"Service Upgrade" with Python available?

[mleske]

Hello folks,

I am wondering whether there is a chance to have python code supporting Service Upgrade phase, e.g. after the YANG model has changed and existing services need to be corrected. Example "developing-with-ncs/14-upgrade-service" only shows this with Java code.

According to Roque, I want to know if there is “setUseForCdbUpgrade” in Python API.

If possible getting an example comparable to 14-upgrade-service would be great.

Regards

Mike

[mleske]

Any idea or example already available?

[Jan Lindblad · Accepted solution]

Here's a small example to illustrate this.

I made an upgrade function that rounds down the 'val' leaf to the nearest multiple of 4. I did not write any code that checks whether the package was launched due to a software upgrade, or checks if the conversion has been done already. A real upgrade package would typically need something to control that. The exact details may vary.

Anyway, here I have a tiny service with a single leaf 'val'. In this example, there are three instances as shown in the CLI output. Then I reload the package which runs the upgrade code, and ensures all values are multiples of 4. Then I show the configured values again.

admin@ncs# show running-config upp

upp abba

val 14

!

upp dep

val 16

!

upp enya

val 29

!

admin@ncs# packages reload

reload-result {

    package upp

    result true

}

admin@ncs#

System message at 2017-09-01 16:26:07...

Commit performed by admin via tcp using python.

admin@ncs# show running-config upp

upp abba

val 12

!

upp dep

val 16

!

upp enya

val 28

!

To make this happen, I have two components in package-meta-data.xml . One for the service itself, and one for the upgrade function.

  <component>

    <name>main</name>

    <application>

      <python-class-name>upp.main.Main</python-class-name>

    </application>

  </component>

  <component>

    <name>upgrade</name>

    <application>

      <python-class-name>upgrade.main.Main</python-class-name>

    </application>

  </component>

</ncs-package>

My packages/upp/python/upgrade/main.py look like this:

# -*- mode: python; python-indent: 4 -*-

import ncs

from ncs.application import Service

# ---------------------------------------------

# COMPONENT THREAD THAT WILL BE STARTED BY NCS.

# ---------------------------------------------

class Main(ncs.application.Application):

    def setup(self):

       self.log.info('Upgrade Main RUNNING')

        with ncs.maapi.Maapi() as m:

            with ncs.maapi.Session(m, 'admin', 'python'):

                with m.start_write_trans() as t:

                    root = ncs.maagic.get_root(t)

                    for upp in root.upp:

                     self.log.info('Found upp instace with val=',upp.val)

                      upp.val = upp.val & ~3

                     self.log.info('Rouinding down to multiple of 4, new val=',upp.val)

                    t.apply(keep_open=False)

    def teardown(self):

       self.log.info('Upgrade Main FINISHED')

I'll figure out how to post the complete mini-example if anyone asks for it.