy.net
Nothing special appears when we launch the Rougail CLI:
.. raw:: html
:url: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_070/config/01/cmd_ro.txt
:class: terminal
..
rougail -m firefox/ -u yaml -yf config/01/config.The
---
..
env ROUGAIL_MANUAL.USE_FOR_HTTPS=true
::
rougail -m firefox/ -u yaml -yf config/01/config.yml --cli.root manual.https_proxy
we have a warning:
::
🔔 Warning
┗━━ Manual proxy configuration
┗━━ HTTPS Proxy
┗━━ HTTPS address: 🔔 family "HTTPS Proxy" has property hidden, so
cannot access to "HTTPS address", it will be ignored when loading
from the YAML file "config/01/config.yml"
╭────────────── Caption ──────────────╮
│ Unmodifiable variable Default value │
╰─────────────────────────────────────╯
Variables:
┣━━ 📓 HTTPS address: http.proxy.net
┗━━ 📓 HTTPS port: 3128
It is interesting here to launch the Rougail CLI in the :term:`read write mode`:
..
env ROUGAIL_MANUAL.USE_FOR_HTTPS=true
::
rougail -m firefox/ --cli.root manual.https_proxy -u yaml environment -yf config/01/config.yml --cli.read_write
.. code-block:: bash
ERROR: cannot access to optiondescription "HTTPS Proxy"
because has property "hidden"
(HTTPS is same has HTTP)
yml standard output:
.. raw:: html
:url: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_070/config/01/output_ro.html
:class: output
..
Variables:
┣━━ 📓 Configure Proxy Access to the Internet: Manual proxy configuration ◀ loaded from the YAML file "config/01/config.yml" (⏳ No proxy)
┗━━ 📂 Manual proxy configuration
┣━━ 📂 HTTP Proxy
┃ ┣━━ 📓 HTTP address: http.proxy.net ◀ loaded from the YAML file "config/01/config.yml"
┃ ┗━━ 📓 HTTP Port: 3128 ◀ loaded from the YAML file "config/01/config.yml" (⏳ 8080)
┣━━ 📓 Also use this proxy for HTTPS: false ◀ loaded from the YAML file "config/01/config.yml" (⏳ true)
┣━━ 📂 HTTPS Proxy
┃ ┣━━ 📓 HTTPS address: https.proxy.net ◀ loaded from the YAML file "config/01/config.yml" (⏳ http.proxy.net)
┃ ┗━━ 📓 HTTPS port: 3128
┗━━ 📂 SOCKS Proxy
┣━━ 📓 SOCKS address: http.proxy.net
┣━━ 📓 SOCKS port: 3128
┗━━ 📓 SOCKS host version used by proxy: v5
We can hide or disable some variables or families with other techniques than
pointing on a variable's value.
Let's reason on the previous HTTPS proxy configuration's manual mode:
.. code-block:: yaml
manual:
use_for_https:
description: Also use this proxy for HTTPS
default: true
https_proxy:
type: family
description: HTTPS Proxy
hidden:
variable: manual.use_for_https
This is extracted from the proxy's manual configuration we discussed before.
We see here that there is an `https_proxy` family that is going to be hidden
depending on the value of another variable:
.. code-block:: yaml
https_proxy:
type: family
hidden:
variable: manual.use_for_https
Now we could write it like that:
.. code-block:: yaml
manual:
use_for_https:
description: Also use this proxy for HTTPS
default: true
https_proxy:
description: HTTPS Proxy
type: family
hidden:
type: jinja
jinja: |
{% if rougail.manual.use_for_https %}
the HTTPS Proxy family is hidden
{% endif %}
Yes, it's done in a more complicated (but more powerful) way.
Let's explain this a little:
We have replaced this simple hidden property declaration:
.. code-block:: yaml
hidden:
variable: manual.use_for_https
by this (more complicated) hidden property declaration:
.. code-block:: yaml
hidden:
type: jinja
jinja: |
{% if rougail.manual.use_for_https %}
the HTTPS Proxy family is hidden
{% endif %}
The fact is that it has same result, but here we have more possibilities.
The hidden process is done by a calculation.
Another jinja calculation type sample
---------------------------------------
We can now hide or disable some variables or families with other techniques than
pointing on a variable's value.
Let's reason upon the proxy's manual configuration we discussed before.
We have the :file:`dict/02-proxy_manual.yml` structure file:
.. code-block:: yaml
:caption: the :file:`structfile/02-proxy_manual.yml` file
---
version: '1.1'
manual:
description: Manual proxy configuration
type: family
disabled:
type: jinja
jinja: |
{% if rougail.proxy.proxy_mode != 'Manual proxy configuration' %}
the proxy mode is not manual
{% endif %}
.. questions:: Question
**question**: OK then. What happens when you select the "Manual proxy configuration"?
Here if the user selects the "Manual proxy configuration" proxy mode,
the the `manual` family will be disabled. This is what the jinja code says.
Let's explain it more precisely.
.. note:: The "the proxy mode is not manual" output is be used in the log outputs
for example while
Why Jinja?
---------------
.. questions:: What about this `Jinja` type?
If the :term:`Jinja` template returns some text, then the family will be `disabled`. Otherwise it is accessible.
Deactivating a family means that we will not be able to access it as well as the variables or families included in this family.
.. note:: If the Jinja template does not return any text, the variable will be **enabled**.
Here we are using the Jinja condition statement.
.. glossary::
Jinja
`Jinja <https://jinja.palletsprojects.com>`_ is a template engine.
we are using Jinja in a classical way, that is, Jinja allows us to handle different cases,
for example with the `if` statement.
What can be calculated?
---------------------------
We have seen that the `disabled` or `hidden` properties could be calculated.
The default values can be calculated too.
.. todo:: montrer un exemple de valeur par défaut calculées (type jinja)
.. todo:: montrer aussi ici des exemples de calculs de valeurs variables, ce qui est un des usages principaux de jinja
Using jinja in a dynamic family declaration
-----------------------------------------------
Let's come back to the previous section's FIXME `dynamic family example <conditional_hidden_family>`
In a dynamic family, as seen before, you have the possibility to name your identifier. In the classic declaration,
the identifier's variable is named "identifier" by default. Sounds logical:
.. code-block:: yaml
"{{ identifier }}_proxy":
description: "{{ identifier }} Proxy"
dynamic:
- HTTPS
- SOCKS
Here the identifer's variable takes the value of the `dynamic` family parameter.
.. type-along:: Using a jinja calculation with a parameter
We have the possibility to use a given variable variable inside a jinja calculation:
.. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/tag/v1.1_050/firefox/20-manual.yml
:language: yaml
:caption: 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:
jinja: |
{% if my_identifier == 'HTTPS' and manual.use_for_https %}
HTTPS is same has HTTP
{% endif %}
params:
my_identifier:
type: identifier
description: |
in HTTPS case if "manual.use_for_https" is set to True
address:
description: "{{ identifier }} address"
default:
variable: manual.http_proxy.address
port:
description: "{{ identifier }} port"
default:
variable: manual.http_proxy.port
version:
description: SOCKS host version used by proxy
choices:
- v4
- v5
default: v5
disabled:
type: identifier
when: 'HTTPS'
This can be done by defining a `my_identifier` variable.
This jinja variable comes from the `params` parameter of the `hidden` property.
.. code-block:: yaml
params:
my_identifier:
type: identifier
Here the `hidden` property's value is defined by a jinja calculation.
In this jinja calculation we have a `my_identifier` jinja variable.
.. code-block:: yaml
hidden:
jinja: |
{% if my_identifier == 'HTTPS' and manual.use_for_https %}
HTTPS is same has HTTP
{% endif %}
params:
my_identifier:
type: identifier
description: |
in HTTPS case if "manual.use_for_https" is set to True
.. type-along:: The `when` and `when_not` parameter notation
.. todo:: ça devrait être sur une autre page. déplacer cela ailleurs
Handling the SOCKS version
----------------------------
Now we need to handle the SOCKS version as show in the firefox configuration screenshot:
.. image:: images/firefox_soks_version.png
We'll just add a choice variable with a default value and a disabled property:
.. code-block:: yaml
version:
description: SOCKS host version used by proxy
choices:
- v4
- v5
default: v5
disabled:
type: identifier
when: 'HTTPS'
There is still something new about this YAML, though. It is the `when` parameter
of the `disabled` property. You have two possible notations: `when` or `when_not`.
These two notations are just a short hand of what we could express in jinja as
this code:
.. code-block:: jinja
{% if identifier == 'HTTPS' %}
when the identifer equals 'HTTPS' then the SOCKS version is disabled
{% endif %}
And the `when_not` parameter is just the logical opposite.
Here is the final version of our YAML dynamic family:
.. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/tag/v1.1_050/firefox/20-manual.yml
:language: yaml
:caption: firefox/20-proxy.yml
.. keypoints:: Key points
**keywords**
- calculation with a jinja type calculation
- calculation with a `when` or `when_not` parameter
- defining a jinja internal variable in a jinja calculation
**progress**
Here we have come to the possibility of making any kind of calculations based on the state of the :term:`configuration`.
This is an important feature to manage the stateful aspect of a configuration.