ADR-32.md

Logical User Permissions

Metadata	Value
Date	2022-08-11
Author	@bruth
Status	Proposed
Tags	server

Context and Problem Statement

The crux of a permission is whether a user can publish or subscribe to a subject. This is an appropriate basis for user permissions since every allow/deny can be expressed using a subject. Prior to JetStream, this model was sufficient since there were no abstractions of subjects other than _INBOX.> for the request-reply implementation. The allow_responses permission was introduced to address the generalization of a reply with the introduction of custom inbox prefixes. It would impractible to know and list the inboxes ahead of time.

The introduction of JetStream brought an API which provides the ability to manage and interact with streams and consumers. This API was intended to be internal given the design of the subjects. Client libraries have implemented constructs over top the raw API calls. However, the these higher level constructs never manifested as user permissions.

The concern is that developers need to model permissions based on the internal JS subjects which is both difficult, but also introduces coupling between the developer's application-level need and the API design.

[Context | References | Prior Work]

Permissions are defined for publish or subscribe and list a set of subjects (including wildcards). As noted above, allow_responses is an abstraction to handle the "reply to any inbox" situation.

With the introduction of JetStream, APIs such as add-stream, delete-stream, etc. were introduced. These reduce down to (mostly) a set of request-reply interactions. For example, to create a stream, a request must be made to $JS.API.STREAM.CREATE.<name> where <name> is the named of the stream. To get consumer info a request to $JS.API.CONSUMER.INFO.<stream>.<name> must be allowed.

The question is, why does a developer need to know about these verbose subjects when defining permissions?

Design

Fundamentally, this design is a light abstraction on top of the current way permissions are defined in configuration or JWTs. These new constructs can be converted to a standard permissions map internally.

There are two potential layers to defining user permissions. First, a logical name must be defined for the underlying API subject. This mapping is shown in the table below. In addition to the name, the context (publish or subscribe) can also be inferred. For example, all of the JS APIs use request-reply initiated by the client. So js-create-stream is implicitly a publish-based permission. For subjects that are parameterized based on stream names, consumer names, or subjects, the (...) syntax is used to support specifying these parameters.

Category	Name	Subject	Pub/Sub	Notes
General	pub(subject)	{subject}	pub	Potential alternative to a bare subject string.
*	sub(subject)	{subject}	sub	Same as above.
*	inbox	_INBOX.>	sub
*	inbox(id)	_INBOX_{id}.>	sub	Convention for custom inboxes, so be used with --inbox-prefix for private access.
JetStream	js-all	$JS.API.>	pub
*	js-info	$JS.API.INFO	pub
*	js-create-stream	$JS.API.STREAM.CREATE.*	pub
*	js-create-stream(name)	$JS.API.STREAM.CREATE.{name}	pub
*	js-update-stream	$JS.API.STREAM.UPDATE.*	pub
*	js-update-stream(name)	$JS.API.STREAM.UPDATE.{name}	pub
*	js-delete-stream	$JS.API.STREAM.DELETE.*	pub
*	js-delete-stream(name)	$JS.API.STREAM.DELETE.{name}	pub
*	js-purge-stream	$JS.API.STREAM.PURGE.*	pub
*	js-purge-stream(name)	$JS.API.STREAM.PURGE.{name}	pub
*	js-snapshot-stream	$JS.API.STREAM.SNAPSHOT.*	pub
*	js-snapshot-stream(name)	$JS.API.STREAM.SNAPSHOT.{name}	pub
*	js-snapshot-stream-ack	$JS.API.SNAPSHOT.ACK.*.>	pub
*	js-snapshot-stream-ack(name)	$JS.API.SNAPSHOT.ACK.{name}.>	pub
*	js-restore-stream	$JS.API.STREAM.RESTORE.*	pub
*	js-restore-stream(name)	$JS.API.STREAM.RESTORE.{name}	pub
*	js-snapshot-restore	$JS.API.SNAPSHOT.RESTORE.*.>	pub
*	js-snapshot-restore(name)	$JS.API.SNAPSHOT.RESTORE.{name}.>	pub
*	js-stream-names	$JS.API.STREAM.NAMES	pub
*	js-stream-list	$JS.API.STREAM.LIST	pub
*	js-stream-info	$JS.API.STREAM.INFO.*	pub
*	js-stream-info(name)	$JS.API.STREAM.INFO.{name}	pub
*	js-stream-delete-msg	$JS.API.STREAM.MSG.DELETE.*	pub
*	js-stream-delete-msg(name)	$JS.API.STREAM.MSG.DELETE.{name}	pub
*	js-stream-get-msg	$JS.API.DIRECT.GET.*	pub
*	js-stream-get-msg(name)	$JS.API.DIRECT.GET.{name}	pub
*	js-stream-get-last-subject-msg	$JS.API.DIRECT.GET.*.>	pub
*	js-stream-get-last-subject-msg(stream)	$JS.API.DIRECT.GET.{stream}.>	pub
*	js-stream-get-last-subject-msg(stream, subject)	$JS.API.DIRECT.GET.{stream}.{subject}	pub
*	js-stream-get-last-subject-msg(*, subject)	$JS.API.DIRECT.GET.*.{subject}	pub
*	js-create-ephemeral-consumer	$JS.API.CONSUMER.CREATE.*	pub
*	js-create-ephemeral-consumer(stream)	$JS.API.CONSUMER.CREATE.{stream}	pub
*	js-create-durable-consumer	$JS.API.CONSUMER.DURABLE.CREATE.*.*	pub
*	js-create-durable-consumer(stream)	$JS.API.CONSUMER.DURABLE.CREATE.{stream}.*	pub
*	js-create-durable-consumer(stream, name)	$JS.API.CONSUMER.DURABLE.CREATE.{stream}.{name}	pub
*	js-create-durable-consumer(*, name)	$JS.API.CONSUMER.DURABLE.CREATE.*.{name}	pub
*	js-delete-consumer	$JS.API.CONSUMER.DELETE.*.*	pub
*	js-delete-consumer(stream)	$JS.API.CONSUMER.DELETE.{stream}.*	pub
*	js-delete-consumer(stream, name)	$JS.API.CONSUMER.DELETE.{stream}.{name}	pub
*	js-delete-consumer(*, name)	$JS.API.CONSUMER.DELETE.*.{name}	pub
*	js-consumer-names	$JS.API.CONSUMER.NAMES.*	pub
*	js-consumer-names(stream)	$JS.API.CONSUMER.NAMES.{stream}	pub
*	js-consumer-list	$JS.API.CONSUMER.LIST.*	pub
*	js-consumer-list(stream)	$JS.API.CONSUMER.LIST.{stream}	pub
*	js-consumer-info	$JS.API.CONSUMER.INFO.*.*	pub
*	js-consumer-info(stream)	$JS.API.CONSUMER.INFO.{stream}.*	pub
*	js-consumer-info(stream, name)	$JS.API.CONSUMER.INFO.{stream}.{name}	pub
*	js-consumer-info(*, name)	$JS.API.CONSUMER.INFO.*.{name}	pub
*	js-consumer-next-msg	$JS.API.CONSUMER.MSG.NEXT.*.*	pub
*	js-consumer-next-msg(stream)	$JS.API.CONSUMER.MSG.NEXT.{stream}.*	pub
*	js-consumer-next-msg(stream, name)	$JS.API.CONSUMER.MSG.NEXT.{stream}.{name}	pub
*	js-consumer-next-msg(*, name)	$JS.API.CONSUMER.MSG.NEXT.*.{name}	pub
*	js-consumer-ack-reply	$JS.ACK.*.*.>	pub
*	js-consumer-ack-reply(stream)	$JS.ACK.{stream}.*.>	pub
*	js-consumer-ack-reply(stream, name)	$JS.ACK.{stream}.{name}.>	pub
*	js-consumer-ack-reply(*, name)	$JS.ACK.*.{name}.>	pub
KeyValue	kv-put	$KV.*.>	pub
*	kv-put(bucket)	$KV.{bucket}.>	pub
*	kv-put(bucket, key)	$KV.{bucket}.{key}	pub
*	etc..

TODO: add remaining subjects, leader, peer, advisories, etc.

The second logical tier can be permission groups, often designed as roles, such as js-stream-operator. Parameters, such as stream or consumer names, will be transitively applied to the underlying permissions. The goal of roles is to abstract away a set of permissions for common use cases.

This table shows a few examples.

Name	Permissions	Notes
js-stream-operator	js-create-stream, js-update-stream, js-delete-stream js-purge-stream, js-stream-info, js-snapshot-stream, js-restore-stream
js-stream-operator(name)	js-create-stream(name), js-update-stream(name), etc...
js-stream-user(stream, subject)	publish(subject), js-stream-info(stream), js-stream-get-last-subject-msg(stream, subject)	The publish(subject) is alternative to independently setting a pub-allow.

The best way to model this in configuration is TBD, however, one approach could support allow and deny as top-level keys in the permissions map which would be used exclusively with these new logical permissions.

For example:

accounts: {
  APP: {
    users: [
      {
        user: operator,
        password: operator,
        permissions: {
          allow: [
            "inbox(operator)",
            "js-stream-operator(EVENTS)",
          ]
        }
      },
      {
        user: greeter,
        password: greeter,
        permissions: {
          allow: [
            "inbox(greeter)",
            "sub(services.greeter)",
            "pub(events.greeter.>)",
          ],
          allow_responses: true,
        }
      },
      {
        user: joe,
        password: joe,
        permissions: {
          allow: [
            "inbox(joe)",
            "pub(services.*)",
          ]
        }
      },
      {
        user: sue,
        password: sue,
        permissions: {
          allow: [
            "inbox(sue)",
            "pub(services.*)",
          ]
        }
      }
    ]
  }
}

Decision

[Maybe this was just an architectural decision...]

TODO

Consequences

[Any consequences of this design, such as breaking change or Vorpal Bunnies]

TODO