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Table of Contents Expand all

play_arrow Overview
- play_arrow Junos Automation Scripts Overview
- play_arrow Junos XML Management Protocol and Junos XML API Overview
play_arrow Automation Scripting Using XSLT
- play_arrow XSLT Overview
- play_arrow Standard XPath and XSLT Functions Used in Automation Scripts
- play_arrow Standard XSLT Elements and Attributes Used in Automation Scripts
play_arrow Automation Scripting Using SLAX
- play_arrow SLAX Overview
- play_arrow SLAX Statements
- play_arrow The libslax Distribution for Automation Scripting
play_arrow Automation Scripting Using Python
- play_arrow Python Overview
play_arrow Automation Script Input
- play_arrow Global Parameters in Automation Scripts
  - Global Parameters and Variables in Junos OS Automation Scripts
play_arrow Extension Functions and Named Templates for Automation Scripts
play_arrow Manage Automation Scripts
- play_arrow Store and Enable Scripts
- play_arrow Configure a Remote Source for Scripts
- play_arrow Configure the Session Protocol for Scripts
  - Understanding the Session Protocol in Automation Scripts
  - Example: Specify the Session Protocol for a Connection within Scripts
- play_arrow Control Execution of Scripts
- play_arrow Synchronize Scripts Between Routing Engines
- play_arrow Convert Scripts Between SLAX and XSLT
  - Convert Scripts Between SLAX and XSLT
play_arrow Commit Scripts
- play_arrow Commit Scripts Overview
  - Commit Script Overview
  - How Commit Scripts Work
- play_arrow Create and Execute Commit Scripts
- play_arrow Generate a Custom Warning, Error, or System Log Message Using Commit Scripts
- play_arrow Generate Persistent or Transient Configuration Changes Using Commit Scripts
- play_arrow Create Custom Configuration Syntax with Commit Script Macros
- play_arrow Commit Script Examples
- play_arrow Junos XML and XSLT Tag Elements Used in Commit Scripts
- play_arrow Troubleshoot Commit Scripts
play_arrow Op Scripts
- play_arrow Op Scripts Overview
  - Op Script Overview
  - How Op Scripts Work
- play_arrow Create and Execute Op Scripts
- play_arrow Op Script Examples
- play_arrow Provision Services Using Service Template Automation
  - Service Template Automation Overview
  - Example: Configure Service Template Automation
- play_arrow Troubleshoot Op Scripts
  - Trace Op Script Processing on Devices Running Junos OS
  - Trace Script Processing on Devices Running Junos OS Evolved
play_arrow Event Policies and Event Scripts
play_arrow SNMP Scripts
- play_arrow SNMP Scripts Overview
  - SNMP Scripts Overview
- play_arrow Create and Execute SNMP Scripts
- play_arrow SNMP Script Example
  - Example: Process Unsupported OIDs with an SNMP Script
- play_arrow Troubleshoot SNMP Scripts
  - Trace SNMP Script Processing on Devices Running Junos OS
  - Trace Script Processing on Devices Running Junos OS Evolved
play_arrow Configuration Statements and Operational Commands
- Junos CLI Reference Overview

list Table of Contents

English

Example: Prepend a Global Policy

date_range 31-Jan-22

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This commit script example ensures that a BGP global import policy is applied to all your BGP imports before any other import policies are applied.

Requirements

This example uses a device running Junos OS.

Overview and Commit Script

For most configuration objects, the order in which the object or its children is created is not significant, because the Junos OS configuration management software stores and displays configuration objects in predetermined positions in the configuration hierarchy. However, some configuration objects—such as routing policies and firewall filters—consist of elements that must be processed and analyzed sequentially in order to produce the intended routing behavior.

This example commit script ensures that a BGP global import policy is applied to all your BGP imports before any other import policies are applied.

This example automatically prepends the bgp_global_import policy in front of any other BGP import policies. If the bgp_global_import policy statement is not included in the configuration, an error message is generated, and the commit operation fails.

Otherwise, the commit script uses the insert="before" Junos XML protocol attribute and the position() XSLT function to control the position of the global BGP policy in relation to any other applied policies. The insert="before" attribute inserts the bgp_global_import policy in front of the first preexisting BGP import policy.

If there is no preexisting default BGP import policy, the global policy is included in the configuration.

The example script is shown in both XSLT and SLAX syntax:

XSLT Syntax

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<?xml version="1.0" standalone="yes"?>
<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:junos="http://xml.juniper.net/junos/*/junos"
    xmlns:xnm="http://xml.juniper.net/xnm/1.1/xnm"
    xmlns:jcs="http://xml.juniper.net/junos/commit-scripts/1.0">
    <xsl:import href="../import/junos.xsl"/>
 
    <xsl:template match="configuration">
        <xsl:if  test="not(policy-options/policy-statement[name='bgp_global_import'])">
            <xnm:error>
                <message>Policy error: Policy bgp_global_import required</message>
            </xnm:error>
        </xsl:if>
        <xsl:for-each select="protocols/bgp | protocols/bgp/group | 
                                              protocols/bgp/group/neighbor">
            <xsl:variable name="first" select="import[position() = 1]"/>
            <xsl:if test="$first">
                <xsl:call-template name="jcs:emit-change">
                    <xsl:with-param name="tag" select="'transient-change'"/>
                    <xsl:with-param name="content">
                        <import insert="before"
                                     name="{$first}">bgp_global_import</import>
                    </xsl:with-param>
                </xsl:call-template>
            </xsl:if>
        </xsl:for-each>
        <xsl:for-each select="protocols/bgp">
            <xsl:if test="not(import)">
                <xsl:call-template name="jcs:emit-change">
                    <xsl:with-param name="tag" select="'transient-change'"/>
                    <xsl:with-param name="content">
                        <import>bgp_global_import</import>
                    </xsl:with-param>
                </xsl:call-template>
            </xsl:if>
        </xsl:for-each>
    </xsl:template>
</xsl:stylesheet>

SLAX Syntax

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version 1.0;
ns junos = "http://xml.juniper.net/junos/*/junos";
ns xnm = "http://xml.juniper.net/xnm/1.1/xnm";
ns jcs = "http://xml.juniper.net/junos/commit-scripts/1.0";
import "../import/junos.xsl";
 
match configuration {
    if (not(policy-options/policy-statement[name='bgp_global_import'])) {
        <xnm:error> {
            <message> "Policy error: Policy bgp_global_import required";
        }
    }
    for-each (protocols/bgp | protocols/bgp/group | 
                     protocols/bgp/group/neighbor) {
        var $first = import[position() = 1];
        if ($first) {
            call jcs:emit-change($tag = 'transient-change') {
                with $content = {
                    <import insert="before" name="{$first}"> "bgp_global_import";
                }
            }
        }
    }
    for-each (protocols/bgp) {
        if (not(import)) {
            call jcs:emit-change($tag = 'transient-change') {
                with $content = {
                    <import> "bgp_global_import";
                }
            }
        }
    }
}

Configuration

Procedure

Step-by-Step Procedure

To download, enable, and test the script:

Copy the script into a text file, name the file bgp-global-import.xsl or bgp-global-import.slax as appropriate, and copy it to the /var/db/scripts/commit/ directory on the device.

Select the following test configuration stanzas, and press Ctrl+c to copy them to the clipboard.

If you are using the SLAX version of the script, change the filename at the [edit system scripts commit file] hierarchy level to bgp-global-import.slax.

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system {
    scripts {
        commit {
            allow-transients;
            file bgp-global-import.xsl;
        }
    }
}
interfaces {
    fe-0/0/0 {
        unit 0 {
            family inet {
                address 192.168.16.2/24;
            }
            family inet6 {
                address 2002:18a5:e996:beef::2/64;
            }
        }
    }
}
routing-options {
    autonomous-system 64500;
}
protocols {
    bgp {
        group fish {
            neighbor 192.168.16.4 {
                import [ blue green ];
                peer-as 64501;
            }
            neighbor 192.168.16.6 {
                peer-as 64502;
            }
        }
    }
}
policy-options {
    policy-statement blue {
        from protocol bgp;
        then accept;
    }
    policy-statement green {
        then accept;
    }
    policy-statement bgp_global_import {
        then accept;
    }
}

In configuration mode, issue the load merge terminal command to merge the stanzas into your device configuration.
```
[edit]
user@host# load merge terminal
[Type ^D at a new line to end input]
... Paste the contents of the clipboard here ...
```
1. At the prompt, paste the contents of the clipboard by using the mouse and the paste icon.
2. Press Enter.
3. Press Ctrl+d.
Commit the configuration.
```
user@host# commit
```

Verification

Purpose

Verify that the script behaves as expected.

Action

When you issue the show protocols configuration mode command, the bgp_global_import import policy is not displayed, because it is added as a transient change.

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[edit]
user@host# show protocols
bgp {
    group fish {
        neighbor 192.168.16.4 {
            import [ blue green ];
            peer-as 64501;
        }
        neighbor 192.168.16.6 {
            peer-as 64502;
        }
    }
}

The commit script adds the import bgp_global_import statement at the [edit protocols bgp] hierarchy level and prepends the bgp_global_import policy to the 192.168.16.4 neighbor policy chain. Issue the show protocols | display commit-scripts to view all configuration statements including transient changes.

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[edit]
user@host# show protocols | display commit-scripts
bgp {
    import bgp_global_import;
    group fish {
        neighbor 192.168.16.4 {
            import [ bgp_global_import blue green ];
            peer-as 64501;
        }
        neighbor 192.168.16.6 {
            peer-as 64502;
        }
    }
}

After you add a policy to the 192.168.16.6 neighbor, which previously had no policies applied, the bgp_global_import policy is prepended. Issue the show protocols | display commit-scripts command to view all configuration statements including transient changes.

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[edit]
user@host# set protocols bgp group fish neighbor 192.168.16.6 import green

[edit]
user@host# show protocols | display commit-scripts
bgp {
    import bgp_global_import;
    group fish {
        neighbor 192.168.16.4 {
            import [ bgp_global_import blue green ];
            peer-as 64501;
        }
        neighbor 192.168.16.6 {
            import [ bgp_global_import green ];
            peer-as 64502;
        }
    }
}

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