Many services in NSO rely on NEDs to perform network
provisioning. These services map service-specific configuration
to the device data models, provided by the NEDs. As the NED
packages can be upgraded independently, they can introduce changes
in the device YANG models that cause issues for the services using
them.
NSO provides tools to migrate between backwards
incompatible NED versions. The tools are designed to
give you a structured analysis of which paths will change
between two NED versions and visibility into the scope of
the potential impact that a change in the NED will drive in
the service code.
The tools allows for a usage-based analysis of which parts of
the NED data model (and instance tree) a particular
service has written to. This will give you an (at least
opportunistic) sense of which paths must change in the service code.
These features aim to lower the barrier of upgrading NEDs
and significantly reduce the amount of uncertainty and side effects
that NED upgrades were historically associated with.
By using the /ncs:devices/device/migrate action you
can change the NED major/minor version of a device. The
action migrates all configuration and service meta-data.
The action can also be executed in parallel
on a device group or on all devices matching a NED identity.
The procedure for migrating devices is further described in
the section called “NED Migration” in
NSO 5.7 Administration Guide
.
Additionally, the example
examples.ncs/getting-started/developing-with-ncs/26-ned-migration
in the NSO examples collection illustrates how to
migrate devices between different NED versions using the
migrate action.
What makes it particularly useful to a service developer is that
the action reports what paths have been modified and the service
instances affected by those changes. This information can then
be used to prepare the service code to handle the new NED
version. If the verbose option is used, all service
instances are reported instead of just the service points.
If the dry-run option is used, the action simply
reports what it would do. This gives you the chance to do
analysis before any actual change is performed.