Connect to Junos Devices Using Ansible

The Juniper Networks Ansible modules do not require Python on Junos devices because they use Junos PyEZ and the Junos XML API over NETCONF to interface with the device. Therefore, to perform operations on Junos devices, you must run modules locally on the Ansible control node, where Python is installed. You can run the modules locally by including connection: local in the playbook play. When you use connection: local, Ansible establishes a separate connection to the host for each task in the play that performs operations on the host.

The juniper.device collection modules also support connection: juniper.device.pyez for establishing a persistent connection to a host. When you use a persistent connection, Ansible still executes the modules locally on the control node, but it only establishes and maintains a single connection to each host, which persists over the execution of all tasks in the play. Establishing a persistent connection to a host can be more efficient for executing multiple tasks than establishing a separate connection to the host for every task in the play.

Table 2 summarizes the Ansible connections and the content sets that support them.

Table 2: Ansible Connections Supported By Juniper Networks Modules

Ansible connection	Description	Content Set Support
connection: local	Execute the modules locally on the Ansible control node but establish a separate connection to a host for each task in the play that performs operations on the host.	juniper.device collection Juniper.junos role (deprecated)
connection: juniper.device.pyez	Execute the modules locally on the Ansible control node but establish a persistent connection to a host that persists over the execution of all tasks in the play.	juniper.device collection

When you use connection: local, Ansible establishes a separate connection to a host for each module, which means you can define module-specific connection and authentication parameters in the module’s argument list. By contrast, when you use connection: juniper.device.pyez, the connection persists across all tasks in the play, and thus you must define the connection and authentication parameters globally for all modules. You can define the parameters in the vars: section of a play, in addition to providing them through other means, for example, in an SSH configuration file or in the Ansible inventory file. For additional details, see Authenticate Users Executing Ansible Modules on Junos Devices.

The following playbook establishes a persistent connection to each host that is used for all tasks in the play. The user’s credentials, which are stored in an Ansible vault file, are defined in the play’s vars: section.

The Juniper Networks Ansible modules support using SSH to connect to a Junos device. You can establish a NETCONF session over SSH on the device’s management interface or you can establish an SSH connection with a console server that is directly connected to the device’s CONSOLE port. The SSH server must be able to authenticate the user using standard SSH authentication mechanisms, as described in Authenticate Users Executing Ansible Modules on Junos Devices. To establish a NETCONF session over SSH, you must also satisfy the requirements outlined in Set up Ansible for Junos OS Managed Nodes.

The Juniper Networks modules automatically query the default SSH configuration file at ~/.ssh/config, if one exists. You can also include the ssh_config parameter to specify a different configuration file.

When using SSH to connect to a Junos device or to a console server connected to the device, the modules first attempt SSH public key-based authentication and then try password-based authentication. When password-based authentication is used, the supplied password is used as the device password. When SSH keys are in use, the supplied password is used as the passphrase for unlocking the private key. If the SSH private key has an empty passphrase, then a password is not required. However, we do not recommend using SSH private keys with empty passphrases.

The following playbook establishes a NETCONF session over SSH with a Junos device and retrieves the device facts. The playbook uses SSH keys in the default location.

The Juniper Networks Ansible modules also enable you to connect to a Junos device through an SSH connection to a console server. In this case, you must specify the login credentials for both the Junos device and the console server. You use the user and passwd parameters to specify the Junos OS login credentials, and you use the cs_user and cs_passwd parameters to specify the console server credentials. When SSH keys are in use, cs_passwd is the passphrase for the private key.

The following playbook prompts for the user’s credentials for the console server and the Junos device. The module authenticates with the console server and then the Junos device. If authentication is successful, the playbook then retrieves the device facts from the managed node and prints the Junos OS version.

The Juniper Networks modules automatically query the default SSH client configuration file at ~/.ssh/config, if it exists. You can use a different SSH configuration file by including the ssh_config parameter and specifying the location of the configuration file. For example:

The Juniper Networks modules enable you to connect to a Junos device using telnet, which provides unencrypted access to the network device. You can telnet to the device’s management interface or to a console server that is directly connected to the device’s CONSOLE port. Accessing the device through a console server enables you to initially configure a new or zeroized device that is not yet configured for remote access. To telnet to the management interface, you must configure the Telnet service at the [edit system services] hierarchy level on all devices that require access to the interface.

To telnet to the remote device, set the mode parameter to "telnet" and optionally include the port parameter to specify a port. When you set mode to "telnet" but omit the port parameter, the value for port defaults to 23. For persistent connections, define mode and port under the vars: section. For local connections, you can define the parameters either under the vars: section or as module arguments.

The following playbook telnets to a Junos device using port 7016, retrieves the device facts, and saves them to a file. The playbook prompts for the username and password.

The Juniper Networks modules enable you to connect to a Junos device using a serial console connection, which is useful when you must initially configure a new or zeroized device that is not yet configured for remote access. To use this connection method, your terminal or laptop must be physically connected to the Junos device through the CONSOLE port. For detailed instructions about connecting to the CONSOLE port on a Junos device, see the hardware documentation for your specific device.

To connect to a Junos device through a serial console connection, set the module’s mode parameter to "serial", and optionally include the port parameter to specify a port. When you set mode to "serial" but omit the port parameter, the value for port defaults to /dev/ttyUSB0. For persistent connections, define mode and port under the vars: section. For local connections, you can define the parameters either under the vars: section or as module arguments.

The following playbook connects to a Junos device through the CONSOLE port and then loads and commits an initial configuration. The playbook prompts for the username and password.