Secrets

Kuma provides a built-in interface to store sensitive information such as TLS keys and tokens that can be used later on by any policy at runtime. This functionality is being implemented by introducing a Secret resource.

Secrets belong to a specific Mesh resource, and cannot be shared across different Meshes.

Kuma will also leverage Secret resources internally for certain operations, for example when storing auto-generated certificates and keys when Mutual TLS is enabled.

On Kubernetes, Kuma under the hood leverages the native Kubernetes Secret (opens new window) resource to store sensitive information.

Kuma secrets are stored in the same namespace as the Control Plane with type valued as system.kuma.io/secret:

apiVersion: v1
kind: Secret
metadata:
  name: sample-secret
  namespace: kuma-system # Kuma will only manage secrets in the same namespace as the CP
  labels:
    kuma.io/mesh: default # specify the Mesh scope of the secret 
data:
  value: dGVzdAo= # bytes encoded in Base64
type: system.kuma.io/secret # Kuma will only manage secrets of this type

Use kubectl to manage secrets like any other Kubernetes resource.

echo "apiVersion: v1
kind: Secret
metadata:
  name: sample-secret
  namespace: kuma-system
  labels:
    kuma.io/mesh: default 
data:
  value: dGVzdAo=
type: system.kuma.io/secret" | kubectl apply -f -

kubectl get secrets -n kuma-system --field-selector='type=system.kuma.io/secret'
# NAME            TYPE                    DATA   AGE
# sample-secret   system.kuma.io/secret   1      3m12s

Kubernetes Secrets are identified with the name + namespace format, therefore it is not possible to have a Secret with the same name in multiple meshes (since multiple Meshes always belong to one Kuma CP that always runs in one Namespace).

In order to reassign a Secret to another Mesh you need to delete the Secret resource and apply it again.

A Secret is a simple resource that stores specific data:

type: Secret
name: sample-secret
mesh: default
data: dGVzdAo= # bytes encoded in Base64

You can use kumactl to manage any Secret like you would do for other resources:

echo "type: Secret
mesh: default
name: sample-secret
data: dGVzdAo=" | kumactl apply -f -

The data field of a Kuma Secret should always be a Base64 encoded value. You can use the base64 command in Linux or macOS to encode any value in Base64:

# Base64 encode a file
cat cert.pem | base64

# or Base64 encode a string
echo "value" | base64

Access to the Secret HTTP API

This API requires authentication. Consult Accessing Admin Server from a different machine how to configure remote access.

Scope of the Secret

Kuma provides two types of Secrets.

Mesh-scoped Secrets

Mesh-scoped Secrets are bound to a given Mesh. Only this kind of Secrets can be used in Mesh Policies like Provided CA or TLS setting in External Service.

apiVersion: v1
kind: Secret
metadata:
  name: sample-secret
  namespace: kuma-system
  labels:
    kuma.io/mesh: default # specify the Mesh scope of the secret 
data:
  value: dGVzdAo=
type: system.kuma.io/secret

type: Secret
name: sample-secret
mesh: default # specify the Mesh scope of the secret
data: dGVzdAo=

Global-scoped Secrets

Global-scoped Secrets are not bound to a given Mesh and cannot be used in Mesh Policies. They are used for internal purposes. You can manage them just like the regular secrets using kumactl or kubectl.

Notice that the type is different and kuma.io/mesh label is not present.

apiVersion: v1
kind: Secret
metadata:
  name: sample-secret
  namespace: kuma-system 
data:
  value: dGVzdAo=
type: system.kuma.io/global-secret

Notice that the type is different and mesh field is not present.

type: GlobalSecret
name: sample-global-secret
data: dGVzdAo=

Usage

Here is example of how you can use a Kuma Secret with a provided Mutual TLS backend.

The examples below assume that the Secret object has already been created before-hand.

type: Mesh
name: default
mtls:
  backends:
  - name: ca-1
    type: provided
    config:
      cert:
        secret: my-cert # name of the Kuma Secret
      key:
        secret: my-key # name of the Kuma Secret

apiVersion: kuma.io/v1alpha1
kind: Mesh
metadata:
  name: default
spec:
  mtls:
    backends:
    - name: ca-1
      type: provided
      config:
        cert:
          secret: my-cert # name of the Kubernetes Secret
        key:
          secret: my-key # name of the Kubernetes Secret