Etcd | KEDA

Scale applications based on an etcd key-value pair. By watching an etcd key, a passively received push mode, the scaler can activate applications with lower load usage than frequent pull mode

Availability: v2.9+ Maintainer: Huawei Cloud

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Trigger Specification

This specification describes the etcd trigger that scales based on an etcd key-value pair.

  triggers:
    - type: etcd
      metadata:
        endpoints: 172.0.0.1:2379,172.0.0.2:2379,172.0.0.3:2379
        watchKey: length
        value: '5.5'
        activationValue: '0.5'
        watchProgressNotifyInterval: '600'
        usernameFromEnv: <admin-user>  # Optional
        passwordFromEnv: <admin-password> # Optional

Parameter list:

endpoints - Etcd servers’ endpoints information. It supports multiple endpoints split by a comma character (,).
watchKey - Name of the etcd key used for the scaler client to get/watch the etcd value from etcd servers.
value - Target relation between the scaled workload and the etcd value. It will be calculated following this formula: relation = (etcd value) / (scaled workload pods). (This value can be a float)
activationValue - Target value for activating the scaler. Learn more about activation here.(Default: 0, Optional, This value can be a float)
watchProgressNotifyInterval - Set this parameter to the same as --experimental-watch-progress-notify-interval parameter of etcd servers. (Default: 600, units are seconds, Optional)
usernameFromEnv - Provide admin username from env instead of as a secret. (Optional)
passwordFromEnv - Provide admin password from env instead of as a secret. (Optional)

Authentication Parameters

You can use TriggerAuthentication CRD to configure the authenticate by tls. It is required you should set tls to enable. If required for your etcd configuration, you may also provide a ca, cert, key and keyPassword. cert and key must be specified together.

Password based authentication:

username - Username for authentication. (Optional)
password - Password for authentication. (Optional)

Credential based authentication:

TLS:

tls - To enable SSL auth for etcd, set this to enable. If not set, TLS for etcd is not used. (Values: enable, disable, Default: disable, Optional)
ca - Certificate authority file for TLS client authentication. (Optional)
cert - Certificate for client authentication. (Optional)
key - Key for client authentication. (Optional)
keyPassword - If set the keyPassword is used to decrypt the provided key. (Optional)

Example

Your etcd cluster no auth:

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: etcd-scaledobject
spec:
  scaleTargetRef:
    name: my-app-target
  pollingInterval: 30
  triggers:
    - type: etcd
      metadata:
        endpoints: 172.0.0.1:2379,172.0.0.2:2379,172.0.0.3:2379
        watchKey: length
        value: '5.5'

Your etcd cluster turn on Password auth:

apiVersion: v1
kind: Secret
metadata:
  name: keda-etcd-secrets
  namespace: default
data:
  etcd-username: <your username>
  etcd-password: <your password>
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-etcd-credential
  namespace: default
spec:
  secretTargetRef:
    - parameter: username
      name: keda-etcd-secrets
      key: etcd-username
    - parameter: password
      name: keda-etcd-secrets
      key: etcd-password
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: etcd-scaledobject
spec:
  scaleTargetRef:
    name: my-app-target
  pollingInterval: 30
  triggers:
    - type: etcd
      metadata:
        endpoints: 172.0.0.1:2379,172.0.0.2:2379,172.0.0.3:2379
        watchKey: length
        value: '5.5'
      authenticationRef:
        name: keda-trigger-auth-etcd-credential

Your etcd cluster turn on SASL/TLS auth:

apiVersion: v1
kind: Secret
metadata:
  name: keda-etcd-secrets
  namespace: default
data:
  tls: ZW5hYmxl
  ca: <your ca>
  cert: <your cert>
  key: <your key>
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-etcd-credential
  namespace: default
spec:
  secretTargetRef:
    - parameter: tls
      name: keda-etcd-secrets
      key: tls
    - parameter: ca
      name: keda-etcd-secrets
      key: ca
    - parameter: cert
      name: keda-etcd-secrets
      key: cert
    - parameter: key
      name: keda-etcd-secrets
      key: key
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: etcd-scaledobject
spec:
  scaleTargetRef:
    name: my-app-target
  pollingInterval: 30
  triggers:
    - type: etcd
      metadata:
        endpoints: 172.0.0.1:2379,172.0.0.2:2379,172.0.0.3:2379
        watchKey: length
        value: '5.5'
      authenticationRef:
        name: keda-trigger-auth-etcd-credential