Secrets

The Secret resource enables users to store sensitive data. Sensitive information is anything a user considers non-public, e.g.:

  • TLS keys
  • tokens
  • passwords

Secrets belong to a specific Mesh resource, and cannot be shared across different Meshes. Policies use secrets at runtime.

Kuma leverages 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 resource to store sensitive information.

Kuma secrets are stored in the same namespace as the Control Plane with type set to 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= # Base64 encoded
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. Multiple Meshes always belong to one Kuma CP that always runs in one Namespace.

In order to reassign a Secret from one Mesh to another Mesh you need to delete the Secret resource and create it in another Mesh.

The data field of a Kuma Secret is a Base64 encoded value. 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

Secret API requires authentication. Consult Accessing Admin Server from a different machine for 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

Global-scoped Secrets

Global-scoped Secrets are not bound to a given Mesh and cannot be used in Mesh Policies. Global-scoped Secrets 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

Usage

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

The examples below assumes that the Secret object has already been created beforehand.

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
Last Updated: 11/4/2022, 19:20:08 PM