Often a scaler will require authentication or secrets and config to check for events.

KEDA provides a few secure patterns to manage authentication flows:

• Configure authentication per ScaledObject
• Re-use per-namespace credentials or delegate authentication with TriggerAuthentication
• Re-use global credentials with ClusterTriggerAuthentication

Defining secrets and config maps on ScaledObject

Some metadata parameters will not allow resolving from a literal value, and will instead require a reference to a secret, config map, or environment variable defined on the target container.

💡 TIP: If creating a deployment yaml that references a secret, be sure the secret is created before the deployment that references it, and the scaledObject after both of them to avoid invalid references.

Example

If using the RabbitMQ scaler, the host parameter may include passwords so is required to be a reference. You can create a secret with the value of the host string, reference that secret in the deployment, and map it to the ScaledObject metadata parameter like below:

apiVersion: v1
kind: Secret
metadata:
  name: {secret-name}
data:
  {secret-key-name}: YW1xcDovL3VzZXI6UEFTU1dPUkRAcmFiYml0bXEuZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbDo1Njcy #base64 encoded per secret spec
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {deployment-name}
  namespace: default
  labels:
    app: {deployment-name}
spec:
  selector:
    matchLabels:
      app: {deployment-name}
  template:
    metadata:
      labels:
        app: {deployment-name}
    spec:
      containers:
      - name: {deployment-name}
        image: {container-image}
        envFrom:
        - secretRef:
            name: {secret-name}
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: {scaled-object-name}
  namespace: default
spec:
  scaleTargetRef:
    name: {deployment-name}
  triggers:
  - type: rabbitmq
    metadata:
      queueName: hello
      host: {secret-key-name}
      queueLength  : '5'

If you have multiple containers in a deployment, you will need to include the name of the container that has the references in the ScaledObject. If you do not include a envSourceContainerName it will default to the first container. KEDA will attempt to resolve references from secrets, config maps, and environment variables of the container.

The downsides

While this method works for many scenarios, there are some downsides:

• Difficult to efficiently share auth config across ScaledObjects
• No support for referencing a secret directly, only secrets that are referenced by the container
• No support for other types of authentication flows such as pod identity where access to a source could be acquired with no secrets or connection strings

For these and other reasons, we also provide a TriggerAuthentication resource to define authentication as a separate resource to a ScaledObject. This allows you to reference secrets directly, configure to use pod identity or use authentication object managed by a different team.

Re-use credentials and delegate auth with TriggerAuthentication

TriggerAuthentication allows you to describe authentication parameters separate from the ScaledObject and the deployment containers. It also enables more advanced methods of authentication like “pod identity”, authentication re-use or allowing IT to configure the authentication.

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: {trigger-authentication-name}
  namespace: default # must be same namespace as the ScaledObject
spec:
  podIdentity:
      provider: none | azure | aws-eks | aws-kiam  # Optional. Default: none
  secretTargetRef:                                    # Optional.
  - parameter: {scaledObject-parameter-name}          # Required.
    name: {secret-name}                               # Required.
    key: {secret-key-name}                            # Required.
  env:                                                # Optional.
  - parameter: {scaledObject-parameter-name}          # Required.
    name: {env-name}                                  # Required.
    containerName: {container-name}                   # Optional. Default: scaleTargetRef.envSourceContainerName of ScaledObject
  hashiCorpVault:                                     # Optional.
    address: {hashicorp-vault-address}                # Required.
    authentication: token | kubernetes                # Required.
    role: {hashicorp-vault-role}                      # Optional.
    mount: {hashicorp-vault-mount}                    # Optional.
    credential:                                       # Optional.
      token: {hashicorp-vault-token}                  # Optional.
      serviceAccount: {path-to-service-account-file}  # Optional.
    secrets:                                          # Required.
    - parameter: {scaledObject-parameter-name}        # Required.
      key: {hashicorp-vault-secret-key-name}           # Required.
      path: {hashicorp-vault-secret-path}              # Required.

Based on the requirements you can mix and match the reference types providers in order to configure all required parameters.

Every parameter you define in TriggerAuthentication definition does not need to be included in the metadata of the trigger for your ScaledObject definition. To reference a TriggerAuthentication from a ScaledObject you add the authenticationRef to the trigger.

# some Scaled Object
# ...
  triggers:
  - type: {scaler-type}
    metadata:
      param1: {some-value}
    authenticationRef:
      name: {trigger-authentication-name} # this may define other params not defined in metadata

Authentication scopes: Namespace vs. Cluster

Each TriggerAuthentication is defined in one namespace and can only be used by a ScaledObject in that same namespace. For cases where you want to share a single set of credentials between scalers in many namespaces, you can instead create a ClusterTriggerAuthentication. As a global object, this can be used from any namespace. To set a trigger to use a ClusterTriggerAuthentication, add a kind field to the authentication reference:

    authenticationRef:
      name: {cluster-trigger-authentication-name}
      kind: ClusterTriggerAuthentication

By default, Secrets loaded from a secretTargetRef must be in the same namespace as KEDA is deployed in (usually keda). This can be overridden by setting a KEDA_CLUSTER_OBJECT_NAMESPACE environment variable for the keda-operator container.

Defining a ClusterTriggerAuthentication works almost identically to a TriggerAuthentication, except there is no metadata.namespace value:

apiVersion: keda.sh/v1alpha1
kind: ClusterTriggerAuthentication
metadata:
  name: {cluster-trigger-authentication-name}
spec:
  # As before ...

Available authentication providers for KEDA

Authentication parameters can be retrieved from a variety of authentication providers in KEDA: