Is there a way to get "commit dry-run" from python?

[cnicasio]

Hi, it would be very useful for a code I'm writing in Python, to be able to get "commit dry-run outfomat xml" like output in python.

The code is like

...

with ncs.maapi.single_write_trans('admin', 'python') as t:
   ....
   several maagic writes to CDB
   ...

At this point, before applying the transaction, I would lke to get CLI o XML output similar to "commit dry-run..." on the NSO CLI..

I tried t.apply with COMMIT_NCS_DRY_RUN_XML flag, but didn't get any result..

Anybody knows if that is possible?

Regards

[vleijon]

If you use apply_params it ought to work.

[cnicasio]

Thanks a lot...I don't find documentation on that function...would be nice if you have an example

[vleijon]

It is documented in the main python documentation, so you can do pydoc ncs.maapi.Transaction.apply_params. But, I think essentially it works the way you wanted apply to work, set flags to dry run and it will return a dictionary with dry-run results in it.

[lmanor]

You can find apply_params() pydocs here: nso-5.2.0.1/doc/api/python/ncs.maapi.html

CommitParams class here: nso-5.2.0.1/src/ncs/pyapi/pysrc/maapi.py

Using CommitParams() along with apply_params() you can do dry-run like this:

...: cp = ncs.maapi.CommitParams()

...: cp.dry_run_native()

#...: cp.dry_run_cli()

#...: cp.dry_run_native()

#...: cp.dry_run_xml()

...: r = t.apply_params(True, cp)

...: print r

...:

{'device': {'ios-1': '\n\nhostname Test_75\n'}, 'outformat': 'native', 'dry-run': True}

[cnicasio]

OK! thanks a lot for your help!

[Johan Nemitz]

Is there a way to do this in a service? I attempted to get the transaction of the service and follow this approach but I am getting:
r = t.apply_params(True, cp)
File "/root/nso/nso-versions/5.2.1/src/ncs/pyapi/ncs/tm.py", line 12, in wrapper
return fn(*args, **kwargs)
File "/root/nso/nso-versions/5.2.1/src/ncs/pyapi/ncs/maapi.py", line 1325, in apply_params
tvresult = self.maapi.apply_trans_params(self.th, keep_open, tvparams)
File "/root/nso/nso-versions/5.2.1/src/ncs/pyapi/ncs/maapi.py", line 273, in proxy
return real(self2.msock, *args, **kwargs)
Error: Bad protocol usage or unexpected retval (21): not allowed for attached transaction

Thanks!

[lmanor]

HI Johan,

I don't recognize the this exact error, but usually it is not prudent to apply a transaction 'inside' of a transaction - tends to get into a transaction lock deadlock situation.

See this thread previous thread on a similar:

https://community.cisco.com/t5/nso-developer-hub-discussions/call-partial-sync-from-function-in-cb-create/td-p/3895272

Presumably, you are attempting to save off the dry-run config that is getting written to the network. I've seen this done through a 2-step action, does a transaction for the dry-run followed by a transaction for the actual service instance commit. Also seen it done via a custom cli command that issues subsequent commit-dry-run and commit commands. I'm sure a reactive fastmap service could be crafted to do the dry-run/commit sequence as well.

[mohamkh7]

Hi Imanor,
As per above logic, t.apply_params(True, cp) will always commit the transaction.

We have 1 scenario where we just need to show dry-run output without doing actual commit from an action.
So is it possible to do so ?
We are aware of the old way by using services commit-dry-run like below
```

dryRun = root.ncs__services.commit_dry_run

dryRunInp = dryRun.get_input()

dryRunInp.outformat = 'cli'

dryRunResult = dryRun(dryRunInp)

cliDryRun = dryRunResult.cli.local_node.data

```

However since it is deprecated; we are looking for new way.

Thanks in advance

[lmanor]

Hello, 

I am not seeing the behavior that you see, the dry-run commit is _not_ committed to the running-config:

[edit]
admin@ncs% show devices device ios-1 config ios:hostname
ios:hostname TEST1;
[ok][2020-11-04 11:13:30]

In [8]: with ncs.maapi.Maapi() as m:
...: with ncs.maapi.Session(m, 'admin', 'system'):
...: with m.start_write_trans() as t:
...: root = ncs.maagic.get_root(t)
...: name = 'ios-1'
...: dev = root.ncs__devices.device['ios-1']
...: dev.config.ios__hostname = 'Test_82'
...: cp = ncs.maapi.CommitParams()
...: cp.dry_run_cli()
...: r = t.apply_params(True, cp)
...: print (r)
...:
{'dry-run': True, 'outformat': 'cli', 'local-node': ' devices {\n device ios-1 {\n config {\n- ios:hostname TEST1;\n+ ios:hostname Test_82;\n }\n }\n }\n'}

[edit]
admin@ncs% show devices device ios-1 config ios:hostname
ios:hostname TEST1;
[ok][2020-11-04 11:14:04]

In [9]: with ncs.maapi.Maapi() as m:
...: with ncs.maapi.Session(m, 'admin', 'system'):
...: with m.start_write_trans() as t:
...: root = ncs.maagic.get_root(t)
...: name = 'ios-1'
...: dev = root.ncs__devices.device['ios-1']
...: dev.config.ios__hostname = 'Test_82'
...: cp = ncs.maapi.CommitParams()
...: cp.dry_run_xml()
...: r = t.apply_params(True, cp)
...: print (r)
...:
{'dry-run': True, 'outformat': 'xml', 'local-node': '<devices xmlns="http://tail-f.com/ns/ncs">\n <device>\n <name>ios-1</name>\n <config>\n <hostname xmlns="urn:ios">Test_82</hostname>\n </config>\n </device>\n</devices>\n'}

[edit]
admin@ncs% show devices device ios-1 config ios:hostname
ios:hostname TEST1;
[ok][2020-11-04 11:14:44]

In [10]: with ncs.maapi.Maapi() as m:
...: with ncs.maapi.Session(m, 'admin', 'system'):
...: with m.start_write_trans() as t:
...: root = ncs.maagic.get_root(t)
...: name = 'ios-1'
...: dev = root.ncs__devices.device['ios-1']
...: dev.config.ios__hostname = 'Test_82'
...: cp = ncs.maapi.CommitParams()
...: cp.dry_run_native()
...: r = t.apply_params(True, cp)
...: print (r)
{'dry-run': True, 'outformat': 'native', 'device': {'ios-1': '\n\nhostname Test_82\n'}}

[edit]
admin@ncs% show devices device ios-1 config ios:hostname
ios:hostname TEST1;
[ok][2020-11-04 11:16:49]

[W. Y.]

I have the same problem. NSO Version 5.6.4

[mohamkh7]

Got it Thanks. 

[ben_piret]

Hi all,

I am looking to access the Commit Parameters (dry-run, no-networking, etc) in the cb_create or in the service pre_modification.

I simply tried this :

    @service.pre_modification

    def cb_pre_modification(self, tctx, op, kp, root, proplist

        with ncs.maagic.get_trans(root) as t :

            cp = ncs.maapi.CommitParams()

            self.log.info("commit parameters : {}".format(cp))

But it does not really work -

I don't want to modify the commit parameters but I 'd like to do a test in python later in the code if the transaction is made with 'no-networking' option. 

Any idea on how to do that ?

Benoit

[ben_piret]

Hi,

just to follow-up .

The answer is there for NSO >5.5 : Solved: Re: How to check if it is a dry-run in python for a service - Cisco Community

Benoit