sink

Redis Stream Sink

The Redis Stream Event Sink for Knative receives CloudEvents and adds them to the specified stream of the Redis instance.

The Redis Stream Sink can work with a local version of Redis database instance or a cloud based instance whose address will be specified in the Sink spec. Additionally, the specified stream name will be created by the receiver, if they don't already exist.

Getting started

Install

Prerequisites

• Knative Serving (Install instructions here: https://knative.dev/docs/install/any-kubernetes-cluster/#installing-the-serving-component)

• If you are using a local Redis instance, you can skip this step. If you are using a cloud instance of Redis (for example, Redis DB on IBM Cloud), a TLS certificate will need to be configured, prior to installing the event sink.

  Edit the [`tls-secret`](./tls-secret.yaml) Secret to add the TLS Certificate from your cloud instance of Redis to the `TLS_CERT` data key:
  
  ```
  vi config/sink/tls-secret.yaml
  ```
  
  Add your certificate to the file, and save the file. Will be applied in the next step.
  

Create the RedisStreamSink sink definition, and all of its components:

Apply config/sink

ko apply -f config/sink

Example

In this example, you create one Redis Stream event sink that will receive CloudEvent events and then add those items into the mystream stream.

1. Install a local Redis by running this command:

kubectl apply -f samples/redis

2. Create a namespace for this example sink:

kubectl create ns redex

3. Install a Redis Stream Sink example by running this command:

Note: In addition to configuring your TLS Certificate, if you are using a cloud instance of Redis DB, you will need to set the appropriate address in redisstreamsink sink yaml. Here's an example connection string:

address: "rediss://$USERNAME:$PASSWORD@7f41ece8-ccb3-43df-b35b-7716e27b222e.b2b5a92ee2df47d58bad0fa448c15585.databases.appdomain.cloud:32086"

Then, apply samples/sink which creates a Redis Stream Sink resource

kubectl apply -n redex -f samples/sink

4. Verify the Redis Stream Sink is ready:

kubectl get -n redex redisstreamsink.sinks.knative.dev mystream
NAME       URL                                                     AGE   READY   REASON
mystream   http://redistreamsinkmystream.redex.svc.cluster.local   35s   True

5. Send an event to the sink:

curl $(kubectl get ksvc redistreamsinkmystream -ojsonpath='{.status.url}' -n redex) \
 -H "ce-specversion: 1.0" \
 -H "ce-type: dev.knative.sources.redisstream" \
 -H "ce-source: cli" \
 -H "ce-id: 1" \
 -H "datacontenttype: application/json" \
 -d '["fruit", "orange"]'

6. Check a new message has been added to redis:

kubectl exec -n redis svc/redis redis-cli xinfo stream mystream
...
last-entry
1598652372717-0
fruit
orange

7. To cleanup, delete the Redis Stream Sink example, and redex namespace:

kubectl delete -f samples/sink -n redex
kubectl delete ns redex

Reference

Prerequisites

• A Redis installation. Instructions to deploy a local Redis are above.

• An understanding of Redis Stream basics: https://redis.io/topics/streams-intro, and some of the commands specific to Streams: https://redis.io/commands#stream

Resource fields

RedisStreamSink resources are Kubernetes objects. In addition to the standard Kubernetes apiVersion, kind, and metadata, they have the following spec fields:

Field	Value
address	The Redis TCP address
stream	Name of the Redis stream

The sink will provide output information about readiness or errors via the status field on the object once it has been created in the cluster.

Debugging tips

• You can check the Redis Stream Sink resource's status.condition values to diagnose any issues by running either of commands below:

kubectl get redisstreamsinks -n redex
kubectl describe redisstreamsinks mystream -n redex

• You can also read the logs to check for issues with the receiver's deployment:

kubectl get pods -n redex
kubectl logs {podname} -n redex

• You can also read the logs to check for issues with the sink controller's deployment:

kubectl logs redis-controller-manager-0  -n knative-sinks

• KO install issues?

Reference: ko-build/ko#106

Try re-installing KO and setting export GOROOT=$(go env GOROOT)

Configuration options

The config-observability and config-logging ConfigMaps may be used to manage the logging and metrics configuration.