Default unlimited JetStreamLimits differ from unlimited struct used in IsUnlimited()

[choufraise]

What version were you using?

v2.8.1

What environment was the server running in?

N/A

Is this defect reproducible?

Forked the repo and added a simple test in account_claims._test.go verifying the issue. The output from the test:

=== RUN   TestDefaultClaimsShouldBeUnlimited
    account_claims_test.go:1117: expected default limits to be unlimited
    account_claims_test.go:1126: expected default jetstream limits to be unlimited
--- FAIL: TestDefaultClaimsShouldBeUnlimited (0.00s)

Given the capability you are leveraging, describe your expectation?

I would expect the default (unlimited) claims to be consistent with the IsUnlimited() methods.

Given the expectation, what is the defect you are observing?

JetStreamLimits.IsUnlimited() is not returning true for the default JetStreamLimits created when calling NewAccountClaims(). Due to this, OperatorLimits.IsUnlimited() neither return true since it utilizes the o.JetStreamLimits.IsUnlimited() method.

[choufraise]

I would happily create a PR to fix this, but I need to know which JetStreamLimits values should be considered unlimited, either:

• JetStreamLimits{0, 0, 0, 0, 0, 0, 0, false}
• JetStreamLimits{NoLimit, NoLimit, NoLimit, NoLimit, 0, 0, 0, false} (JetStreamLimits{-1, -1, -1, -1, 0, 0, 0, false})

UPDATE: I realize now that the comment in NewAccountClaims

	// Set to unlimited to start. We do it this way so we get compiler
	// errors if we add to the OperatorLimits.

might be very misleading. The JetStreaLimits are initialized as JetStreamLimits{0, 0, 0, 0, 0, 0, 0, false}, which means the following in strict terms:

jwt.JetStreamLimits{
	MemoryStorage:        0,
	DiskStorage:          0,
	Streams:              0,
	Consumer:             0,
	MaxAckPending:        0,
	MemoryMaxStreamBytes: 0,
	DiskMaxStreamBytes:   0,
	MaxBytesRequired:     false,
}

Streams: 0 and Consumer: 0 sounds more like a "deny all" than "unlimited". Is this by design or a bug?

If the same applies to MemoryStorage and DiskStorage, i.e. that 0 actually means "memory/disk not allowed", then this workaround explains a lot. 🤔

UPDATE: I ran a local kuttl test in NAuth verifying that a (supposedly) unlimited Account JWT based on NewAccountClaims() will not allow any JetStreams to be created on that account.

[choufraise]

Apparently, when not touching the JetStreamLimits in the AccountClaims, all its fields are set to zero. Since those fields also are marked with omitempty they won't be sent in the Account JWT. The NATS server will only enable JetStream on an account if either DiskStorage or MemoryStorage is set to a non-zero value. This explains my findings.

I've created a PR to document this in the jwt.NewAccountClaims method in hope that it may save some hairs from turning grey for a fellow dev in the future.

PR: #250