mirror of https://github.com/knative/docs.git
160 lines
4.3 KiB
Markdown
160 lines
4.3 KiB
Markdown
# Cloud Events - Go
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A simple web app written in Go that can receive and send Cloud Events that you
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can use for testing. It supports running in two modes:
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1. The default mode has the app reply to your input events with the output
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event, which is simplest for demonstrating things working in isolation, but
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is also the model for working for the Knative Eventing `Broker` concept.
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2. `K_SINK` mode has the app send events to the destination encoded in
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`$K_SINK`, which is useful to demonstrate how folks can synthesize events to
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send to a Service or Broker when not initiated by a Broker invocation (e.g.
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implementing an event source)
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The application will use `$K_SINK`-mode whenever the environment variable is
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specified.
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Do the following steps to create the sample code and then deploy the app to your
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cluster. You can also download a working copy of the sample, by running the
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following commands:
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```bash
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git clone https://github.com/knative/docs.git knative-docs
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cd knative-docs/code-samples/serving/cloudevents/cloudevents-go
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```
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## Before you begin
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- A Kubernetes cluster with Knative installed and DNS configured. See
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[Install Knative Serving](https://knative.dev/docs/install/serving/install-serving-with-yaml).
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- [Docker](https://www.docker.com) installed and running on your local machine,
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and a Docker Hub account configured (we'll use it for a container registry).
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## The sample code.
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1. If you look in `cloudevents.go`, you will see two key functions for the
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different modes of operation:
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```go
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func (recv *Receiver) ReceiveAndSend(ctx context.Context, event cloudevents.Event) cloudevents.Result {
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// This is called whenever an event is received if $K_SINK is set, and sends a new event
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// to the url in $K_SINK.
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}
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func (recv *Receiver) ReceiveAndReply(ctx context.Context, event cloudevents.Event) (*cloudevents.Event, cloudevents.Result) {
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// This is called whenever an event is received if $K_SINK is NOT set, and it replies with
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// the new event instead.
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}
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```
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1. Choose how you would like to build the application:
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=== "Dockerfile"
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If you look in `Dockerfile`, you will see a method for pulling in the
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dependencies and building a small Go container based on Alpine. You can build
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and push this to your registry of choice via:
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```bash
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docker build -t <image> .
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docker push <image>
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```
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=== "ko"
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You can use [`ko`](https://github.com/google/ko) to build and push just the image with:
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```bash
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ko publish github.com/knative/docs/code-samples/serving/cloudevents/cloudevents-go
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```
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However, if you use `ko` for the next step, this is not necessary.
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1. Choose how you would like to deploy the application:
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=== "yaml (with Dockerfile)"
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If you look in `service.yaml`, take the `<image>` name you used earlier and insert it
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into the `image:` field, then run:
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```bash
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kubectl apply -f service.yaml
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```
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=== "yaml (with ko)"
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If using `ko` to build and push:
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```bash
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ko apply -f service.yaml
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```
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=== "kn (with Dockerfile)"
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If using `kn` to deploy:
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```bash
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kn service create cloudevents-go --image=<IMAGE>
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```
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=== "kn (with ko)"
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You can compose `kn` and `ko` to build and deploy with a single step using:
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```bash
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kn service create cloudevents-go --image=$(ko publish github.com/knative/docs/code-samples/serving/cloudevents/cloudevents-go)
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```
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## Testing the sample
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Get the URL for your Service with:
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```bash
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$ kubectl get ksvc
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NAME URL LATESTCREATED LATESTREADY READY REASON
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cloudevents-go http://cloudevents-go.default.1.2.3.4.sslip.io cloudevents-go-ss5pj cloudevents-go-ss5pj True
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```
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Then send a cloud event to it with:
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```bash
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$ curl -X POST \
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-H "content-type: application/json" \
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-H "ce-specversion: 1.0" \
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-H "ce-source: curl-command" \
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-H "ce-type: curl.demo" \
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-H "ce-id: 123-abc" \
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-d '{"name":"Dave"}' \
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http://cloudevents-go.default.1.2.3.4.sslip.io
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```
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You will get back:
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```bash
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{"message":"Hello, Dave"}
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```
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## Removing the sample app deployment
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To remove the sample app from your cluster, delete the service record:
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```bash
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kubectl delete --filename service.yaml
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```
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