https://github.com/alitari/ce-go-template
process CloudEvent with go template
https://github.com/alitari/ce-go-template
cloudevent cloudevents go-template golang k8s knative knative-eventing kubernetes sprig-functions
Last synced: 27 days ago
JSON representation
process CloudEvent with go template
- Host: GitHub
- URL: https://github.com/alitari/ce-go-template
- Owner: alitari
- License: mit
- Created: 2020-10-23T13:57:04.000Z (over 5 years ago)
- Default Branch: main
- Last Pushed: 2020-12-06T13:04:55.000Z (over 5 years ago)
- Last Synced: 2024-06-20T22:37:14.804Z (almost 2 years ago)
- Topics: cloudevent, cloudevents, go-template, golang, k8s, knative, knative-eventing, kubernetes, sprig-functions
- Language: Go
- Homepage:
- Size: 209 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Ce-go-template
[](https://goreportcard.com/report/github.com/alitari/ce-go-template)
[](https://codecov.io/gh/alitari/ce-go-template)
`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](https://knative.dev/docs/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] |
## producers
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](docs/periodic-producer.md)
| ce-go-template-http-server-producer | HTTP-Request | Sends events based on an incoming http request. See [details](docs/http-server-producer.md) |
## mappers
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](docs/ce-go-template-mapper.md)|
| 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](docs/ce-go-template-http-client-mapper.md) |
## filters
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](docs/ce-go-template-filter.md)|
| 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](docs/ce-go-template-http-client-mapper.md) |
## deployment options in [knative]
### event producer as container source
```bash
# 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
```
### event producer with sinkbinding
```bash
# 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
```
### event mapper in sequence
```bash
# 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
```
### event mapper as subject
```bash
# 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=Hase
```
## development
See [development](./docs/development.md)
[CloudEvent]: https://github.com/cloudevents/spec
[knative]: https://knative.dev/
[CloudEvents spec]: https://github.com/cloudevents/spec/blob/v1.0/spec.md
[CloudEvent Data]: https://github.com/cloudevents/spec/blob/v1.0/spec.md#event-data
[CloudEvent context attributes]: https://github.com/cloudevents/spec/blob/v1.0/spec.md#context-attributes
[go template]: https://golang.org/pkg/text/template/
[ContainerSource]: https://knative.dev/docs/eventing/sources/containersource/
[Sinkbinding]: https://knative.dev/docs/eventing/sources/sinkbinding/
[Sequence]: https://knative.dev/docs/eventing/flows/sequence/
[Parallel]: https://knative.dev/docs/eventing/flows/parallel/
[httpie]: https://httpie.org/
[Flows]: https://knative.dev/docs/eventing/flows/
[event sink]: https://redhat-developer-demos.github.io/knative-tutorial/knative-tutorial-eventing/eventing-src-to-sink.html#eventing-sink
[JSON representation of CloudEvent]: https://github.com/cloudevents/spec/blob/v1.0/json-format.md
[sprig functions]: http://masterminds.github.io/sprig/