feeding discovery rule with item values

[Plexus]

Hey there,

we are working with AWS mainly and use burstable EC2 instances at some points. Burstable EC2 instances are virtual machines with CPU credits, which needs to be monitored, due giving an inoperable system if exhausted. We are obtaining this value with a cronjob-script from the AWS API sent to zabbix trapper and having a calculated item based on this trapper for the triggers. As not all instances are burstable those calculated items are extending my not supported items list unnecessary - so I would prefer establishing a discovery rule for this.

I got a template with an item

system.run[curl -s -f http://169.254.169.254/latest/meta-data/instance-type]

giving back t2.medium, t3.medium or t3a.medium for a medium sized, burstable instance for example.

I created discovery rule being dependent on this item but as discovery rules can be fed with JSON only, I added a preprocessing step with JavaScript

return '{"data": {"name": "' + value + '"}}';

This preprocessed JSON is passed to the LDD macro

{#INSTANCE_TYPE} pickup from JSONpath $.name

and finally filtered by

{#INSTANCE_TYPE} matches ^t(2|3a?)\.(nano|micro|small|medium|large|xlarge|2xlarge)$

Finally I added a prototype item dependent on the item mentioned at the beginning associating the appropiate maximum available CPU credits



with JavaScript preprocessing

if (/^t2.nano$/.test(value)) {return 72};
if (/^t(2\.micro|3a?\.nano)$/.test(value)) {return 144};
if (/^t(2\.small|3a?\.micro)$/.test(value)) {return 288};
if (/^t((2|3a?)\.medium|3a?\.small)$/.test(value)) {return 576};
if (/^t(2|3a?).large$/.test(value)) {return 864};
if (/^t2.xlarge$/.test(value)) {return 1296};
if (/^t2.2xlarge$/.test(value)) {return 1958.4};
if (/^t3a?.xlarge$/.test(value)) {return 2304};
if (/^t3a?.2xlarge$/.test(value)) {return 4608};

The discoery rule is reporting no errors although there is no item created.

Please let me know how to proceed.

Greetings,
Plex

[Plexus]

Ok I got it working after realizing that zabbix expects getting back a JSON list - even if filled with one element only.
So the JS part looks like this:

return '[{"name": "' + value + '"}]'

Thanks for your attention ... over and out!