Jinja Syntax and Examples for Configuration Templates - TechLibrary (2023)

CSO configuration templates consist of three components:

• A Jinja template configuration, which contains the logicand the configuration for the configuration template. (Jinja is atemplate engine for Python and you can find several Jinja resourceson the Web.)

• A Yang data model file, which contains the descriptorsfor the configuration schema.

• A ViewDef (view definition) file, which is a JavaScriptObject Notation (JSON) file that is used to specify the GUI aspectsof the configuration template.

When you use the Add Configuration Template workflow to adda template, you specify the template configuration and logic by usingthe Jinja template language. CSO then generates the Yang data modeland the ViewDef files automatically based on template configurationand logic that you specified. The generation of the Yang and ViewDeffiles is transparent to the user and doesn’t require any userintervention.

Jinja Syntax and CSO Keywords

The tables below list the Jinja syntax used commonly in configurationtemplates and the keywords used in configuration templates respectively.

{{tenant_name}}

{# This is an example of comment in Jinja syntax #}

{% for prefix in Trusted_Network_Prefix_List %}set groups trusted‐prefix policy‐options prefix‐list re‐ssh {{prefix.Trusted_Network_Prefix_List}}{% endfor %}

Example 1: Convert a Single Junos OS Command to Jinja Syntax

If you want to convert a single Junos OS command into Jinjasyntax for use in a configuration template:

1. Identify the variables that are configured in the JunosOS command.

   For example, in the command set snmp trap-group CSO-Trp-Grptargets 192.0.2.100, the variables configured are CSO-Trp-Grpand 192.0.2.100.

2. Convert the Junos OS CLI command to Jinja syntax by enclosingeach variable in double curly braces as follows: {{ Variable_Name }}.

   So, in this example, if we use Trap_Group_Name and SNMP_Host_IP_Address as the variable names,the Jinja syntax for the command is as follows:
3. If you paste this in the Template Configuration sectionof the Add Configuration Template workflow, CSO detects the parametersas follows:

   Parameters
4. If you use the preview feature to render the configuration(for an OpCo named Juniper and a configuration template named Test),using the values indicated in the first step, CSO renders the configurationas follows:
   (Video) Salt Formulas Working Group 2021-FEB-09

   Notice that although you provided the JInja syntax for a singleJunos OS command, CSO added additional commands to the configuration.This is because, by default, CSO uses Junos OS groups to generatethe configuration. Junos OS groups make it easier to apply and deleteconfigurations. For more information, see Understanding Junos OS Configuration Groups.

   If you don’t want to use Junos OS groups, you must turnon the advanced mode in the configuration template, when you specifythe configuration in Jinja syntax..

Example 2: Convert a Junos OS Configuration Snippet to JinjaSyntax

In this example, we’ll convert the following Junos OSconfiguration snippet into Jinja syntax for use in a configurationtemplate:

To convert the Junos OS configuration into Jinja syntax:

1. Identify the variables that are configured in the JunosOS commands. For ease of understanding, the variables are enclosedwithin angular brackets (<>) in the example below.Note

   In this example, we’re not considering DHCP-SERVER asa variable.

   set forwarding-options dhcp-relay server-group DHCP-SERVER<Relay_IP>

   set forwarding-options dhcp-relay active-server-group DHCP-SERVER

   set forwarding-options dhcp-relay group <Relay_Group_Name> interface <Relay_Interface>

   set security zones security-zone <Relay_Zone> host-inbound-traffic system-services dhcp

2. Convert each Junos OS CLI command to Jinja syntax by identifyingthe variables, providing a name for each variable, and enclosing eachvariable in double curly braces. So, in this case, the Jinja syntaxis as follows:
3. When you paste this in the Template Configuration sectionof the Add Configuration Template workflow, CSO detects the parametersas follows:

   Parameters
4. If you use the preview feature to render the configuration(for an OpCo named Juniper and a configuration template named Test),using the values for this example, CSO renders the configuration asfollows:

Example 3: Use Conditional Logic

In this example, which is a modified version of the precedingexample, we’ll see how you can use conditional logic (if and for statements) ina configuration template.

The explanation of the example above is as follows:

1. In this example, we add an if statement and enclose the configuration within that statement asfollows:

   This means that the configuration is applied only if the enable_Forwarding_Optionsis True. If enable_Forwarding_Options is False, then no configurationis applied.

   Tip

   If you want to apply a different configuration when enable_Forwarding_Optionsis False, you can use the else statement.

2. Then, we add a for statementto enable the configuration of more than one set of values for the Relay_Group_Name, Relay_Interface, and Relay_Zone variables.

   When you use a for statement, theGUI rendered by CSO (when you use the preview feature) displays thevariables in table (grid). You can then use the Add icon (+) to add rows to the table and configure one or more sets of valuesas needed.

3. When you paste the Jinja commands in the Template Configurationsection of the Add Configuration Template workflow, CSO detects theparameters as follows:

   Parameters
4. If you use the preview feature to render the configuration(for an OpCo named Juniper and a configuration template named Test),and provide values for the parameters, including two sets of valuesfor Relay_Group_Name, Relay_Interface, and Relay_Zone, CSO renders the configurationas follows:

Example 4: Use Variable Substitution

In this example, we use a variable as part of the configurationcommand such that the value that we specify forthe variable is used in the command.

The explanation of the example above is as follows:

1. We use the VLAN_Id attributeof the pool parameter to set the JunosOS configuration parameters vlans and vlan-id.
2. When you paste the Jinja command set groupsMIST vlans V-{{pool.VLAN_Id}} vlan-id {{pool.VLAN_Id}} in the Template Configuration section of the Add Configuration Templateworkflow, CSO detects the parameters as follows:

   Parameters

   This is because we’ve used the dot (.) operator to referencethe attribute VLAN_Id of the parameter pool.

3. If you use the preview feature to render the configuration(for an OpCo named Juniper and a configuration template named Test),and provide the value 120 for VLAN_Id,CSO renders the configuration as follows:

   In the rendered configuration command, you can see that theparameters vlans and vlan-id are set to V-120 and 120 respectively, based on the value thatwe provided for the VLAN_Id parameter.

Example 5: Use Filters, Concatenation, and Set Variables

In this example, we’ll look at how to set a variable usingconcatenation and filters, and then use that variable in a Junos OSconfiguration command.

The explanation of the example above is as follows:

1. The Jinja statement {% set pool_name = Dhcp_Server_Name+ ’_’ + Interface | replace(“/”,”_”)%} is used to set a variable called pool_name, using two other variables Dhcp_Server_Name and Interface, as follows:
   1. The | (pipe) operator is usedto separate variables from filters, which are functions that modifyvariables. In this example, we use the replace(“/”,”_”) filter to modify the Interface variable byreplacing the / (forward slash) characters with _ (underscore) characters.
   2. Then, we use the + operatorto concatenate the resulting string with the variable Dhcp_Server_Name.Note

      The operator + is typically usedto add numbers, but when the values are strings, the strings are concatenated.

   3. Finally, the tag set is used(along with the = operator) to set thevariable called pool_name to the concatenatedvariable.
2. Then, the Junos OS command set system servicesdhcp-local-server overrides process-inform pool {{pool_name}} is used to configure the Junos OS configuration statement pool using the variable pool_name that weset in the preceding step.
3. When you paste the Jinja commands in the Template Configurationsection of the Add Configuration Template workflow, CSO detects theparameters as follows:

   Parameters

   As you can see, the Junos OS command or the pool_name variables are not displayed because we’re using the Interface and Dhcp_Server_Name variablesto arrive at the final Junos OS configuration.

4. If you use the preview feature to render the configuration(for an OpCo named Juniper and a configuration template named Test),and provide the values LA_dhcp_srvr for Dhcp_Server_Name and ge-0/1/2 for the Interface, CSO rendersthe configuration as follows:

   As explained in a previous step, the / characters in ge-0/1/2are first replaced with _ characters, which changes the string toge-0_1_2. This string is concatenated with LA_dhcp_srvr to producethe string LA_dhcp_srvr_ge-0_1_2, which is used in the Junos OS configurationcommand.

   Therefore, the Junos OS configuration command generated is set system services dhcp-local-server overrides process-inform poolLA_dhcp_srvr_ge-0_1_2.

Example 6: Test a Value

In this example, we’ll look at how to test a value andperform actions based on the result of the test conditions.

The explanation of the example above is as follows:

1. We test the parameter NewNetwork.VLAN_Id for two conditions:

   1. Whether the parameter is defined (by using the NewNetwork.VLAN_Id is defined condition)

   2. Whether the length of the parameter is greater than two(by using the condition (NewNetwork.VLAN_Id | count)> 2)

   Because we use the keyword and:

   • The configuration command set vlan-id {{NewNetwork.VLAN_Id}} is added to the configuration (that CSO generates) when both conditions hold true.

   • The configuration set vlans VL-{{NewNetwork.VLAN_Id}} is added to the configuration when either of the conditions is false.

2. When you paste the Jinja commands in the Template Configurationsection of the Add Configuration Template workflow, CSO detects theparameters as follows:

   Parameters
3. If you use the preview feature to render the configuration(for an OpCo named Juniper and a configuration template named Test),and:

   • Provide the value 125 for VLAN_Id, CSO renders the configuration as follows becauseboth conditions are true:

   • Provide the value 65 for VLAN_Id, CSO renders the configuration as follows becauseone of the conditions is false (length of the parameter is not greaterthan 2):