topic Re: Example for id-allocation using Templates in NSO Developer Hub Discussions

Example for id-allocation using Templates

gmathewk — Fri, 01 Mar 2019 12:12:31 GMT

Hi Team,

I had some questions about id-allocation using resource-manager package. I wanted to establish the following scenario. I have some interface tunnel configs for IOS device. I want to use id-allocation for assigning the interface number when this template is assigned to a device. Is there a way in the XML template I can request for an allocation and get back the value assigned and use it ?

Do you have any example where you have used allocation ?

Regards

Georgy

Re: Example for id-allocation using Templates

vleijon — Fri, 13 Jul 2018 16:04:51 GMT

Hi Georgy,

Unfortunately, you will have to write a little bit of code to use the id-allocator. You can of course keep your template and apply the template from your code.

--Viktor

Re: Example for id-allocation using Templates

gmathewk — Fri, 13 Jul 2018 17:21:03 GMT

I think i can request for an allocation using Netconf operation. And in the device template can i use the xpath and retrieve the ID allocated for that request ?

Re: Example for id-allocation using Templates

adam.allen — Fri, 13 Jul 2018 19:06:29 GMT

Doesn't the resource-manager package follow the reactive-fast-map pattern, in which case it wouldn't be possible to do in templates alone.

Adam

Re: Example for id-allocation using Templates

vleijon — Fri, 13 Jul 2018 19:32:22 GMT

Hi Adam, it does use RFM. Which was why my instinctive answer was no. But, now that I was challenged on it I am thinking it can actually be done in this simple case. I'll try to whip up an example!

-Viktor

Re: Example for id-allocation using Templates

adam.allen — Fri, 13 Jul 2018 20:17:37 GMT

That would be interesting to see - I was looking at allocating ID's for IP SLA probes - but decided against adding RFM to the service just to get an ID.

Re: Example for id-allocation using Templates

vleijon — Sat, 14 Jul 2018 09:40:24 GMT

First of all - this is not recommended practice! Writing a few lines of code really isn't that bad.

That being said: I made it work!

I setup a simple ncs with the id-allocator, resource-manager packages, and the router ned from the examples directory. Then I did

ncs-make-package --service-skeleton template templ

and compiled the model for templ.

I modified the template a lot, see https://gist.github.com/vleijon/d2dcdffd70bfab7dcaddbdd47196505dfor full template, and created a pool named pool1 (hardcoded name):

set resource-pools id-pool pool1 range start 1 end 100

I can then create services:

admin@ncs% set tmpl demo device ex1

[ok][2018-07-14 11:35:50]

[edit]

admin@ncs% commit dry-run

cli {

    local-node {

        data +tmpl demo {

             +    device [ ex1 ];

             +}

              resource-pools {

                  id-pool pool1 {

             +        allocation demo {

             +            allocating-service /tmpl[name='demo'];

             +        }

                  }

              }

    }

}

[ok][2018-07-14 11:35:52]

[edit]

admin@ncs% commit

Commit complete.

[ok][2018-07-14 11:36:00]

[edit]

admin@ncs% exit

[ok][2018-07-14 11:36:01]

admin@ncs> request tmpl demo get-modifications

cli {

    local-node {

        data devices {

                   device ex1 {

                       config {

                           r:sys {

                               interfaces {

              +                    interface eth5 {

              +                        description "Interface 5";

              +                    }

                               }

                           }

                       }

                   }

               }

               resource-pools {

                   id-pool pool1 {

              +        allocation demo {

              +            allocating-service /tmpl[name='demo'];

              +        }

                   }

               }



    }

}

[ok][2018-07-14 11:36:12]

And this is sort of the desired behaviour, it waits for allocation before applying the template.

Re: Example for id-allocation using Templates

gmathewk — Mon, 16 Jul 2018 18:20:47 GMT

Hi Viktor,

Thanks for the example. I tried this with NSO 4.6.1.3 version. But doesnt seem to work for me. I am using a cisco-ios netsim device, and i dont see the {$val} being used.

Thanks for your help in advance.

Regards

Georgy

Re: Example for id-allocation using Templates

adam.allen — Mon, 16 Jul 2018 19:33:18 GMT

I'd not thought about the new template features, for me I think I'd prefer a little bit of code instead of baking the complexity into the template.

Adam

Re: Example for id-allocation using Templates

vleijon — Tue, 17 Jul 2018 07:08:56 GMT

Georgy: I modified it for ios in the obvious ways (using config trees from the ios ned instead of the router ned),

https://gist.github.com/vleijon/8aba33485ab353ceb24203bd5fab410a and it seems to work fine for me on 4.6.1.

Adam: I agree with you. It is neat that it works, but in most cases I would pick the code route.

Re: Example for id-allocation using Templates

gmathewk — Tue, 17 Jul 2018 13:28:02 GMT

Thanks Viktor. Which version of resource-manager package are you using ?

Regards

Georgy

Re: Example for id-allocation using Templates

vleijon — Tue, 17 Jul 2018 13:50:57 GMT

I was using the versions from the NSO distribution, they don't have any nice version numbers, but are just called example:

admin@ncs> show packages package resource-manager-example

packages package resource-manager-example

package-version 0.0.0.0

description "Resource manager package"

ncs-min-version [ 3.0 ]

directory ./state/packages-in-use/1/resource-manager

oper-status up

Re: Example for id-allocation using Templates

gmathewk — Tue, 17 Jul 2018 14:15:52 GMT

I have NCS - 4.6.1.3 and resource-manager - 3.3.0

admin@ncs% commit dry-run | debug template

Fetching literal "pool1" (from file "tmpl-template.xml", line 😎

Operation 'merge' on existing node: /resource-pools/idalloc:id-pool[name='pool1'] (from file "tmpl-template.xml", line 😎

Evaluating "./name" (from file "tmpl-template.xml", line 10)

Context node: /tmpl[name='vishal']

Result:

For /tmpl[name='vishal'], it evaluates to "vishal"

Operation 'merge' on non-existing node: /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='vishal'] (from file "tmpl-template.xml", line 10)

Operation 'merge' on non-existing node: /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='vishal']/username (from file "tmpl-template.xml", line 11)

Evaluating "./name" (from file "tmpl-template.xml", line 11)

Context node: /tmpl[name='vishal']

Result:

For /tmpl[name='vishal'], it evaluates to "vishal"

Setting /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='vishal']/username to "vishal"

Operation 'merge' on non-existing node: /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='vishal']/allocating-service (from file "tmpl-template.xml", line 12)

Fetching literal "/tmpl:tmpl[tmpl:name='" (from file "tmpl-template.xml", line 12)

Evaluating "./name" (from file "tmpl-template.xml", line 12)

Context node: /tmpl[name='vishal']

Result:

For /tmpl[name='vishal'], it evaluates to "vishal"

Fetching literal "']" (from file "tmpl-template.xml", line 12)

Setting /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='vishal']/allocating-service to "/tmpl:tmpl[tmpl:name='vishal']"

Processing instruction 'set-root-node': changing XPath root node to the datastore root node (from file "tmpl-template.xml", line 23)

Processing instruction 'set': evaluating expression for variable myref (from file "tmpl-template.xml", line 24)

Evaluating "concat('/tmpl:tmpl{',./name,'}')" (from file "tmpl-template.xml", line 24)

Context node: /tmpl[name='vishal']

Result: "/tmpl:tmpl{vishal}"

Processing instruction 'set': evaluating expression for variable val (from file "tmpl-template.xml", line 25)

Evaluating "/id-allocator/pool[name='pool1']/allocation[owner=$myref]" (from file "tmpl-template.xml", line 25)

Context node: /tmpl[name='vishal']

Result: empty node

Processing instruction 'if': evaluating the condition (from file "tmpl-template.xml", line 27)

Evaluating conditional expression "boolean($val)" (from file "tmpl-template.xml", line 27)

Context node: /tmpl[name='vishal']

Result: false - skipping siblings

Processing instruction 'if': skipping (from file "tmpl-template.xml", line 27)

cli {

local-node {

data +tmpl vishal {

+ device [ md1 ];

resource-pools {

id-pool pool1 {

+ allocation vishal {

+ username vishal;

+ allocating-service /tmpl[name='vishal'];

+ }

}

Re: Example for id-allocation using Templates

gmathewk — Tue, 17 Jul 2018 14:20:12 GMT

Also the config template you used the key 'owner'

<?set val = {/id-allocator/pool[name='pool1']/allocation[owner=$myref]}?>

But i dont see that in the xpath.

admin@ncs> show resource-pools | display xpath

/resource-pools/idalloc:id-pool[name='pool1']/allocation[id='cc']/response/id 102

/resource-pools/idalloc:id-pool[name='pool1']/allocation[id='demo']/response/id 100

/resource-pools/idalloc:id-pool[name='pool1']/allocation[id='denis']/response/id 103

/resource-pools/idalloc:id-pool[name='pool1']/allocation[id='gmk']/response/id 10

Re: Example for id-allocation using Templates

vleijon — Tue, 17 Jul 2018 14:22:37 GMT

First of all, you are looking at the wrong place, try

show id-allocator | display xpath

Second of all, in commit dry-run, you shouldn't expect to see a value for val, because the id-allocator hasn't had a chance to allocate it yet.

Re: Example for id-allocation using Templates

gmathewk — Tue, 17 Jul 2018 14:27:50 GMT

I see the allocation happening. But get-modifications does not show anything

admin@ncs> request tmpl vishal get-modifications

cli {

local-node {

data resource-pools {

id-pool pool1 {

+ allocation vishal {

+ username vishal;

+ allocating-service /tmpl[name='vishal'];

+ }

}

Re: Example for id-allocation using Templates

vleijon — Tue, 17 Jul 2018 14:31:51 GMT

After you have done that commit, and have the allocation there, try doing a re-deploy | debug template.

Re: Example for id-allocation using Templates

gmathewk — Tue, 17 Jul 2018 14:41:54 GMT

admin@ncs> show resource-pools

NAME ID ERROR ID

----------------------

pool1 g1 - 1

g2 - 2

[ok][2018-07-17 10:38:33]

admin@ncs> show id-allocator

NAME START END START END START END ID

-----------------------------------------------

pool1 - - 3 10 1

admin@ncs% request tmpl g2 re-deploy | debug template

Fetching literal "pool1" (from file "tmpl-template.xml", line 😎

Operation 'merge' on existing node: /resource-pools/idalloc:id-pool[name='pool1'] (from file "tmpl-template.xml", line 😎

Evaluating "./name" (from file "tmpl-template.xml", line 10)

Context node: /tmpl[name='g2']

Result:

For /tmpl[name='g2'], it evaluates to "g2"

Operation 'merge' on non-existing node: /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='g2'] (from file "tmpl-template.xml", line 10)

Operation 'merge' on non-existing node: /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='g2']/username (from file "tmpl-template.xml", line 11)

Evaluating "./name" (from file "tmpl-template.xml", line 11)

Context node: /tmpl[name='g2']

Result:

For /tmpl[name='g2'], it evaluates to "g2"

Setting /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='g2']/username to "g2"

Operation 'merge' on non-existing node: /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='g2']/allocating-service (from file "tmpl-template.xml", line 12)

Fetching literal "/tmpl:tmpl[tmpl:name='" (from file "tmpl-template.xml", line 12)

Evaluating "./name" (from file "tmpl-template.xml", line 12)

Context node: /tmpl[name='g2']

Result:

For /tmpl[name='g2'], it evaluates to "g2"

Fetching literal "']" (from file "tmpl-template.xml", line 12)

Setting /resource-pools/idalloc:id-pool[name='pool1']/allocation[id='g2']/allocating-service to "/tmpl:tmpl[tmpl:name='g2']"

Processing instruction 'set-root-node': changing XPath root node to the datastore root node (from file "tmpl-template.xml", line 23)

Processing instruction 'set': evaluating expression for variable myref (from file "tmpl-template.xml", line 24)

Evaluating "concat('/tmpl:tmpl{',./name,'}')" (from file "tmpl-template.xml", line 24)

Context node: /tmpl[name='g2']

Result: "/tmpl:tmpl{g2}"

Processing instruction 'set': evaluating expression for variable val (from file "tmpl-template.xml", line 25)

Evaluating "/id-allocator/pool[name='pool1']/allocation[owner=$myref]" (from file "tmpl-template.xml", line 25)

Context node: /tmpl[name='g2']

Result: empty node

Processing instruction 'if': evaluating the condition (from file "tmpl-template.xml", line 27)

Evaluating conditional expression "boolean($val)" (from file "tmpl-template.xml", line 27)

Context node: /tmpl[name='g2']

Result: false - skipping siblings

Processing instruction 'if': skipping (from file "tmpl-template.xml", line 27)

[ok][2018-07-17 10:41:40]

[edit]

admin@ncs%

System message at 2018-07-17 10:41:40...

Commit performed by admin via console using cli.

Re: Example for id-allocation using Templates

gmathewk — Tue, 17 Jul 2018 14:44:52 GMT

I was checking the xpath.

admin@ncs> show id-allocator | display xpath

/id-allocator/pool[name='pool1']/available[start='3'][end='10']

/id-allocator/pool[name='pool1']/allocation[id='1']

/id-allocator/pool[name='pool1']/allocation[id='2']

Re: Example for id-allocation using Templates

vleijon — Tue, 17 Jul 2018 15:08:54 GMT

Yeah. That is a difference in your id-allocator. It doesn't seem to contain the owner in the allocation pool.

It might be possible to make it work using the resource-pool path instead, using a query like the one in the comment in the template. But, I am not entirely sure how.

I would recommend just breaking the allocation out into python code.