Quick reference

Quick reference examples for common OneFuse templating patterns

7 minute read

`_all_properties`

This is a Custom filter created for OneFuse to output all the Properties from the Deployment at Run Time.

The primary use-case for this is to access all the Properties when using the Scripting Module to utilize meta data within the OS scripts or to populate Ansible Host Variables which can be used for playbook executions.

Output rendered templateProperties with: _all_properties during Policy execution calls and/or Templating API.

Example

{#
  Example templateProperties stack:

  {
    "foo": "hello",
    "bar": "world"
  }
#}

{# Example 1 #}

{{ _all_properties }}


{# Example 2 #}

{% for key, value in _all_properties.items() %}
  Key: {{key}}
  Value: {{value}}
{% endfor %}


{# Example 3#}

{%for key in _all_properties %}
  {{key}}
{%endfor%}

{# Example 4 #}

{{ _all_properties.foo }}

Will not account for variables set after invocation, for example setting new variables using {%set foo = "bar" %}.

Result

{# Example 1 #}
=> {'foo': 'hello', 'bar': 'world'}


{# Example 2 #}
=> Key: foo
   Value: hello

   Key: bar
   Value: world


{# Example 3 #}
=> foo

   bar


{# Example 4 #}
=> hello

Sample use cases

Scripting use case

A sample use case would be to output the templateProperties into a file during the Scripting Policy execution for troubleshooting purposes.

#!/bin/bash
echo "template_properties = {% for key, value in _all_properties.items() %}{{key}}  =  {{value}}{% endfor %}" > /root/properties.txt

Example properties.txt file:

nameEnv  =  p
folderEnv  =  PROD
ipamEnv  =  prod
ouEnv  =  PRD
sgEnv  =  prod
dnsPolicy  =  prod
adPolicy  =  prod
location  =  atl
dnsSuffix  =  company.com
deployNameEnv  =  Prod
s3NameEnv  =  production

Ansible Tower use case

Configure the Extra Vars on the Ansible Tower Policy in OneFuse using the {{ _all_properties }} filter.

(opens full-size image in a new tab)

The properties will be added to Ansible Playbooks as variables for execution.

Getting a substring

Use the template below to create a substring, essentially a string that exists within another string. It is often referred to as “slicing”.

{# Template #}
string[start:end:step]

{# Get all characters from index start to end-1 #}
string[start:end]

{# Get all characters from index start to the end of the string #}
string[start:]

{# Get all characters from the beginning of the string to end-1 #}
string[:end]

{# Get all characters from start to end-1 discounting every step character #}
string[start:end:step]

start is the first index number where the slice starts (inclusive)
end is the second index number where the slice ends (exclusive)
step is every ‘step’ character after the current character to be included. The default value is 1.

If the variable name does not exist in a Property Set and you are attempting a Template Preview the variable with substring/slice, the render will fail.

Get the first 5 characters of a string

{% set foo = "Hello World" %}
{{ foo[0:5] }}

=> Hello

Get the last character of the string

{% set foo = "Hello World" %}
{{ foo[-1] }}

=> d

Get all the characters except the last 4 character and the 1st character

{% set foo = "Hello World" %}
{{ foo[1:-4] }}

=> ello W

Get every other character

{% set foo = "Hello World" %}
{{ foo[::2] }}

=> HloWrd

Import custom filters

Add custom filters

Log in to the target OneFuse appliance using a SCP utility (such as WinSCP, FileZilla, Cyberduck, etc).
Create a new .py file named jinja2_custom_filters.py in the directory: /var/opt/proserve
- Example /var/opt/proserve/jinja2_custom_filters.py
  
  The filename has to be jinja2_custom_filters.py with the Class: Jinja2CustomFilters

Modify the starter file below to create your custom filter(s).

# Filename: jinja2_custom_filters.py

# This example adds a new custom filter called "test_customer_filter"
# The "test_customer_filter" prefixes a variable with "Test-"
# If the variable is undefined/null, the variable returns as "Test"

from jinja2 import evalcontextfilter
from jinja2.exceptions import FilterArgumentError
from jinja2 import Undefined
import random
from utilities.logger import ThreadLogger
import json


logger = ThreadLogger(__name__)


class Jinja2CustomFilters:

    def register(self, environment):
        logger.info("Registering Customer Custom Filters")
        environment.filters["test_customer_filter"] = self.test_customer_filter

    @evalcontextfilter
    def test_customer_filter(self, context, value):
        if isinstance(value, Undefined) or not value or value is None:
            return f"Test"
        return f"Test-{value}"

Restart the OneFuse appliance:
1. SSH to the target OneFuse appliance:
  - ssh as the root user and switch to root user with sudo su - and then run required commands.
2. Run command:
```
service httpd restart
```

Use and test the new filter via UI or API:

{# Example uses "test_customer_filter" #}

{{ "ABC" | test_customer_filter }}

=> Test-ABC

Add additional custom filters

Additional filters are added to jinja2_custom_filters.py. See the sample file below:

# Filename: jinja2_custom_filters.py

# This example adds a new custom filter called "test_customer_filter"
# The "test_customer_filter" prefixes a variable with "Test-"
# If the variable is undefined/null, the variable returns as "Test"

from jinja2 import evalcontextfilter
from jinja2.exceptions import FilterArgumentError
from jinja2 import Undefined
import random
from utilities.logger import ThreadLogger
import json


logger = ThreadLogger(__name__)


class Jinja2CustomFilters:

    def register(self, environment):
        logger.info("Registering Customer Custom Filters")
        environment.filters["test_customer_filter"] = self.test_customer_filter

        #New Filter
        environment.filters["test_customer_filter2"] = self.test_customer_filter2

    @evalcontextfilter
    def test_customer_filter(self, context, value):
        if isinstance(value, Undefined) or not value or value is None:
            return f"Test"
        return f"Test-{value}"

    #New Filter
    @evalcontextfilter
    def test_customer_filter2(self, context, value):
        if isinstance(value, Undefined) or not value or value is None:
            return f"Test2"
        return f"Test2-{value}"

Remember to restart the OneFuse appliance.

Add Jinja2 extensions

Find a jinja2 extension from pypi.org.
Follow pip install instructions from the extension on the OneFuse appliance.
Call the extension into the jinja2_custom_filters.py file.

See the sample file below that uses the jinja2-time extension as an example:

# Filename: jinja2_custom_filters.py

# This example calls the jinja2-time extension

from jinja2 import evalcontextfilter
from jinja2.exceptions import FilterArgumentError
from jinja2 import Undefined
import random
from utilities.logger import ThreadLogger
import json


logger = ThreadLogger(__name__)


class Jinja2CustomFilters:

    def register(self, environment):
        logger.info("Registering Customer Custom Filters")
        environment.filters["test_customer_filter"] = self.test_customer_filter
        # New Extension - Jinja2 Time
        environment.add_extension('jinja2_time.TimeExtension')

    @evalcontextfilter
    def test_customer_filter(self, context, value):
        if isinstance(value, Undefined) or not value or value is None:
            return f"Test"
        return f"Test-{value}"

Remember to restart the OneFuse appliance to use the new filters.

{# Example from jinja2-time #}
{% now 'local' %}

Template Tester

Template Tester API: OneFuse Templating

User needs to have one of the following Workspace Roles to use Template Tester: Admin, Member, or Viewer.

Access Template Tester via OneFuse UI

Log in to the OneFuse UI
Select Templating > Template Tester from the left navigation menu

Template Tester: Template tab

The Template tab allows Template Previews for the Template defined using the Active Property Set. This assumes at least one Property Set exists on this OneFuse Instance.

Provide a template in the Template field.
Select the eye icon button on the Template field to view the rendered result with the Active Property Set.

Example Template:

{{ OS | first | lower }}{{ Environment | first | lower }}{{ Application | first | lower }}

Example Template Render:

{# Active Property Set: prod #}
{#
  {
    "Environment": "production",
    "OS": "Linux",
    "Application": "Web Servers"
  }
#}

=> lew

Template Tester: Override tab

The Override tab allows you to provide custom properties that will render for the Template provided in the Template tab.

Provide a template in the Template field.
Provide custom properties in JSON format in the Custom Properties field.
Select the eye icon button on the Custom Properties field to view the rendered result.

Example Template:

{{ OS | first | lower }}{{ Environment | first | lower }}{{ Application | first | lower }}

Example Template Render:

{# Custom Properties #}
{#
  {
    "Environment": "dev",
    "OS": "Windows",
    "Application": "Database"
  }
#}

=> dwd

Get undeclared template variables

Get a return array of all templated variables that were not renderable (for example, a property did not have a value) within the Template.

Refer to the following OneFuse API: Templating: templateVariables POST

{# Example POST BODY #}
{
 "template": "template {{ Environment }} {{ Application.nameApp }}"
}

{# Example POST RESPONSE #}
[
    "Environment",
    "Application.nameApp"
]