Relations processor

This relations processor plugin emits additional custom relations, which are shown in the
Catalog Graph out of box.

Additionally, you can install the Relations frontend plugin for a better frontend experience with this processor.


Install

$3

First we need to add the @dweber019/backstage-plugin-relations-backend package:

``sh


From your Backstage root directory


yarn --cwd packages/backend add @dweber019/backstage-plugin-relations-backend
`

Then we open the file named packages/backend/src/plugins/catalog.ts, and extend it with:

`ts
import { RelationsEntitiesProcessor } from '@dweber019/backstage-plugin-relations-backend';

export default async function createPlugin(
env: PluginEnvironment,
): Promise {
const builder = await CatalogBuilder.create(env);

builder.addProcessor(RelationEntitiesProcessor.fromConfig(env));

const { processingEngine, router } = await builder.build();
// ..
}
`

Configuration

See the config.d.ts file for a documentation of the configuration.

Here is a simple configuration, which will add an attribute named supporter, which allows relations to User and Group on a Resource.
Additionally, we can use the attribute applicationOwner on Component to allow relations to a User.

`yaml
relationsProcessor:
relations:
- sourceKind: component
targetKinds:
- user
attribute: applicationOwner
pairs:
- incoming: applicationOwnerOf
outgoing: applicationOwnerBy
- sourceKind: resource
targetKinds:
- user
- group
attribute: supporter
multi: true
pairs:
- incoming: supporterOf
outgoing: supportedBy
`

Usage

The above definitions would allow to define the following entities

`yaml
apiVersion: backstage.io/v1alpha1
kind: Resource
metadata:
name: resource-1
spec:
type: db
owner: group:default/group-1
supporter:
- john-doe
- group:default/group-1
---
apiVersion: backstage.io/v1alpha1
kind: Component
metadata:
name: component-1
spec:
type: service
lifecycle: production
owner: group:default/group-1
applicationOwner: user:default/kevin-po
`

$3

It's recommend to use the Relations frontend plugin to add new relations to the filters and set good defaults.

$3

You can use the Well-known Relations between Catalog Entities
relations with this plugin. This is useful if a component is owned by a group and has an application owner, which should have an ownership too.

`yaml
apiVersion: backstage.io/v1alpha1
kind: Component
metadata:
name: component-1
spec:
type: service
lifecycle: production
owner: group:default/group-1
applicationOwner: user:default/kevin-po
`

To enable the owner relation use the following configuration.

`yaml
relationsProcessor:
relations:
- sourceKind: component
targetKinds:
- user
attribute: applicationOwner
pairs:
- incoming: applicationOwnerOf
outgoing: applicationOwnerBy
- incoming: ownerOf
outgoing: ownerBy
`

![](./docs/ownership-card.png)

$3

The backend plugin has support for the new backend system, here's how you can set that up:

In your packages/backend/src/index.ts make the following changes:

`ts
const backend = createBackend();

backend.add(import('@dweber019/backstage-plugin-relations-backend'));

// ... other feature additions

backend.start();
``

> This was not tested and is here for reference

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