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Custom Metrics

Canary checker can export custom metrics from any check type, replacing and/or consolidating multiple standalone Prometheus Exporters into a single exporter.

In the example below, exchange rates against the USD are exported by first calling an HTTP api and then using the values from the JSON response to create the metrics:

exchange-rates-exporter.yaml
apiVersion: canaries.flanksource.com/v1
kind: Canary
metadata:
name: exchange-rates
spec:
schedule: "every 30 @minutes"
http:
- name: exchange-rates
url: https://api.frankfurter.app/latest?from=USD&to=GBP,EUR,ILS
metrics:
- name: exchange_rate
type: gauge
value: json.rates.GBP
labels:
- name: "from"
value: "USD"
- name: to
value: GBP

- name: exchange_rate
type: gauge
value: json.rates.EUR
labels:
- name: "from"
value: "USD"
- name: to
value: EUR

- name: exchange_rate
type: gauge
value: json.rates.ILS
labels:
- name: "from"
value: "USD"
- name: to
value: ILS
- name: exchange_rate_api
type: histogram
value: elapsed.getMilliseconds()

Which would output:

exchange_rate{from=USD, to=GBP} 0.819
exchange_rate{from=USD, to=EUR} 0.949
exchange_rate{from=USD, to=ILS} 3.849
exchange_rate_api 260.000

Result Variables

FieldDescriptionSchemeRequired
metricsMetrics to export from check resultsMetric

Metric

FieldDescriptionSchemeRequired
nameName of the metricstringYes
valueAn expression to derive the metric value fromExpressionYes
typePrometheus Metric Type (counter, gauge or histogram)stringYes
labelsLabels for prometheus metric (values can be templated)[]Label

Label

FieldDescriptionSchemeRequired
nameName of the labelstringYes
valueA static value for the headerstring
valueExprAn expression to derive the header value fromExpression
labelsLabels for prometheus metric (values can be templated)map[string]string

Expressions can make use of the following variables:

Expression Variables

FieldsDescriptionScheme
resultCheck ResultSee result variables section of the check
last_result.resultsThe last result
check.nameCheck namestring
check.descriptionCheck descriptionstring
check.labelsDynamic labels attached to the checkmap[string]string
check.endpointEndpoint (usually a URL)string
check.durationDuration in millisecondsint64
canary.nameCanary namestring
canary.namespaceCanary namespacestring
canary.labelsLabels attached to the canary CRD (if any)map[string]string