Use Junos PyEZ to Install Software on Junos Devices

When you use Junos PyEZ to install software on Junos devices, you can download the software image to the configuration management server, and the install() method, by default, copies it to the target device before performing the installation. You can also instruct the install() method to install an image that already resides on the target device or resides at a URL that is reachable from the target device.

Table 1 outlines the install() method parameters that you must set depending on the software package location. You must always include either the package or pkg_set parameter in the install() method invocation.

Table 1: install() Method Parameter Settings for Software Package Location

Software Package Location	no_copy Parameter	package or pkg_set Parameter	remote_path Parameter
Configuration management server	Omit or set to False	File path including the filename of the software package or packages on the local server running Junos PyEZ.	(Optional) Path to the directory on the target device to which the package or packages will be copied. Default is /var/tmp.
Target device	Set to True	Filename of the software package or packages.	(Optional) Path to the directory on the target device where the package or packages must already reside. Default is /var/tmp.
URL	–	URL from the perspective of the target Junos device from which the software package is installed.	–

The package argument is used to install software on a single Junos device or on members in a non-mixed Virtual Chassis. The package argument is a string that specifies a single software image. For example:

The pkg_set argument is used to install software on the members in a mixed Virtual Chassis. It contains a list or tuple of strings that specify the necessary software images, in no particular order, for the various Virtual Chassis members. For example:

For packages residing on the local server running Junos PyEZ, when you omit the no_copy argument or set it to False, the server copies the specified software package to the device. Including the package argument causes the server to copy the package to the target device (individual device or primary router or switch in a non-mixed Virtual Chassis), and including the pkg_set argument causes the server to copy all packages in the list to the primary router or switch in a mixed Virtual Chassis. By default, software images are placed in the /var/tmp directory unless the remote_path argument specifies a different directory.

If you set the no_copy argument to True, the necessary software packages must already exist on the target device or Virtual Chassis primary device before the installation begins. The packages must reside either in the directory specified by the remote_path argument, or if remote_path is omitted, in the default /var/tmp directory.

Junos PyEZ also supports installing software images from a URL. In this case, the package or pkg_set value must be a URL from the perspective of the target Junos device. The package is copied over and installed from the specified URL, and the no-copy and remote_path arguments are ignored. For information about specifying the format of the URL, see Format for Specifying Filenames and URLs in Junos OS CLI Commands.

To install a software image on a Junos device, a Junos PyEZ application connects to the individual device or to the primary device in a Virtual Chassis, creates an instance of the SW utility, and calls the install() method with any required or optional arguments. For example:

For the current list of install() method parameters, see install().

If the software package is located on the configuration management server, and the no_copy parameter is omitted or set to False, the install() method performs the following operations before installing the software:

• Computes the checksum of the local software package or packages using the algorithm specified in the checksum_algorithm argument, if the checksum is not already provided through the checksum argument. Acceptable checksum_algorithm values are "md5", "sha1", and "sha256". The default is "md5".

• Performs a storage cleanup on the target device to create space for the software package, unless cleanfs is set to False.

• SCP or FTP copies the package to the remote_path directory, or if remote_path is not specified, to the /var/tmp directory, if a file with the same name and checksum does not already reside in the target location on the device.

• Computes the checksum of the remote file and compares it to the value of the local file.

After the software package is on the target device, whether downloaded there initially, copied over from the configuration management server by the install() method, or copied from a URL by the target device, the install() method performs the following operations:

• Validates the configuration against the new package if the validate parameter is set to True

• Installs the package on all Routing Engines unless all_re is set to False

Note:

Starting in Release 2.1.5, Junos PyEZ, by default, upgrades all Routing Engines on individual devices and members in a Virtual Chassis. In earlier releases, or if all_re=False, Junos PyEZ only upgrades the Routing Engine to which it is connected.

Starting in Junos PyEZ Release 2.5.0, the install() method returns a tuple that contains the status of the installation and a message string. In earlier releases, the method returns only the status of the installation. The status is True if the installation is successful and False otherwise. The message string provides additional information about the success or failure of the installation and can include informational messages or error messages that are generated by Junos PyEZ or the device. For example:

The install() method does not automatically reboot the device. To reboot or shut down the device after the installation is complete, call the reboot() or shutdown() method, respectively.

The following video presents a short Python session that demonstrates how to use Junos PyEZ to install Junos OS.

Junos PyEZ performs operations over a NETCONF session. The default time for a NETCONF RPC to time out is 30 seconds. During the installation process, Junos PyEZ increases the RPC timeout interval to 1800 seconds (30 minutes) when copying and installing the package on the device and to 300 seconds (5 minutes) when computing the checksum. In some cases, the installation process or checksum calculation might exceed these time intervals.

To increase the timeout value for the installation process and the checksum calculation, include the timeout and checksum_timeout parameters, respectively, in the call to the install() method, and set them to appropriate values. For example:

The Junos PyEZ install process enables you to display or log the progress of the installation by including the progress argument in the install() method call. The argument is set to a callback function, which must have a function prototype defined that includes the Device instance and report string arguments. You can also set progress=True to use sw.progress() for basic reporting.

The following example prints the installation progress using the myprogress function.

The progress output is in the user-defined format.

On devices that have Routing Engines with VM host support, Junos OS runs as a virtual machine (VM) over a Linux-based host (VM host). A VM host upgrade requires a VM Host Installation Package (junos-vmhost-install-x.tgz) and upgrades the host OS and compatible Junos OS. The upgrade is performed using the request vmhost software add operational mode command, which corresponds to the <request-vmhost-package-add> RPC.

Starting in Junos PyEZ Release 2.1.6, the sw.install() method supports the vmhost=True argument for performing a VM host upgrade. When the vmhost=True argument is present, the sw.install() method performs the installation using the <request-vmhost-package-add> RPC instead of the <request-package-add> RPC.

The following example upgrades and reboots both the Junos OS and host OS on a single Routing Engine device:

To reboot just the Junos OS software, call the sw.reboot() method without the vmhost argument.

Junos PyEZ provides support for performing a unified in-service software upgrade (unified ISSU) or a nonstop software upgrade (NSSU) on devices that support the feature and meet the necessary requirements. Table 2 outlines the Junos PyEZ release in which the unified ISSU and NSSU features are first supported. For more information about unified ISSU and NSSU, see the software documentation for your product.

Table 2: Junos PyEZ Unified ISSU and NSSU Support

Junos PyEZ Release	Feature Support
2.1.0	Support for unified ISSU and NSSU on dual-Routing Engine Junos devices.
2.1.6	Support for unified ISSU during a VM host upgrade for those devices with VM host support that use the request vmhost software in-service-upgrade command to perform a unified in-service software upgrade of the host OS and Junos OS.

The unified ISSU feature enables you to upgrade between two different Junos OS releases with no disruption on the control plane and with minimal disruption of traffic. To perform a unified in-service software upgrade on devices that support this feature, include the issu=True argument in the install() method.

In the the following example, the install() method upgrades Junos OS on both Routing Engines and reboots the new primary Routing Engine (previously the old backup Routing Engine) as part of the installation process. If the installation is successful, the reboot() method then reboots the connected Routing Engine, which is the new backup Routing Engine (previously the old primary Routing Engine).

To perform a unified in-service software upgrade on a Routing Engine with VM host support that meets the necessary requirements and supports unified ISSU, include the vmhost=True and issu=True arguments in the install() method. The device upgrades from one host OS and Junos OS release to the requested release using the <request-vmhost-package-in-service-upgrade> RPC.

The NSSU feature enables you to upgrade the Junos OS software running on a switch or Virtual Chassis with redundant Routing Engines with minimal disruption to network traffic. To perform a nonstop software upgrade on devices that support this feature, include the nssu=True argument in the install() method. For example:

Generally, when you upgrade a non-mixed EX Series Virtual Chassis, you follow the installation process outlined in Installation Process Overview to upgrade the entire Virtual Chassis. However, there might be times when you need to install software on specific member switches in a Virtual Chassis. Starting in Junos PyEZ Release 2.6.8, you can install a software package on individual member switches in an EX Series Virtual Chassis by using the member_id argument. The member_id argument is a list of strings specifying the member IDs on which to install the software.

For example, the following Junos PyEZ application upgrades the software on member 0 and member 1 in the EX Series Virtual Chassis: