NATS Adapter Options

Applies to 1.3.0.

Does this apply to you?

You need to act only if a NatsAdapter() configuration of yours passes one of the values below. Each used to be accepted; each now throws when the adapter is created, so the service fails at start-up and not when the first event is handled.

Option	Refused now	What it did before
options	missing, null or not an object	a missing options failed with a TypeError on the first property read
servers	"", a blank string, [], an array with an empty or non-string entry, any other type	[] made the client connect to its local default address
consumerOptions.ackWait	0, a negative number, NaN, Infinity, a string, a value whose nanoseconds do not fit an exact integer	0 became the 30 s default; -1 made the server redeliver at once
consumerOptions.maxDeliver	0, a number below -1, a fraction, NaN, a string	0 and -2 were accepted; 1.5 failed at the first subscribe() with a server error
consumerOptions.deliverPolicy	anything but "new", "all", "last" (a different case such as "ALL" included)	an unknown value behaved like "new"
consumerOptions	not an object	was accepted

A scaffolded project reads NATS_SERVERS ?? "nats://localhost:4222": if the variable is set but empty (NATS_SERVERS=), the empty string is passed on and NatsAdapter() now throws. Unset the variable or give it a value.

Valid values behave as before. ackWait may still be a fraction of a millisecond count; it is sent to the server as whole nanoseconds.

Behavior that changed without an error

• Metadata. Keys that start with x- and empty values passed in PublishOptions.metadata now reach the handler. Before, the NATS adapter dropped them, so a handler that read x-request-id got nothing on NATS and a value on Redis. Only x-event-id stays the adapter's own. If a handler relied on the absence of such a key, or counted ctx.metadata entries, check it.
• Logs. The adapter now logs [EventBus/NATS] lines in three situations: the last delivery maxDeliver allows was given back, the server lost a consumer together with its stream (and the consumer is created again), and a consumer was deleted while its stream still exists. See NATS JetStream.
• Resumption. A subscription whose stream was deleted and created again now receives events again; before it stayed silent.

Required changes

Replace the refused value with a valid one, or remove it to get the default:

// before: each of these was accepted
NatsAdapter({ servers: [], consumerOptions: { ackWait: 0, maxDeliver: 0, deliverPolicy: 'ALL' } });

// after
NatsAdapter({ servers: 'nats://localhost:4222', consumerOptions: { deliverPolicy: 'all' } });

Verify

Start the service: the constructor throws with the option's name and the allowed values if a refused value is still in use. To see the new metadata behavior, publish with metadata: { 'x-request-id': 'r1' } and read ctx.metadata.get('x-request-id') in the handler.