Brigade CloudEvents Gateway

This is a work-in-progress Brigade 2 compatible gateway that receives CloudEvents over HTTP/S and propagates them into Brigade 2's event bus.

Installation

Prerequisites:

A Kubernetes cluster:
- For which you have the admin cluster role
- That is already running Brigade 2
- Capable of provisioning a public IP address for a service of type LoadBalancer. (This means you won't have much luck running the gateway locally in the likes of kind or minikube unless you're able and willing to mess with port forwarding settings on your router, which we won't be covering here.)
kubectl, helm (commands below require Helm 3.7.0+), and brig (the Brigade 2 CLI)

1. Create a Service Account for the Gateway

Note: To proceed beyond this point, you'll need to be logged into Brigade 2 as the "root" user (not recommended) or (preferably) as a user with the ADMIN role. Further discussion of this is beyond the scope of this documentation. Please refer to Brigade's own documentation.

Using Brigade 2's brig CLI, create a service account for the gateway to use:

$ brig service-account create \
    --id brigade-cloudevents-gateway \
    --description brigade-cloudevents-gateway

Make note of the token returned. This value will be used in another step. It is your only opportunity to access this value, as Brigade does not save it.

Authorize this service account to create new events:

$ brig role grant EVENT_CREATOR \
    --service-account brigade-cloudevents-gateway \
    --source brigade.sh/cloudevents

Note: The --source brigade.sh/cloudevents option specifies that this service account can be used only to create events having a value of brigade.sh/cloudevents in the event's source field. This is a security measure that prevents the gateway from using this token for impersonating other gateways.

2. Install the CloudEvents Gateway

For now, we're using the GitHub Container Registry (which is an OCI registry) to host our Helm chart. Helm 3.7 has experimental support for OCI registries. In the event that the Helm 3.7 dependency proves troublesome for users, or in the event that this experimental feature goes away, or isn't working like we'd hope, we will revisit this choice before going GA.

First, be sure you are using Helm 3.7.0 or greater and enable experimental OCI support:

$ export HELM_EXPERIMENTAL_OCI=1

As this chart requires custom configuration as described above to function properly, we'll need to create a chart values file with said config.

Use the following command to extract the full set of configuration options into a file you can modify:

$ helm inspect values oci://ghcr.io/brigadecore/brigade-cloudevents-gateway \
    --version v0.2.0 > ~/brigade-cloudevents-gateway-values.yaml

Edit ~/brigade-cloudevents-gateway-values.yaml, making the following changes:

host: Set this to the host name where you'd like the gateway to be accessible.
brigade.apiAddress: Address of the Brigade API server, beginning with https://
brigade.apiToken: Service account token from step 2
tokens: This field should map CloudEvent sources to tokens (shared secrets) that can be used by clients to send cloud events for each source.

Note that a Brigade event's source/type fields and a CloudEvent's source/type fields are similar in that they are both metadata that enable event routing, but will be different in value. The CloudEvent Gateway emits Brigade events into Brigade's event bus with the source brigade.sh/cloudevents and type cloudevent. The CloudEvent's original source and type become qualifiers on the Brigade event.

For the example in sections 4 and 5 below, edit the token so that source example/uri authenticates using the token (shared secret) MySharedSecret.

Save your changes to ~/brigade-cloudevents-gateway-values.yaml and use the following command to install the gateway using the above customizations:

$ helm install brigade-cloudevents-gateway \
    oci://ghcr.io/brigadecore/brigade-cloudevents-gateway \
    --version v0.2.0 \
    --create-namespace \
    --namespace brigade-cloudevents-gateway \
    --values ~/brigade-cloudevents-gateway-values.yaml

3. (RECOMMENDED) Create a DNS Entry

If you installed the gateway without enabling support for an ingress controller, this command should help you find the gateway's public IP address:

$ kubectl get svc brigade-cloudevents-gateway \
    --namespace brigade-cloudevents-gateway \
    --output jsonpath='{.status.loadBalancer.ingress[0].ip}'

If you overrode defaults and enabled support for an ingress controller, you probably know what you're doing well enough to track down the correct IP without our help. 😉

With this public IP in hand, edit your name servers and add an A record pointing your domain to the public IP.

4. Add a Brigade Project

You can create any number of Brigade projects (or modify an existing one) to listen for CloudEvents that were sent to your gateway and, in turn, emitted into Brigade's event bus:

apiVersion: brigade.sh/v2-beta
kind: Project
metadata:
  id: cloudevents-demo
description: A project that demonstrates integration with CloudEvents
spec:
  eventSubscriptions:
  - source: brigade.sh/cloudevents
    types:
    - cloudevent
    qualifiers:
      source: example/uri
      type: example.type
  workerTemplate:
    defaultConfigFiles:
      brigade.js: |-
        const { events } = require("@brigadecore/brigadier");

        events.on("brigade.sh/cloudevents", "cloudevent", () => {
          console.log("Received an event from the brigade.sh/cloudevents gateway!");
        });

        events.process();

Assuming this file were named project.yaml, you can create the project like so:

$ brig project create --file project.yaml

5. Create a CloudEvent

You can use the following curl command to send a CloudEvent that should be subscribed to by the example project in the previous section:

$ curl -i -k -X POST \
    -H "ce-specversion: 1.0" \
    -H "ce-id: 1234-1234-1234" \
    -H "ce-source: example/uri" \
    -H "ce-type: example.type" \
    -H "Authorization: Bearer MySharedSecret" \
    https://<public IP or host name here>/events

If the gateway accepts the request, output will look like this:

HTTP/1.1 200 OK
Date: Tue, 03 Aug 2021 19:13:37 GMT
Content-Length: 0

To confirm that the gateway emitted a corresponding Brigade event into Brigade's event bus, list the events for the cloudevents-demo project (created in section 4), which is subscribed to such events:

$ brig event list --project cloudevents-demo

Full coverage of brig commands is beyond the scope of this documentation, but at this point, additional brig commands can be applied to monitor the event's status and view logs produced in the course of handling the event.

Events Received and Emitted by this Gateway

CloudEvents received by this gateway are emitted into Brigade's event bus as native Brigade events with source brigade.sh/cloudevents and type cloudevent. The CloudEvent's original source and type are added to the native Brigade event as qualifiers with the keys source and type, respectively. The CloudEvent's original data (taken from a data field in the request body) becomes the value of the native Brigade event's payload field.

Examples Projects

See examples/ for complete Brigade projects that demonstrate various scenarios.

Contributing

The Brigade project accepts contributions via GitHub pull requests. The Contributing document outlines the process to help get your contribution accepted.

Support & Feedback

We have a slack channel! Kubernetes/#brigade Feel free to join for any support questions or feedback, we are happy to help. To report an issue or to request a feature open an issue here

Code of Conduct

Participation in the Brigade project is governed by the CNCF Code of Conduct.

czunker / brigade-cloudevents-gateway