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Using Ansible to Retrieve or Compare Junos OS Configurations

SUMMARY Use the Juniper Networks Ansible modules to retrieve or compare configurations on devices running Junos OS.

Juniper Networks provides Ansible modules that enable you to manage the configuration on devices running Junos OS. Table 1 outlines the available modules, which enable you to retrieve or compare Junos OS configurations.

Table 1: Modules to Retrieve or Compare Configurations

Content Set

Module Name

juniper.device collection

config

Juniper.junos role

juniper_junos_config

Note:

Starting in Juniper.junos Release 2.0.0, the juniper_junos_config module combines and replaces the functionality of the junos_commit, junos_get_config, junos_install_config, and junos_rollback modules.

You can use the modules to request the complete configuration or selected portions of the configuration for both the native Junos OS configuration as well as for configuration data corresponding to third-party YANG data models that have been added to the device. To retrieve the configuration from a device running Junos OS, execute the config or juniper_junos_config module with the retrieve parameter. The module’s response includes the configuration in text format in the config and config_lines keys, unless the return_output option is set to false. You can also compare the active configuration with a previously committed configuration.

The following sections discuss how to use the modules to retrieve or compare Junos OS configurations.

How to Specify the Source Database for the Configuration Data

When you use the config or juniper_junos_config module to retrieve the configuration, you must include the retrieve parameter in the module’s argument list and specify the configuration database from which to retrieve the data. You can retrieve data from the committed configuration database or from the candidate configuration database by setting retrieve to 'committed' or 'candidate', respectively.

Committed Configuration Database

The following playbook retrieves the complete committed configuration in text format for each device in the inventory group:

Candidate Configuration Database

The following playbook retrieves the complete candidate configuration in text format for each device in the inventory group. The module returns an error if the database is locked or modified.

How to Specify the Scope of the Configuration Data to Return

In addition to retrieving the complete Junos OS configuration, you can use the config and juniper_junos_config modules to retrieve specific portions of the configuration by including the module’s filter parameter. The filter parameter’s value is a string containing the subtree filter that selects the configuration statements to return. The subtree filter returns the configuration data that matches the selection criteria. When multiple hierarchies are requested, the value of filter must represent all levels of the configuration hierarchy starting at the root (represented by the <configuration> element) down to each element to display.

The following playbook retrieves and prints the configuration at the [edit interfaces] and [edit protocols] hierarchy levels in the committed configuration database for each device:

The following playbook retrieves and prints the configuration for the ge-1/0/1 interface:

The following playbook retrieves and prints the configuration committed at the [edit system services] hierarchy level:

How to Specify the Format of the Configuration Data to Return

When you use the config or juniper_junos_config module to retrieve the configuration, the module invokes the Junos XML protocol <get-configuration> operation, which can return Junos OS configuration data as formatted text, Junos XML elements, Junos OS set commands, or JavaScript Object Notation (JSON). By default, the module returns configuration data as formatted text, which uses newlines, tabs and other white space, braces, and square brackets to indicate the hierarchical relationships between the statements.

To specify the format in which to return the configuration data, set the format parameter equal to the desired format. To explicitly request text format, or to request Junos XML elements, Junos OS set commands, or JSON format, set the format value to 'text', 'xml', 'set', or 'json', respectively. The config and config_lines keys contain the configuration in the requested format. If you request Junos XML or JSON format, the config_parsed key contains the equivalent configuration in JSON format.

The following playbook retrieves the complete committed configuration for each device in the inventory group in XML format:

How to Retrieve Configuration Data for Third-Party YANG Data Models

You can load standardized or custom YANG modules on devices running Junos OS to add data models that are not natively supported by Junos OS but can be supported by translation. You configure nonnative data models in the candidate configuration using the syntax defined for those models. When you commit the configuration, the data model’s translation scripts translate that data and commit the corresponding Junos OS configuration as a transient change in the checkout configuration.

The candidate and active configurations contain the configuration data for nonnative YANG data models in the syntax defined by those models. You can use the config or juniper_junos_config module to retrieve configuration data for standard (IETF, OpenConfig) and custom YANG data models in addition to retrieving the native Junos OS configuration by including the appropriate module arguments. By default, configuration data for third-party YANG data models is not included in the module’s reply.

To retrieve configuration data that is defined by a nonnative YANG data model in addition to retrieving the Junos OS configuration, execute the module with the model parameter, and include the namespace parameter when appropriate. The model argument takes one of the following values:

  • custom—Retrieve configuration data that is defined by custom YANG data models. You must include the namespace argument when retrieving data for custom YANG data models.

  • ietf—Retrieve configuration data that is defined by IETF YANG data models.

  • openconfig—Retrieve configuration data that is defined by OpenConfig YANG data models.

  • True—Retrieve all configuration data, including the complete Junos OS configuration and data from any YANG data models.

If you specify the ietf or openconfig value for the model argument, the module automatically uses the appropriate namespace. If you retrieve data for a custom YANG data model by using model: "custom", you must also include the namespace argument with the corresponding namespace.

If you include the model argument with the value custom, ietf, or openconfig and also include the filter argument to return a specific XML subtree, Junos OS only returns the matching hierarchy from the nonnative data model. If the Junos OS configuration contains a hierarchy of the same name, for example "interfaces", it is not included in the reply. The filter option is not supported when using model: "True".

When you use the config or juniper_junos_config module to retrieve nonnative configuration data, you can only specify the format of the returned data if you also include the filter parameter. If you omit the filter parameter, you must specify format: "xml".

The following playbook retrieves the OpenConfig interfaces configuration hierarchy from the committed configuration. If you omit the filter argument, the RPC returns the complete Junos OS and OpenConfig configurations.

The following task retrieves the l2vpn configuration hierarchy from the committed configuration for a custom YANG data model with the given namespace:

The following task retrieves the complete Junos OS committed configuration as well as the configuration data for other YANG data models that have been added to the device:

How to Specify Options That Do Not Have an Equivalent Module Argument

When you use the config or juniper_junos_config module to retrieve the configuration, the module invokes the Junos XML protocol <get-configuration> operation. The modules support explicit arguments for many of the <get-configuration> attributes, for example, the format attribute. The modules also support the options argument, which enables you to include any additional <get-configuration> attributes that do not have an equivalent module argument. The options argument takes a dictionary of key/value pairs of any attributes supported by the <get-configuration> operation.

For the complete list of attributes supported by the Junos XML protocol <get-configuration> operation, see https://www.juniper.net/documentation/en_US/junos/topics/reference/tag-summary/junos-xml-protocol-get-configuration.html.

For example, the modules retrieve data from the pre-inheritance configuration, in which the <groups>, <apply-groups>, <apply-groups-except>, and <interface-range> tags are separate elements in the configuration output. To retrieve data from the post-inheritance configuration, which displays statements that are inherited from user-defined groups and ranges as children of the inheriting statements, you can include the options argument with inherit: "inherit".

The following playbook retrieves the configuration data at the [edit system services] hierarchy level from the post-inheritance committed configuration. In this case, if the configuration also contains statements configured at the [edit groups global system services] hierarchy level, those statements would be inherited under [edit system services] in the post-inheritance configuration and returned in the retrieved configuration data.

How to Save Configuration Data To a File

When you use the config or juniper_junos_config module to retrieve the configuration, you can save the returned configuration data in a file on the local Ansible control node by including the module’s dest_dir or dest parameter. The dest_dir option just specifies a directory, and the dest option can specify both a path and a filename. If an output file already exists with the target name, the module overwrites the file.

To specify the directory on the local Ansible control node where the retrieved configurations are saved, include the dest_dir argument, and define the path to the target directory. The configuration for each device is stored in a separate file named hostname.config.

The following playbook retrieves the committed configuration from all devices in the inventory group and saves each device configuration to a separate file in the configs directory under the playbook directory on the Ansible control node:

To specify the path and filename for the output files, include the dest argument, and define the absolute or relative path of the file. If you include the dest argument, but omit the directory, the files are saved in the playbook directory. If you retrieve the configuration for multiple devices, the dest argument must include a variable such as {{ inventory_hostname }} to differentiate the filename for each device. If you do not differentiate the filenames, the configuration file for each device will overwrite the configuration file of the other devices.

The following playbook retrieves the [edit system services] hierarchy from the committed configuration database on all devices in the inventory group and saves each device configuration to a separate file in the playbook directory on the Ansible control node. Each file is uniquely identified by the device hostname.

If you are saving the configuration data to files and do not want to duplicate the configuration data in the module’s response, you can you can optionally include return_output: false in the module’s argument list. Setting return_output to false causes the module to omit the config, config_lines, and config_parsed keys in its response. Doing this might be necessary if the devices return a significant amount of configuration data.

How to Compare the Active Configuration to a Previous Configuration

The config and juniper_junos_config modules enable you to compare the active configuration to a previously committed configuration, or rollback configuration. To compare the active configuration to a previous configuration, include the following module arguments:

By default, when you include the rollback: id argument, the module rolls back the configuration, performs a commit check, and commits the changes. You must include the commit: false argument to only compare the configurations and prevent the module from loading and committing the rollback configuration. Including the check: false argument prevents the unnecessary commit check operation.

The modules return the diff and diff_lines keys, which contain the configuration differences between the active and previous configuration in diff or patch format.

  • diff— dictionary that contains a single key named prepared and its value, which is a single multi-line string containing the differences.

    Note:

    Starting inJuniper.junos Release 2.2.0, the diff key returns a dictionary instead of a string.

  • diff_lines—list of single line strings containing the differences..

To save the differences to a file on the local Ansible control node, include the diffs_file argument, and define the absolute or relative path of the output file. If you include the diffs_file argument but omit the directory, the files are saved in the playbook directory. If you compare the configurations on multiple devices, the diffs_file argument must include a variable such as {{ inventory_hostname }} to differentiate the filename for each device. If you do not differentiate the filenames, the output file for each device will overwrite the output file of the other devices.

The following playbook prompts for the rollback ID of a previously committed configuration, compares the committed configuration to the specified rollback configuration, saves the comparison to a uniquely-named file, and also prints the response to standard output:

Release History Table
Release
Description
2.2.0
Starting inJuniper.junos Release 2.2.0, the diff key returns a dictionary instead of a string.
2.0.0
Starting in Juniper.junos Release 2.0.0, the juniper_junos_config module combines and replaces the functionality of the junos_commit, junos_get_config, junos_install_config, and junos_rollback modules.