Eno

Compose Kubernetes deployments.

• 🎹 Synthesize: generate manifests dynamically in short-lived pods
• ♻️ Reconcile: apply the generated configurations and rapidly correct any drift
• 🏃‍➡️ React: re-synthesize when input resources are modified

Docs

• Synthesis
• Reconciliation
• Symphony
• Synthesizer API
• Generated API Docs

Getting Started

1. Install Eno

export TAG=$(curl https://api.github.com/repos/Azure/eno/releases | jq -r '.[0].name')
kubectl apply -f "https://github.com/Azure/eno/releases/download/${TAG}/manifest.yaml"

2. Create a Synthesizer

Synthesizers model a reusable set of resources, similar to an apt package or Helm chart.

⚠️ This example uses a simple bash script but real applications should use Helm, Go, or KCL (currently beta-ish) or any other process that implements the KRM function API.

kubectl apply -f - <<YAML
apiVersion: eno.azure.io/v1
kind: Synthesizer
metadata:
  name: getting-started
  namespace: default
spec:
  # Refs are like arguments.
  # They specify the type of an input required by the
  # synthesizer without "binding" to a particular resource.
  refs:
    - key: config
      resource:
        group: "" # core
        version: v1
        kind: ConfigMap

  # Synthesizers are simple containers distributed
  # as OCI images and executed in short-lived pods
  image: docker.io/ubuntu:latest
  command:
  - /bin/bash
  - -c
  - |
      # Read inputs from stdin
      replica_count=\$(sed -n 's/.*"replicas":"\([^"]*\)".*/\1/p')

      # Write the resulting KRM resource list to stdout
      echo '{
        "apiVersion":"config.kubernetes.io/v1",
        "kind":"ResourceList",
        "items":[
          {
            "apiVersion":"apps/v1",
            "kind":"Deployment",
            "metadata":{
              "name":"my-app",
              "namespace": "default"
            },
            "spec": {
              "replicas": REPLICA_COUNT,
              "selector": { "matchLabels": { "app": "getting-started" } },
              "template": {
                "metadata": { "labels": { "app": "getting-started" } },
                "spec": {
                  "containers": [{ "name": "svc", "image": "nginx" }]
                }
              }
            }
          }
        ]
      }' | sed "s/REPLICA_COUNT/\$replica_count/g"
YAML

3. Create a Composition

Compositions instantiate Synthesizers, similar to installing a package or creating a Helm release.

kubectl apply -f - <<YAML
  apiVersion: eno.azure.io/v1
  kind: Composition
  metadata:
    name: my-first-composition
    namespace: default
  spec:
    synthesizer:
      name: getting-started # references the name of the Synthesizer object

    # Bindings assign a specific object to refs exposed by the Synthesizer.
    # Many compositions can use the one synthesizer while passing unique inputs.
    bindings:
      - key: config
        resource:
          name: my-first-config
          namespace: default

---

  apiVersion: v1
  kind: ConfigMap
  metadata:
    name: my-first-config
    namespace: default
  data:
    replicas: "1"
YAML

Eno will execute the synthesizer in a short-lived pod and create the resulting resource(s).

$ kubectl get composition
NAME                   SYNTHESIZER       AGE   STATUS   ERROR
my-first-composition   getting-started   0s    Ready

$ kubectl get deploy my-app
NAME     READY   UP-TO-DATE   AVAILABLE   AGE
my-app   1/1     1            1           0s

4. Resynthesize

Eno will automatically "resynthesize" the composition when its inputs change.

kubectl patch configmap my-first-config --patch '{"data":{"replicas":"2"}}'

$ kubectl get deploy my-app
NAME     READY   UP-TO-DATE   AVAILABLE   AGE
my-app   2/2     2            2           2m

Contributing

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This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Trademarks

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