Loki | KEDA

Scale applications based on Loki query result.

Availability: v2.9+ Maintainer: Community

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Trigger Specification

This specification describes the loki trigger that scales based on a Loki query result. Here is an example of providing values in metadata:

triggers:
- type: loki
  metadata:
    # Required fields:
    serverAddress: http://<loki-host>:3100 # Note: loki server URL 
    query: sum(rate({filename="/var/log/syslog"}[1m])) # Note: query must return a vector/scalar single element response
    threshold: '0.7'
    # Optional fields:
    activationThreshold: '2.50'
    tenantName: Tenant1 # Optional. X-Scope-OrgID header for specifying the tenant name in a multi-tenant setup.
    ignoreNullValues: false # Default is `true`, which means ignoring the empty value list from Loki. Set to `false` the scaler will return error when Loki target is lost
    unsafeSsl: "false" #  Default is `false`, Used for skipping certificate check when having self-signed certs for Loki endpoint

Parameter list:

serverAddress - URL of Loki server.
query - LogQL query to run. The query must return a vector/scalar single element response.
threshold - Value to start scaling for. (This value can be a float)
activationThreshold - Target value for activating the scaler. Learn more about activation here.(Default: 0, Optional, This value can be a float)
tenantName - The X-Scope-OrgID header for specifying the tenant name in a multi-tenant setup. (Optional)
ignoreNullValues - Value to reporting error when Loki target is lost. (Values: true,false, Default: true, Optional)
unsafeSsl - Used for skipping certificate check e.g: using self-signed certs. (Values: true,false, Default: false, Optional)
authModes - Authentaication mode to be used. (Values: bearer,basic, Optional)

Authentication Parameters

Loki doesn’t provide any kind of authentication out of the box. However, most commonly Loki is configured along with a Basic Auth or Bearer Auth, which are the only valid options for authentication here.

You can use TriggerAuthentication CRD to configure the authentication. 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.

Basic authentication:

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

Example

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: loki-scaledobject
  namespace: default
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: nginx
  triggers:
    - type: loki
      metadata:
        serverAddress: http://<loki-host>:3100
        threshold: '0.7'
        query: sum(rate({filename="/var/log/syslog"}[1m]))

Here is an example of a loki scaler with Bearer Authentication, where the Secret and TriggerAuthentication are defined as follows:

apiVersion: v1
kind: Secret
metadata:
  name: keda-loki-secret
  namespace: default
data:
  bearerToken: "BEARER_TOKEN"
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-loki-creds
  namespace: default
spec:
  secretTargetRef:
    - parameter: bearerToken
      name: keda-loki-secret
      key: bearerToken
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: loki-scaledobject
  namespace: default
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: nginx
  triggers:
    - type: loki
      metadata:
        serverAddress: http://<loki-host>:3100
        threshold: '0.7'
        query: sum(rate({filename="/var/log/syslog"}[1m]))
        authModes: "bearer"
      authenticationRef:
        name: keda-loki-creds

Here is an example of a loki scaler with Basic Authentication, where the Secret and TriggerAuthentication are defined as follows:

apiVersion: v1
kind: Secret
metadata:
  name: keda-loki-secret
  namespace: default
data:
  username: dXNlcm5hbWU=
  password: cGFzc3dvcmQ=
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-loki-creds
  namespace: default
spec:
  secretTargetRef:
    - parameter: username
      name: keda-loki-secret
      key: username
    - parameter: password
      name: keda-loki-secret
      key: password
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: loki-scaledobject
  namespace: default
spec:
  maxReplicaCount: 12
  scaleTargetRef:
    name: nginx
  triggers:
    - type: loki
      metadata:
        serverAddress: http://<loki-host>:3100
        threshold: '0.7'
        query: sum(rate({filename="/var/log/syslog"}[1m]))
        authModes: "basic"
      authenticationRef:
        name: keda-loki-creds