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wasmcloud-operator

An operator for managing a set of wasmCloud hosts running on Kubernetes and manage wasmCloud applications using wadm. The goal is to easily be able to run WasmCloud hosts on a Kubernetes cluster.

WasmCloudHostConfig Custom Resource Definition (CRD)

The WasmCloudHostConfig CRD describes the desired state of a set of wasmCloud hosts connected to the same lattice.

apiVersion: k8s.wasmcloud.dev/v1alpha1
kind: WasmCloudHostConfig
metadata:
  name: my-wasmcloud-cluster
spec:
  # The number of wasmCloud host pods to run
  hostReplicas: 2
  # The lattice to connect the hosts to
  lattice: default
  # Additional labels to apply to the host other than the defaults set in the operator
  hostLabels:
    some-label: value
  # The address to connect to nats
  natsAddress: nats://nats.default.svc.cluster.local
  # Which wasmCloud version to use
  version: 1.0.4
  # Enable the following to run the wasmCloud hosts as a DaemonSet
  #daemonset: true
  # The name of the image pull secret to use with wasmCloud hosts so that they
  # can authenticate to a private registry to pull components.
  # registryCredentialsSecret: my-registry-secret

The CRD requires a Kubernetes Secret with the following keys:

apiVersion: v1
kind: Secret
metadata:
  name: my-wasmcloud-cluster
#data:
# Only required if using a NATS creds file
# nats.creds: <creds file>

The operator will fail to provision the wasmCloud Deployment if any of these secrets are missing!

Customizing the images used for wasmCloud host and NATS leaf

If you would like to customize the registry or image that gets used to provision the wasmCloud hosts and the NATS leaf that runs alongside them, you can specify the following options in the above WasmCloudHostConfig CRD.

For wasmCloud Host, use the image field:

apiVersion: k8s.wasmcloud.dev/v1alpha1
kind: WasmCloudHostConfig
metadata:
  name: my-wasmcloud-cluster
spec:
  # other config options omitted
  image: registry.example.com/wasmcloud:1.0.2

For the NATS leaf, use the natsImageLeaf field:

apiVersion: k8s.wasmcloud.dev/v1alpha1
kind: WasmCloudHostConfig
metadata:
  name: my-wasmcloud-cluster
spec:
  # other config options omitted
  natsLeafImage: registry.example.com/nats:2.10.16

Image Pull Secrets

You can also specify an image pull secret to use use with the wasmCloud hosts so that they can pull components from a private registry. This secret needs to be in the same namespace as the WasmCloudHostConfig CRD and must be a kubernetes.io/dockerconfigjson type secret. See the Kubernetes documentation for more information on how to provision that secret.

Once it is created, you can reference it in the WasmCloudHostConfig CRD by setting the registryCredentialsSecret field to the name of the secret.

Deploying the operator

A wasmCloud cluster requires a few things to run:

  • A NATS cluster with Jetstream enabled
  • WADM connected to the NATS cluster in order to support applications

If you are running locally, you can use the following commands to start a NATS cluster and WADM in your Kubernetes cluster.

Running NATS

Use the upstream NATS Helm chart to start a cluster with the following values.yaml file:

config:
  cluster:
    enabled: true
    replicas: 3
  leafnodes:
    enabled: true
  jetstream:
    enabled: true
    fileStore:
      pvc:
        size: 10Gi
    merge:
      domain: default
helm repo add nats https://nats-io.github.io/k8s/helm/charts/
helm upgrade --install -f values.yaml nats nats/nats

Running Wadm

You can run Wadm in your Kubernetes cluster using our Helm chart. For a minimal deployment using the NATS server deployed above, all you need in your values.yaml file is:

wadm:
  config:
    nats:
      server: "nats.default.svc.cluster.local:4222"

You can deploy Wadm using your values file and Helm:

helm install wadm -f wadm-values.yaml --version 0.2.0 oci://ghcr.io/wasmcloud/charts/wadm

Start the operator

kubectl kustomize deploy/base | kubectl apply -f -

Automatically Syncing Kubernetes Services

The operator automatically creates Kubernetes Services for wasmCloud applications. Right now this is limited only to applications that deploy the wasmCloud httpserver component using a daemonscaler, but additional support for spreadscalers will be added in the future.

If you specify host label selectors on the daemonscaler then the operator will honor those labels and will only create a service for the pods that match those label selectors.

Argo CD Health Check

Argo CD provides a way to define a custom health check that it then runs against a given resource to determine whether or not the resource is in healthy state.

For this purpose, we specifically expose a status.phase field, which exposes the underlying status information from wadm.

With the following ConfigMap, a custom health check can be added to an existing Argo CD installation for tracking the health of wadm applications.

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-cm
  namespace: argocd
  labels:
    app.kubernetes.io/name: argocd-cm
    app.kubernetes.io/part-of: argocd
data:
  resource.customizations: |
    core.oam.dev/Application:
      health.lua: |
        hs = {}
        hs.status = "Progressing"
        hs.message = "Reconciling application state"
        if obj.status ~= nil and obj.status.phase ~= nil then
          if obj.status.phase == "Deployed" then
            hs.status = "Healthy"
            hs.message = "Application is ready"
          end
          if obj.status.phase == "Reconciling" then
            hs.status = "Progressing"
            hs.message = "Application has been deployed"
          end
          if obj.status.phase == "Failed" then
            hs.status = "Degraded"
            hs.message = "Application failed to deploy"
          end
          if obj.status.phase == "Undeployed" then
            hs.status = "Suspended"
            hs.message = "Application is undeployed"
          end
        end
        return hs

Testing

  • Make sure you have a Kubernetes cluster running locally. Some good options include Kind or Docker Desktop.
  • RUST_LOG=info cargo run

Types crate

This repo stores the types for any CRDs used by the operator in a separate crate (wasmcloud-operator-types) so that they can be reused in other projects.