knative-ws-example

Simple Knative example consisting of Web UI which uses WebSockets to display POST'ed Cloud Events.

Prerequisites

Note, this sample requires Knative v0.4 or better

Additionally, if you are want to build the demo you will need gcloud installed. See Installing Google Cloud SDK

Setup

In configuring the The Knative WebSocket example we will deploy pre-built image of this application and use curl to post messages to that application, which if everything is configured correctly, will show on in the UI.

Note, if you prefer to build your own image please see Build section bellow

Token

To prevent just anyone publishing to your application we are going to configure token which will be shared between the application and all permitted clients. Let's start by creating a token

KNOWN_PUBLISHER_TOKEN=$(uuidgen)
echo $KNOWN_PUBLISHER_TOKEN

Namespace

If you don't already have a demo namespace created

kubectl create ns demo

Secret

Before deploying our application we will load the above token into the Knative cluster as a secret so that our application can use it

kubectl create secret generic kws -n demo \
	--from-literal=KNOWN_PUBLISHER_TOKEN=${KNOWN_PUBLISHER_TOKEN}

Service

Once our namespace and secret is created, you can apply the (deployment/service.yaml) to deploy the application

kubectl -n demo apply -f \
    https://raw.githubusercontent.com/mchmarny/knative-ws-example/master/deployment/service.yaml

If everything worked correctly you should be able to see the kws service listed as running

kubectl get pods -n demo

NAME                                      READY     STATUS      RESTARTS   AGE
kws-00001-deployment-74c64b8d6b-6dqds     3/3       Running     1          1m

Demo

UI

First navigate to the newly deployed application

http://kws.demo.YOUR-DOAIN.com/

The status message on the top fo the screen should say Opening Connection

Client

Now that the application is deployed, you can use curl to post to its endpoint and the messages should show on the UI. For ease of demonstration we are going to post a simple text message with hard-coded values.

curl -H "Content-Type: text/plain" \
     -H "ce-specversion: 0.2" \
     -H "ce-type: github.com.mchmarny.knative-ws-example.message" \
     -H "ce-source: https://github.com/mchmarny/knative-ws-example" \
     -H "ce-id: $(uuidgen)" \
     -H "ce-time: $(date +%Y-%m-%dT%H:%M:%S:%Z)" \
     -H "ce-token: $(KNOWN_PUBLISHER_TOKEN)" \
     -X POST --data "My sample message" \
    https://kws.demo.knative.tech/v1/event

Every time you run that command, a new message should be added to the UI. Go ahead, change the data value from This is my sample message to something else and post it.

Build

Note, do this only if you want to build from source, otherwise use the pre-built image

Quickest way to build your service image is through GCP Build. Just submit the build request using the bellow command

gcloud builds submit \
    --project ${YOUR_GCP_PROJECT} \
	--tag gcr.io/${YOUR_GCP_PROJECT}/kws

The build service is pretty verbose in output but eventually you should see something like this

ID           CREATE_TIME          DURATION  SOURCE                                   IMAGES               STATUS
6905dd3a...  2018-12-23T03:48...  1M43S     gs://PROJECT_cloudbuild/source/15...tgz  gcr.io/PROJECT/kws   SUCCESS

Copy the image URI from IMAGE column (e.g. gcr.io/PROJECT/kws).

Configure Knative

Now in the deployment/service.yaml file update the image URI to value of IMAGE column above

Disclaimer

This is my personal project and it does not represent my employer. I take no responsibility for issues caused by this code. I do my best to ensure that everything works, but if something goes wrong, my apologies is all you will get.