OAM Kubernetes Runtime

The official Kubernetes plug-in for Open Application Model (OAM).

OAM Kubernetes Runtime implements OAM specification to expose application centric API for any Kubernetes, specifically:

Components - what workload to run?
Traits - how to operate the workload?
ApplicationConfiguration - apply traits to component
Definitions - discover CRD/k8s API resource as workload/trait

This plug-in is designed as building block for creating OAM compliant platform with Kubernetes, rather than being used directly by developers or end-users.

Architecture

Prerequisites

Kubernetes v1.16+
Helm 3

Install OAM Kubernetes Runtime

Create namespace for OAM runtime controller

kubectl create namespace oam-system

Add helm repo

helm repo add crossplane-master https://charts.crossplane.io/master/

Install OAM Kubernetes Runtime

You can directly install it without webhook by:

helm install oam --namespace oam-system crossplane-master/oam-kubernetes-runtime --devel

Or you can install with webhook enabled by following steps:

Step 1: Admission Webhook need you to prepare certificates and ca for production use. For none-production use, you could generate them by running the shell script provided in repo.

curl -sfL https://raw.githubusercontent.com/crossplane/oam-kubernetes-runtime/master/hack/ssl/ssl.sh | bash -s oam-kubernetes-runtime-webhook oam-system

The shell will generate files like below:

$ tree
.
├── csr.conf
├── oam-kubernetes-runtime-webhook.csr
├── oam-kubernetes-runtime-webhook.key
└── oam-kubernetes-runtime-webhook.pem

0 directories, 4 files

Step 2: Create secret for ssl certificates:
- Notice the server key and certificate must be named tls.key and tls.crt, respectively.
- Secret name can be user defined, we'd better align with chart values.
```
kubectl -n oam-system create secret generic webhook-server-cert --from-file=tls.key=./oam-kubernetes-runtime-webhook.key --from-file=tls.crt=./oam-kubernetes-runtime-webhook.pem
```

Step 3: Get CA Bundle info and install with it's value

caValue=`kubectl config view --raw --minify --flatten -o jsonpath='{.clusters[].cluster.certificate-authority-data}'`
helm install core-runtime -n oam-system ./charts/oam-kubernetes-runtime --set useWebhook=true --set certificate.caBundle=$caValue

Get started

We have some examples in our repo, clone and get started with it.

git clone git@github.com:crossplane/oam-kubernetes-runtime.git	
cd ./oam-kubernetes-runtime

Apply a sample application configuration

kubectl apply -f examples/containerized-workload

Verify that the application is running

Check its components:

kubectl get components
NAME                WORKLOAD-KIND           AGE
example-component   ContainerizedWorkload   63s

Check its application configuration:

kubectl get appconfigs
NAME                AGE
example-appconfig   3m48s

Check the status and events from the application

kubectl describe appconfig example-appconfig
Status:
  Conditions:
    Last Transition Time:  2020-06-12T21:18:40Z
    Reason:                Successfully reconciled resource
    Status:                True
    Type:                  Synced
  Workloads:
    Component Name:  example-component
    Traits:
      Trait Ref:
        API Version:  core.oam.dev/v1alpha2
        Kind:         ManualScalerTrait
        Name:         example-appconfig-trait
    Workload Ref:
      API Version:  core.oam.dev/v1alpha2
      Kind:         ContainerizedWorkload
      Name:         example-appconfig-workload
Events:
  Type    Reason                 Age              From                                       Message
  ----    ------                 ----             ----                                       -------
  Normal  RenderedComponents     6s (x2 over 7s)  oam/applicationconfiguration.core.oam.dev  Successfully rendered components
  Normal  AppliedComponents      6s (x2 over 6s)  oam/applicationconfiguration.core.oam.dev  Successfully applied components
  Normal  Deployment created     6s (x3 over 6s)  ContainerizedWorkload                      Workload `example-appconfig-workload` successfully server side patched a deployment `example-appconfig-workload`
  Normal  Service created        6s (x3 over 6s)  ContainerizedWorkload                      Workload `example-appconfig-workload` successfully server side patched a service `example-appconfig-workload`
  Normal  Manual scalar applied  6s (x2 over 6s)  ManualScalarTrait                          Trait `example-appconfig-trait` successfully scaled a resouce to 3 instances

You should also check underlying deployment and service looking like below

kubectl get deployments
NAME                                    READY   UP-TO-DATE   AVAILABLE   AGE
example-appconfig-workload-deployment   3/3   3           3              28s

kubectl get services
AME                                             TYPE       CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
example-appconfig-workload-deployment-service   NodePort   10.96.78.215   <none>        8080/TCP   28s

Cleanup

helm uninstall core-runtime -n oam-system
kubectl delete -f examples/containerized-workload
kubectl delete namespace oam-system --wait

Community, discussion, contribution

You can reach the maintainers of this project at:

Slack channel: crossplane#oam

Want to help?

Check out DEVELOPMENT.md to see how to develop with OAM Kubernetes runtime

Licenses

The OAM Kubernetes runtime is released under the Apache 2.0 license.

kumarh1982/oam-kubernetes-runtime