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Scale applications based on Prometheus.

Availability: v1.0+ Maintainer: Community
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Trigger Specification

This specification describes the prometheus trigger that scales based on a Prometheus.

triggers:
- type: prometheus
  metadata:
    # Required
    serverAddress: http://<prometheus-host>:9090
    metricName: http_requests_total
    query: sum(rate(http_requests_total{deployment="my-deployment"}[2m])) # Note: query must return a vector/scalar single element response
    threshold: '100'

Parameter list:

  • serverAddress - Address of Prometheus server. If using VictoriaMetrics cluster version, set full URL to Prometheus querying API, e.g. http://<vmselect>:8481/select/0/prometheus
  • metricName - Metric name to use.
  • query - Query to run.
  • threshold - Value to start scaling for.

Authentication Parameters

Prometheus Scaler supports three types of authentication - bearer authentication, basic authentication and TLS authentication.

You can use TriggerAuthentication CRD to configure the authentication. It is possible to specify multiple authentication types i.e. authModes: "tls,basic" Specify authModes and other trigger parameters along with secret credentials in TriggerAuthentication as mentioned below:

Bearer authentication:

  • authModes: It must contain bearer in case of Bearer Authentication. Specify this in trigger configuration.
  • bearerToken: The token needed for authentication. This is a required field.

Basic authentication:

  • authModes: It must contain basic in case of Basic Authentication. Specify this in trigger configuration.
  • username - This is a required field. Provide the username to be used for basic authentication.
  • password - Provide the password to be used for authentication. For convenience, this has been marked optional, because many applications implement basic auth with a username as apikey and password as empty.

TLS authentication:

  • authModes: It must contain tls in case of TLS Authentication. Specify this in trigger configuration.
  • ca - Certificate authority file for TLS client authentication.
  • cert - Certificate for client authentication. This is a required field.
  • key - Key for client authentication. Optional. This is a required field.

💡 **NOTE:**It’s also possible to set the CA certificate regardless of the selected authModes (also without any authentication). This might be useful if you are using an enterprise CA.

Example 

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: prometheus-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: my-deployment
  triggers:
  - type: prometheus
    metadata:
      serverAddress: http://<prometheus-host>:9090
      metricName: http_requests_total
      threshold: '100'
      query: sum(rate(http_requests_total{deployment="my-deployment"}[2m]))

Here is an example of a prometheus scaler with Basic Authentication, define the Secret and TriggerAuthentication as follows

apiVersion: v1
kind: Secret
metadata:
  name: keda-prom-secret
  namespace: default
data:
  bearerToken: "BEARER_TOKEN"
  ca: "CUSTOM_CA_CERT"
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-prom-creds
  namespace: default
spec:
  secretTargetRef:
    - parameter: bearerToken
      name: keda-prom-secret
      key: bearerToken
      # might be required if you're using a custom CA
    - parameter: ca
      name: keda-prom-secret
      key: ca
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: prometheus-scaledobject
  namespace: keda
  labels:
    deploymentName: dummy
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: dummy
  triggers:
    - type: prometheus
      metadata:
        serverAddress: http://<prometheus-host>:9090
        metricName: http_requests_total
        threshold: '100'
        query: sum(rate(http_requests_total{deployment="my-deployment"}[2m]))
        authModes: "bearer"
      authenticationRef:
        name: keda-prom-creds

Here is an example of a prometheus scaler with Basic Authentication, define the Secret and TriggerAuthentication as follows

apiVersion: v1
kind: Secret
metadata:
  name: keda-prom-secret
  namespace: default
data:
  username: "username"
  password: "password"
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-prom-creds
  namespace: default
spec:
  secretTargetRef:
    - parameter: username
      name: keda-prom-secret
      key: username
    - parameter: password
      name: keda-prom-secret
      key: password
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: prometheus-scaledobject
  namespace: keda
  labels:
    deploymentName: dummy
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: dummy
  triggers:
    - type: prometheus
      metadata:
        serverAddress: http://<prometheus-host>:9090
        metricName: http_requests_total
        threshold: '100'
        query: sum(rate(http_requests_total{deployment="my-deployment"}[2m]))
        authModes: "basic"
      authenticationRef:
        name: keda-prom-creds

Here is an example of a prometheus scaler with TLS Authentication, define the Secret and TriggerAuthentication as follows

apiVersion: v1
kind: Secret
metadata:
  name: keda-prom-secret
  namespace: default
data:
  cert: "cert"
  key: "key"
  ca: "ca"
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-prom-creds
  namespace: default
spec:
  secretTargetRef:
    - parameter: cert
      name: keda-prom-secret
      key: cert
    - parameter: key
      name: keda-prom-secret
      key: key
    - parameter: ca
      name: keda-prom-secret
      key: ca
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: prometheus-scaledobject
  namespace: keda
  labels:
    deploymentName: dummy
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: dummy
  triggers:
    - type: prometheus
      metadata:
        serverAddress: http://<prometheus-host>:9090
        metricName: http_requests_total
        threshold: '100'
        query: sum(rate(http_requests_total{deployment="my-deployment"}[2m]))
        authModes: "tls"
      authenticationRef:
        name: keda-prom-creds

Here is an example of a prometheus scaler with TLS and Basic Authentication, define the Secret and TriggerAuthentication as follows

apiVersion: v1
kind: Secret
metadata:
  name: keda-prom-secret
  namespace: default
data:
  cert: "cert"
  key: "key"
  ca: "ca"
  username: "username"
  password: "password"
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-prom-creds
  namespace: default
spec:
  secretTargetRef:
    - parameter: cert
      name: keda-prom-secret
      key: cert
    - parameter: key
      name: keda-prom-secret
      key: key
    - parameter: ca
      name: keda-prom-secret
      key: ca
    - parameter: username
      name: keda-prom-secret
      key: username
    - parameter: password
      name: keda-prom-secret
      key: password
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: prometheus-scaledobject
  namespace: keda
  labels:
    deploymentName: dummy
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: dummy
  triggers:
    - type: prometheus
      metadata:
        serverAddress: http://<prometheus-host>:9090
        metricName: http_requests_total
        threshold: '100'
        query: sum(rate(http_requests_total{deployment="my-deployment"}[2m]))
        authModes: "tls,basic"
      authenticationRef:
        name: keda-prom-creds