VMware Event Broker on Kubernetes with Knative functions - part 2

VMware Event Broker on Kubernetes with Knative functions - part 2


This post is the second part of a small series about VMware Event Broker on Kubernetes with Knative functions.

If you plan to apply the following procedure, we assume that the content mentioned in the Part 1 is already deployed in your target setup.

Deploy VMware Event Broker with knative support

Disclaimer: This section of the post was made with the help of @embano1 who provided a knative-ready helm chart for vcenter-event-broker deployment (PR:392). He also provided an example of the override.yaml file we will use below.

Create a namespace

The following commands will create a namespace vmware-fn to host and run automation functions.

 1cat << EOF > vmware-fn-ns.yaml
 3apiVersion: v1
 4kind: Namespace
 6  name: vmware-fn
 9kubectl apply -f vmware-fn-ns.yaml
11kubectl get ns vmware-fn
12# Output
13NAME        STATUS   AGE
14vmware-fn   Active   10s

Of course: you can customize this target namespace and even re-use an existing one.

Create a Broker

 1cat << EOF > mt-broker.yaml
 3apiVersion: eventing.knative.dev/v1
 4kind: Broker
 6  name: vmware-event-broker
 7  namespace: vmware-fn
10kubectl apply -f mt-broker.yaml
12kubectl get broker -n vmware-fn
13# Output (I remove a loooong URL field)
14NAME                 AGE    READY
15vmware-event-broker  23s    True

Prepare event-router configuration

Create an override.yaml with your settings:

 1cat << EOF > override.yaml
 3  config:
 4    logLevel: debug
 5  vcenter:
 6    address: https://vcsa.local
 7    username: test@vsphere.local
 8    password: VMware1!
 9    insecure: true # ignore TLS certs if required
10  eventProcessor: knative  
11  knative:
12    destination:
13      ref:
14        apiVersion: eventing.knative.dev/v1
15        kind: Broker # we use a Knative broker to send events to
16        name: vmware-event-broker # name of the broker
17        namespace: vmware-fn # namespace where the broker is deployed

Ensure to specify broker name and namespace according to the one configured in the previous section.

Helm deployment

If not already done, we will register the veba helm-charts registry and get metadata locally:

1# register chart repo and update chart information
2helm repo add vmware-veba https://projects.registry.vmware.com/chartrepo/veba
3helm repo update

At this time, the support of knative with helm vmware event router deployment method is only supported in chart version >= v0.6.2. Ensure that this version is available:

1helm search repo event-router --versions | grep v0.6.2
2# Output
3vmware-veba/event-router        v0.6.2          v0.6.0          The VMware Event Router is used to connect to v...

Lets deploy it.

Here we create a specific namespace vmware for this purpose but you can reuse vmware-fn or any other one.

1helm install -n vmware --create-namespace veba-knative vmware-veba/event-router -f override.yaml --wait --version v0.6.2
2# Output
3NAME: veba-knative
4LAST DEPLOYED: Wed May  5 12:55:39 2021
5NAMESPACE: vmware
6STATUS: deployed

We can now check that the deployment status:

1helm list --namespace vmware
2# Output
3NAME            NAMESPACE    REVISION    STATUS      CHART                   APP VERSION
4veba-knative    vmware       1           deployed    event-router-v0.6.2     v0.6.0
6kubectl get pod -n vmware
7# Output
8NAME                     READY   STATUS    RESTARTS   AGE
9router-cdc874b59-vpckd   1/1     Running   0          36s


Now its time to perform some tasks based on event routing setup.

Deploy a sample echo function

The first (and very useful!) thing we can do, is to echo cloud events occurring in the target vCenter server.

VEBA team provide multiple echo samples (python or powershell based). Here we will use the python-based one provided by @embano1/kn-echo:

 1cat << EOF > kn-py-echo.yaml
 3apiVersion: serving.knative.dev/v1
 4kind: Service
 6  name: kn-py-echo-svc
 8  template:
 9    metadata:
10      annotations:
11        autoscaling.knative.dev/maxScale: "1"
12        autoscaling.knative.dev/minScale: "0"
13    spec:
14      containers:
15      - image: embano1/kn-echo
17apiVersion: eventing.knative.dev/v1
18kind: Trigger
20  name: kn-py-echo-trigger
22  broker: vmware-event-broker
23  subscriber:
24    ref:
25      apiVersion: serving.knative.dev/v1
26      kind: Service
27      name: kn-py-echo-svc
30kubectl apply -n vmware-fn -f kn-py-echo.yaml
31# Output
32service.serving.knative.dev/kn-py-echo-svc created
33trigger.eventing.knative.dev/kn-py-echo-trigger created

We can check what was created:

 1kn service list -n vmware-fn
 2# Output
 3NAME           URL                                         LATEST               AGE     CONDITIONS   READY   REASON
 4kn-py-echo-svc http://kn-py-echo-svc.vmware-fn.example.com kn-py-echo-svc-00001 3m34s   3 OK / 3     True
 6kn trigger list -n vmware-fn
 7# Output
 8NAME                BROKER                SINK                  AGE    CONDITIONS   READY   REASON
 9kn-py-echo-trigger  vmware-event-broker   ksvc:kn-py-echo-svc   2m8s   5 OK / 5     True
11kubectl get pod -n vmware-fn
12# Output
13NAME                                              READY   STATUS    RESTARTS   AGE
14kn-py-echo-svc-00001-deployment-7d8fcf598-5g8f7   2/2     Running   0          63s

As we specified autoscaling.knative.dev/minScale: "0" in the service definition, the deployed pods may or may not be deployed at a specific time: if there is no event fired by vCenter for a period of time, Knative Serving will terminate the pod associated to the service, and recreate it when new event will arrive:

1kubectl get pod -n vmware-fn
2# Output
3NAME                                              READY   STATUS        RESTARTS   AGE
4No resources found in vmware-fn namespace.

If you want to look at incoming events, get the current running pod name and look at its logs:

1kubectl logs -n vmware-fn kn-py-echo-svc-00001-deployment-7d8fcf598-ngtdd user-container -f

Deploy vm-creation-attr function

I also did a re-write of the vm-creation-attr function I did write for OpenFaaS process to be knative compliant.

As a reminder, I did a(nother long) post a few month back about this function. The main goal is to populate custom attributes values for VM object based on the user who created the VM, the creation date and the last-poweredon date.

The knative function is hosted on GitHub: lrivallain/kn-vm-creation-attr-fn. You can get the function.yaml file to start the deployment:

1curl -LO https://raw.githubusercontent.com/lrivallain/kn-vm-creation-attr-fn/main/function.yaml


Edit the content of function.yaml to configure the following settings:

 1# In `ConfigMap` section
 2VC_SERVER: vcsa.local
 3VC_USER: test@vsphere.local
 5VC_ATTR_OWNER: event-owner
 6VC_ATTR_CREATION_DATE: event-creation_date
 7VC_ATTR_LAST_POWEREDON: event-last_poweredon
 9# In `Secret` section

The VC_PASSWORD is base64 encoded: you can generate it by using a command like:

1echo -n "YourP@ssw0rd" | base64

We assume that you use the previously mentioned vmware-event-broker broker name, but you can change it by using:

1sed -i s/vmware-event-broker/NAMEOFYOURBROKER/ function.yaml


1kubectl appy -n vmware-fn -f function.yaml

Then you can check the result with following commands:

1kn service list -n vmware-fn
3kn trigger list -n vmware-fn
5kubectl get pod -n vmware-fn

You will notice that there is multiple kn-vm-creation-attr-fn-trigger-xxxx triggers deployed. It is due to the filtering applied to incoming event, to only get the one matching some specific actions results.


By looking at pod logs, you can see the actions resulting from the incoming events:

 1172.17.0.1 - - [04/May/2021 14:08:00] "POST / HTTP/1.1" 204 -
 22021-05-04 14:08:00,230 INFO werkzeug Thread-3 : - - [04/May/2021 14:08:00] "POST / HTTP/1.1" 204 -
 32021-05-04 14:09:18,462 DEBUG handler Thread-4 : "***cloud event*** {"attributes": {"specversion": "1.0", "id": "42516969-218a-406f-9ccc-db387befc4bf", 
 4"source": "https://vcsa.local/sdk", "type": "com.vmware.event.router/event", "datacontenttype": "application/json", "subject": "DrsVmPoweredOnEvent", "time": "2021-05-04T07:33:33.773581268Z", "knativearrivaltime": "2021-05-04T07:33:33.772937393Z"}, "data": {"Key": 992270, "ChainId": 992267, "CreatedTime": "2021-05-04T07:33:32.759Z", "UserName": "VSPHERE.LOCAL\\test-user", "Datacenter": {"Name": "Datacenter", "Datacenter": {"Type": "Datacenter", "Value": "datacenter-21"}}, "ComputeResource": {"Name": "Cluster01", "ComputeResource": {"Type": "ClusterComputeResource", "Value": "domain-c84"}}, "Host": {"Name": "esxi1.local", "Host": {"Type": "HostSystem", "Value": "host-34"}}, "Vm": {"Name": "TestVM", "Vm": {"Type": "VirtualMachine", "Value": "vm-596"}}, "Ds": null, "Net": null, "Dvs": null, "FullFormattedMessage": "DRS powered On TestVM on esxi1.local in Datacenter", "ChangeTag": "", "Template": false}
 62021-05-04 14:09:18,464 DEBUG vcenter Thread-4 : Initializing vCenter connection...
 72021-05-04 14:09:18,992 INFO vcenter Thread-4 : Connected to vCenter
 82021-05-04 14:09:19,483 INFO handler Thread-4 : Apply attribute > event-last_poweredon
 92021-05-04 14:09:19,774 DEBUG handler Thread-4 : End of event
10172.17.0.1 - - [04/May/2021 14:09:19] "POST / HTTP/1.1" 204 -
112021-05-04 14:09:19,777 INFO werkzeug Thread-4 : - - [04/May/2021 14:09:19] "POST / HTTP/1.1" 204 -

Is it serverless?

With a autoscaling.knative.dev/minScale: "0" annotation setting (as provided by default in the above functions), have look at the pods list to see the result of an event:

 1k get pods --watch -n vmware-fn
 2# Output
 3kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   0/2     Pending             0          0s
 4kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   0/2     ContainerCreating   0          1s
 5kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   1/2     Running             0          5s
 6kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   1/2     Running             0          6s
 7kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   2/2     Running             0          7s
 8# And after about 60s without events:
 9kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   2/2     Terminating         0          68s
10kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   1/2     Terminating         0          71s
11kn-vm-creation-attr-fn-service-00002-deployment-848865fdd-xgvb9   0/2     Terminating         0          2m8s

As you can see, the function is acting as a serverless one: when needed, the appropriate number of pods is spawned, and when there is not incoming (and matching) event: no pods are kept on the cluster.

You can easily change values of autoscaling.knative.dev/maxScale: "1" and autoscaling.knative.dev/minScale: "0" according to your needs: for example, with minScale: "1": at least one pod will always remain listening for events: This could improve the time to execute an action it there is no pod to spawn after an inactivity period.

So, considering that the service provider is knative, our functions are acting like serverless ones and the management component is in charge of scaling (up and down to 0), the components running our application code, according to the incoming requests: This enable all the benefits of serverless applications and of-course, its drawbacks.


Title photo by James Harrison on Unsplash

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