Kapacitor templates using string concatenation fails to define

InfluxDB 1 Kapacitor
1

Hello,

I’m uisng Kapacitor templates to make my alerts and know i can use syntax like {{if eq .Level “WARNING”}} show something {{else if eq .Level “CRITICAL”}} show something else {{end}} I also know i can include the values of my variables in my scripts with string concatination, however the two don’t seem to work in conjunction.

I need to send a message out based on the level and then show the value for the variable.

So i have a message like

var message = '{{index .Tags "host_name"}} Nutanix Alert: Memory Usage over the threshold ' + string(threshold) + '% for over {{if eq .Level "WARN"}} ' + string(warn) + '{{else if eq .Level "CRIT"}}' + string(crit) + ' Minutes. {{end}}'

I also tried changing it to + float(threshold) but it didn’t seem to do anything. Whenever i define the template i get the following error

invalid TICKscript: Failed to handle left node: Failed to handle right node: Failed to handle node: Given node type is not valid evaluation node: <nil>

Tick script:
var db = ‘Database’

var rp = 'autogen'

var measurement string

var groupBy = ['host_name','host_uuid','cluster_uuid','host','vm_name','vm_uuid']
var host string
var priority string
var threshold lambda
var whereFilter = lambda: ("host_name" == host OR "vm_name" == host)

// The threshold for the alert to begin processing and triggering the alert. An alert is generated when warning/critical time values are exceeded
// This value is a percentage: 98% should be entered as 98.0

var name = 'NutanixMemoryUsage' + priority

var idVar = name + '{{index .Tags "host_name"}} {{ index .Tags "vm_name"}}'

var idTag = 'alertID'

var levelTag = 'level'

var messageField = 'message'

var durationField = 'duration'

var outputDB = 'alerts'

var outputRP = 'autogen'

var outputMeasurement = 'NutanixAlerts'

var triggerType = 'threshold'


// Critical alert: time based, alert after the specified time (in 1 minute units).
// 10 Minutes should be entered as 10
var crit lambda
// Warning alert: time based, alert after the specified time (in 1 minute units).
// 5 Minutes should be entered as 5
var warn lambda
var message = '{{index .Tags "host_name"}} Nutanix Alert: Memory Usage over the threshold ' + string(threshold) + '% for over {{if eq .Level "WARN"}} ' + string(warn) + '{{else if eq .Level "CRIT"}}' + string(crit) + ' Minutes. {{end}}'

var data = stream
    |from()
        .database(db)
        .retentionPolicy(rp)
        .measurement(measurement)
        .groupBy(groupBy)
        .where(whereFilter)
 
    |eval(lambda: ("memory_usage_ppm"),
          lambda: ("memory_usage_ppm" / 10000))
        .as('memory_usage_ppm','memory_used')
        .keep('memory_usage_ppm', 'memory_used')
    |stateDuration(lambda: "memory_used" >= threshold)
        .unit(1m)
        .as('warn_duration')
    |stateDuration(lambda: "memory_used" >= threshold)
        .unit(1m)
        .as('crit_duration')


var trigger = data
    |alert()
        .crit(lambda: "crit_duration" >= crit)
        .warn(lambda: "warn_duration" >= warn)
        .stateChangesOnly()
        .message(message)
        .id(idVar)
        .idTag(idTag)
        .levelTag(levelTag)
        .messageField(messageField)
        .durationField(durationField)
        .log('/tmp/' + name + '.log')

trigger
    |eval(lambda: float("memory_used"),
          lambda: float("memory_usage_ppm"))
        .as('memory_used','memory_usage_ppm')
        .keep()
    |influxDBOut()
        .create()
        .database(outputDB)
        .retentionPolicy(outputRP)
        .measurement(outputMeasurement)
        .tag('alertName', name)
        .tag('Priority', priority)
        .tag('triggerType', triggerType)

trigger
    |httpOut('output')

I’m not sure whether I’ve got something wrong here or whether or not it’s possible to combine both the template functions and concatenation. Is there a way to do this?

Thanks

Phil