This repository contains a set of Backstage plugins for Knative and their respective backends.
See Event Mesh plugin README file for more information.
The architecture of the plugin is as follows:
Kubernetes Backstage
┌────────────────────┐ ┌───────────────────────────────────────────────┐
│ │ │ Plugin │
│ ┌───────────────┐ │ │ ┌─────────────────┐ ┌───────────────┐ │
│ │ │ │ │ │ │ │ │ │
│ │ Backend ◄──┼────┐ │ │ ┌─────────────┐ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │
│ └───────┬───────┘ │ └──────┼─┼─┤ Provider ├─┼────────► │ │
│ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ └─────────────┘ │ │ │ │
│ │ │ │ │ │ │ │ │
│ ┌───────▼───────┐ │ │ │ │ │ │ │
│ │ │ │ │ │ ┌────────┼────────┤ Catalog │ │
│ │ API Server │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │
│ └───────────────┘ │ │ │ ┌──────▼──────┐ │ │ │ │
│ │ │ │ │ │ │ │ │ │
└────────────────────┘ │ │ │ Processor ├─┼────────► │ │
│ │ │ │ │ │ │ │
│ │ └─────────────┘ │ │ │ │
│ │ │ │ │ │
│ └─────────────────┘ └───────────────┘ │
└───────────────────────────────────────────────┘
The plugin use providers (and possibly other mechanisms) to communicate with a special backend-for-frontend.
This backend talks to the Kubernetes API server to get information about the resources in the cluster.
---
title: Overall
---
flowchart TD
Start --> FetchBrokers
FetchBrokers --> ProcessBrokers
ProcessBrokers --> FetchEventTypes
FetchEventTypes --> ProcessEventTypes
ProcessEventTypes --> FetchTriggers
FetchTriggers --> ProcessTriggers
---
title: ProcessBrokers
---
flowchart LR
GetNextBroker --> CreateDTO
---
title: ProcessEventTypes
---
flowchart TD
GetEventType[Get next event type]
CheckRef{spec.ref exists?}
RefIsABrokerInTheBrokerMap{ref is a broker in the previously <br> built broker map?}
RegisterEventType[Add event type to broker DTO's `providedEventTypes` list]
DontRegisterEventType[Don't relate the event type to any broker]
Done[Done]
GetEventType --> CheckRef
CheckRef --> |Yes| RefIsABrokerInTheBrokerMap
RefIsABrokerInTheBrokerMap --> |Yes| RegisterEventType
CheckRef --> |No| DontRegisterEventType
RefIsABrokerInTheBrokerMap --> |No| DontRegisterEventType
RegisterEventType --> Done
DontRegisterEventType --> Done
---
title: ProcessTriggers
---
flowchart TD
GetTrigger[Get next trigger]
CheckSubscriberRef{spec.subscriber.ref <br> exists?}
FetchSubscriberRef[Fetch subscriber resource]
CheckSubscriberLabel{Subscriber has the <br> Backstage label}
CheckEventType{Trigger has an <br> event type}
RegisterSingleRelation[Register `ConsumedBy` relation <br> for eventType and subscriber]
RegisterRelation[Register `ConsumedBy` relation <br> for eventType and subscriber]
Ignore[Ignore trigger]
Done[Done]
GetTrigger --> CheckSubscriberRef
CheckSubscriberRef --> |Yes| FetchSubscriberRef
FetchSubscriberRef --> CheckSubscriberLabel
CheckSubscriberLabel --> |Yes| CheckEventType
CheckEventType --> |Yes| RegisterSingleRelation
CheckEventType --> |No| FetchAllEventTypesForBroker
FetchAllEventTypesForBroker --> ForEachEventType --> RegisterRelation
RegisterSingleRelation --> Done
RegisterRelation --> Done
CheckSubscriberLabel --> |No| Ignore
CheckSubscriberRef --> |No| Ignore
Ignore --> Done
CheckSubscriberRef -.- CheckSubscriberRefNote["We can't collect subscriber information using the URL. <br> So, let's simply check the subsciber ref."]
CheckSubscriberLabel -.- CheckSubscriberLabelNote["The target is to show what resource is using what event types. <br> However, Backstage will only show the resource if it has a special label. <br> So, if that label is missing, simply ignore the subscriber."]
CheckEventType -.- CheckEventTypeNote["If the trigger has an event type filter, <br> that means the subscriber is subscribed to that event. <br> If not, the subscriber is subscribed to all events from this trigger. <br> Please note that we ignore other filtering mechanisms such as 'source'."]
CheckSubscriberRefNote:::note
CheckSubscriberLabelNote:::note
CheckEventTypeNote:::note
classDef note fill:yellow
The backend is a Go project that runs in a Kubernetes cluster.
Prerequisites:
- To run the backend, you need to have a Kubernetes cluster running and the
kubectlcommand line tool installed. - Also, you need
koinstalled and configured.
# Build and deploy the backend
ko apply -f ./backends/config/100-eventmesh/Check that the backend is running:
# proxy the backend service
kubectl port-forward -n knative-eventing svc/eventmesh-backend 8080:8080
# check that the backend is running
curl -v http://localhost:8080/
{
"eventTypes":[{"name":"test-event-type","namespace":"default","type":"foo","uid":"8a44f223-c2e5-4cc1-a578-cc81c6ea2898"}],
"brokers":[{"name":"default","namespace":"default","uid":"d44e3cfa-5866-43fd-a8ed-b3a3436beecd"}]
}The plugin is enabled inside the Backstage instance that is in ./backstage directory.
Prerequisites:
- To run the plugin, you need to have the
yarncommand line tool installed.
First, install dependencies:
# Install dependencies
cd ./backstage
yarn install --frozen-lockfileThe default configuration of the plugin is to use the backend at http://localhost:8080.
Ensure the backend is running, and then, start the Backstage instance:
cd ./backstage
yarn devBy default, Backstage App can be accessed at http://localhost:3000.
If Backstage App is running as a Kubernetes deployment, it could be accessed over ingress by doing changes specified here.
You need act installed: https://github.com/nektos/act
# Specify the job to run
act -j '<job name>'
# ex:
# act -j 'publish-release-snapshot-on-npm'
# if having issues on Apple Silicon, use:
# act --rm --container-architecture linux/amd64 -j 'publish-release-snapshot-on-npm'