Example Rabbit + Knative broker setup

This repo intends to have a minimal set of steps to run in order to create a working example service that retrieves and processes events from knative using a broker that's provided by rabbitmq.

It uses parts of both the knative documentation and the rabbitmq documentation.

A set of steps is layed out that combines the examples to effect a service that listens for knative messages, and a broker used by knative that is based on a rabbitmq instance created as part of the cluster.

Installation

These steps are intended to be as minimal as possible. If you have any trouble with them, please create an issue, or ping me directly.

Presumptions:

It's assumed that you already have a kubernetes cluster that has knative installed. If you do not, and you're doing local development, I'd recommend looking at the kn tool, which will allow you to create a cluster with either kind or minikube, and will automatically install knative for you.

Rabbit Infrastructure:

We'll be installing a certificate manager to handle authentication between rabbitmq and brokers, then a rabbitmq kubernetes operator, and finally checking to see if everything is installed correctly.

The instructions and their yaml files come from the linked repositories.

# https://github.com/rabbitmq/cluster-operator
kubectl apply -f rabbit/cluster-operator.yml
kubectl apply -f rabbit/rabbitmq.yaml

# https://knative.dev/docs/eventing/brokers/broker-types/rabbitmq-broker/
kubectl apply -f rabbit/rabbitmq-cluster-config.yaml
# check for  running "rabbitmq-broker-controller"
kubectl get deployments.apps -n knative-eventing

Basic eventing service using the rabbitmq infrastructure

This is the application that we'll use to handle events on a broker via knative. It will create a broker, and a configuration for that broker that will direct it to use the rabbitmq instance we've created.

Build our event-handling container and load it into our cluster

cd helloworld-go
docker build -t dev.local/kevents:latest .
# The following code uploads the container into a kind cluster.
# Those using minikube will have an equivalent command, but I'm
# unsure of what it is.
kind load docker-image dev.local/kevents:latest --name knative --namespace knative-samples

Spin up our rabbitmq and event-handling k8s infrastructure

# assuming you're still inside the 'helloworld-go' directory 
kubectl apply -f sample-app.yaml trigger.yaml

Test that event handling occurring

# Get our broker URL
kubectl get broker --namespace knative-samples | grep -v NAME | awk '{ printf $2 }'

# Run a curl instance we can use to send a message to the broker
kubectl -n knative-samples run curl --image=radial/busyboxplus:curl -it

# Inside the container we've started, send a message to our rabbit broker
# using curl, and using the broker URL we got in the first command
curl -v "<THE URL FROM THE FIRST COMMAND>" \
-X POST \
-H "Ce-Id: 536808d3-88be-4077-9d7a-a3f162705f79" \
-H "Ce-Specversion: 1.0" \
-H "Ce-Type: dev.knative.samples.helloworld" \
-H "Ce-Source: dev.knative.samples/helloworldsource" \
-H "Content-Type: application/json" \
-d '{"msg":"Hello World from the curl pod."}'

# Leave the container
exit

# Print the logs of the event-handline container to see if it received an event:
kubectl --namespace knative-samples logs -l app=helloworld-go --tail=50

# You should see something similar to:
Event received.
Validation: valid
Context Attributes,
 specversion: 1.0
 type: dev.knative.samples.helloworld
 source: dev.knative.samples/helloworldsource
 id: 536808d3-88be-4077-9d7a-a3f162705f79
 time: 2019-10-04T22:35:26.05871736Z
 datacontenttype: application/json
Extensions,
 knativearrivaltime: 2019-10-04T22:35:26Z
 knativehistory: default-kn2-trigger-kn-channel.knative-samples.svc.cluster.local
 traceparent: 00-971d4644229653483d38c46e92a959c7-92c66312e4bb39be-00
Data,
  {"msg":"Hello World from the curl pod."}

Hello World Message "Hello World from the curl pod."
Responded with event
Validation: valid
Context Attributes,
  specversion: 1.0
  type: dev.knative.samples.hifromknative
  source: knative/eventing/samples/hello-world
  id: 37458d77-01f5-411e-a243-a459bbf79682
  datacontenttype: application/json
Data,
  {"msg":"Hi from Knative!"}

And that should be it! From there, you should be able to create services that hit the endpoint at the URL you hit with CURL, and use the yaml and hellow-world container as a base for services that handle events.