Ce-go-template is a collection of services which process a CloudEvent with a go template. As the go-template includes the sprig functions you can use built-in functionality for collections, strings, math, security/encryption, etc.
A main purpose is to use the services for building knative eventing primitives.
We can group the services according to their role in an event processing chain:
| Group | Knative eventing primitives |
|---|---|
| producers | ContainerSource,Sinkbinding |
| mappers | Sequence,Parallel,Sinkbinding |
| filters | Parallel |
Go-Template transforms an input data structure to a cloudEvent and sends them to an event sink. In knative a producer can be applied as an event source using a ContainerSource or a Sinkbinding
| producer name | Input | Description |
|---|---|---|
| ce-go-template-periodic-producer | void | Sends events frequently based on a configurable time period. See details |
| ce-go-template-http-server-producer | HTTP-Request | Sends events based on an incoming http request. See details |
A mapper transforms an incoming CloudEvent to an outgoing CloudEvent. Depending whether an event sink is present, the new event is either sent to the sink ( send mode), or is the payload of the http response (reply mode)
| mapper name | Description |
|---|---|
| ce-go-template-mapper | Transforms events based on a go-template. See details |
| ce-go-template-http-client-mapper | Transforms an event to HTTP-Request and sends it to a HTTP server. The response is transformed to the outgoing cloud event. See details |
A filter replies with the incoming CloudEvent, if a predicate string built by a go-template resolves to "true". Otherwise the response has no content. In knative a filter can be applied in Flows like Parallel
| filter name | Description |
|---|---|
| ce-go-template-filter | Transforms events to a predicate string based on a go-template. See details |
| ce-go-template-http-client-filter | Transforms an event to HTTP-Request and sends it to a HTTP server. The response is transformed to the outgoing cloud event. See details |
deployment options in knative
# create event display
kn service create event-display --image gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display --cluster-local --scale-min 1
# create event source
kubectl apply -f deployments/producer-display-eventsource.yaml# create event display
kn service create event-display --image gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display --cluster-local --scale-min 1
# create the sink binding
kubectl apply -f deployments/producer-display-sinkbinding.yaml
# create producer service
kubectl create deployment event-producer --image=docker.io/alitari/ce-go-template-periodic-producer# create event display
kn service create event-display --image gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display --cluster-local --scale-min 1
# create event mapper in reply mode
kn service create event-mapper --image=docker.io/alitari/ce-go-template-mapper --cluster-local --scale-min 1
# create sequence
kubectl apply -f deployments/sequence.yaml
# create pingsource
kubectl apply -f deployments/pingsource-sequence.yaml# create event display
kn service create event-display --image gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display --cluster-local --scale-min 1
# create the sink binding
kubectl apply -f deployments/mapper-display-sinkbinding.yaml
# create event mapper in send mode
kn service create event-mapper --image=docker.io/alitari/ce-go-template-mapper --scale-min 1
# make a request
MAPPER_URL=$(kubectl get ksvc event-mapper -o=json | jq -r .status.url)
http POST $MAPPER_URL "content-type: application/json" "ce-specversion: 1.0" "ce-source: http-command" "ce-type: http.demo" "ce-id: 123-abc" name=HaseSee development