[rbac-backend] Error: Plugin 'permission' is already registered

[gluckzhang]

Describe the bug

As mentioned in the documentation here, we need to set up the Backstage permission framework first.

For the new Backend system, I added the following code to packages/backend/src/index.ts:

backend.add(import('@backstage/plugin-permission-backend/alpha'));
backend.add(import('@janus-idp/backstage-plugin-rbac-backend'));

When run yarn dev from the root folder, I get the following error:

[1]             throw new Error(`Plugin '${r.pluginId}' is already registered`);
[1]                   ^
[1] Error: Plugin 'permission' is already registered

I find that both @backstage/plugin-permission-backend/alpha and @janus-idp/backstage-plugin-rbac-backend use the same plugin id (permission), but I am not sure about how to fix it.

Expected Behavior

Backstage is up and running.

What are the steps to reproduce this bug?

1. Follow the example here to setup Backstage permission framework
2. Add @janus-idp/backstage-plugin-rbac-backend
3. run yarn dev from the root folder

Versions of software used and environment

• Backstage 1.27.0
• @backstage/plugin-permission-backend 0.5.42
• @janus-idp/backstage-plugin-rbac-backend@npm 4.10.0

[gluckzhang]

Hi again, after a bit more exploration, I think only adding backend.add(import('@janus-idp/backstage-plugin-rbac-backend')); is sufficient because the documentation also mentions that "this plugin provides a dynamic policy that replaces the traditional one, there's no need to create a policy manually."

In the beginning, the only misleading part to me is that we need to set up the Backstage permission framework first, while Backstage documentation says I need to add backend.add(import('@backstage/plugin-permission-backend/alpha')); in order to enable the permission framework.

Please correct me if the interpretation above is wrong. Furthermore, great job on this RBAC plugin. I see that it also uses Casbin as the rule engine, which is very cool. Thanks!

[PatAKnight]

Sorry for just now getting back to you on this. You are correct that it is misleading and that you only need backend.add(import('@janus-idp/backstage-plugin-rbac-backend'));, the docs haven't been updated completely to reflect the new changes that have been made to Backstage. I'll make some time to review the Setup Permission Framework section to see if it is still relevant. Thanks for this!

[gluckzhang]

Sounds great. Thanks @PatAKnight !