nats.docs/gateways/gateway.md

Gateway Configuration

The gateway configuration block is similar to a cluster block:

gateway {
	name: "A"
	listen: "localhost:7222"
	authorization {
		user: gwu
		password: gwp
	}

	gateways: [
		{name: "A", url: "nats-gateway://gwu:gwp@localhost:7222"},
		{name: "B", url: "nats-gateway://gwu:gwp@localhost:7333"},
		{name: "C", url: "nats-gateway://gwu:gwp@localhost:7444"},
	]
}

One difference is that instead of routes you specify gateways. As expected self-gateway connections are ignored, so you can share gateway configurations with minimal fuzz.

Starting a server:

> nats-server -c A.conf
[85803] 2019/05/07 10:50:55.902474 [INF] Starting nats-server version 2.0.0-RC11
[85803] 2019/05/07 10:50:55.902547 [INF] Git commit [not set]
[85803] 2019/05/07 10:50:55.903669 [INF] Gateway name is A
[85803] 2019/05/07 10:50:55.903684 [INF] Listening for gateways connections on localhost:7222
[85803] 2019/05/07 10:50:55.903696 [INF] Address for gateway "A" is localhost:7222
[85803] 2019/05/07 10:50:55.903909 [INF] Listening for client connections on 0.0.0.0:4222
[85803] 2019/05/07 10:50:55.903914 [INF] Server id is NBHUDBF3TVJSWCDPG2HSKI4I2SBSPDTNYEXEMOFAZUZYXVA2IYRUGPZU
[85803] 2019/05/07 10:50:55.903917 [INF] Server is ready
[85803] 2019/05/07 10:50:56.830669 [INF] 127.0.0.1:50892 - gid:2 - Processing inbound gateway connection
[85803] 2019/05/07 10:50:56.830673 [INF] 127.0.0.1:50891 - gid:1 - Processing inbound gateway connection
[85803] 2019/05/07 10:50:56.831079 [INF] 127.0.0.1:50892 - gid:2 - Inbound gateway connection from "C" (NBHWDFO3KHANNI6UCEUL27VNWL7NWD2MC4BI4L2C7VVLFBSMZ3CRD7HE) registered
[85803] 2019/05/07 10:50:56.831211 [INF] 127.0.0.1:50891 - gid:1 - Inbound gateway connection from "B" (ND2UJB3GFUHXOQ2UUMZQGOCL4QVR2LRJODPZH7MIPGLWCQRARJBU27C3) registered
[85803] 2019/05/07 10:50:56.906103 [INF] Connecting to explicit gateway "B" (localhost:7333) at 127.0.0.1:7333
[85803] 2019/05/07 10:50:56.906104 [INF] Connecting to explicit gateway "C" (localhost:7444) at 127.0.0.1:7444
[85803] 2019/05/07 10:50:56.906404 [INF] 127.0.0.1:7333 - gid:3 - Creating outbound gateway connection to "B"
[85803] 2019/05/07 10:50:56.906444 [INF] 127.0.0.1:7444 - gid:4 - Creating outbound gateway connection to "C"
[85803] 2019/05/07 10:50:56.906647 [INF] 127.0.0.1:7444 - gid:4 - Outbound gateway connection to "C" (NBHWDFO3KHANNI6UCEUL27VNWL7NWD2MC4BI4L2C7VVLFBSMZ3CRD7HE) registered
[85803] 2019/05/07 10:50:56.906772 [INF] 127.0.0.1:7333 - gid:3 - Outbound gateway connection to "B" (ND2UJB3GFUHXOQ2UUMZQGOCL4QVR2LRJODPZH7MIPGLWCQRARJBU27C3) registered

Once all the gateways are up, these clusters of one will forward messages as expected:

> nats-pub -s localhost:4444 foo bar
Published [foo] : 'bar'

# On a different session...
> nats-sub -s localhost:4333 ">"
Listening on [>]
[#1] Received on [foo]: 'bar'

Gateway Configuration Block

Property	Description
advertise	Hostport <host>:<port> to advertise to other gateways.
authorization	Authorization block (same as other nats-server authorization configuration).
connect_retries	Number of times the server will try to connect to a discovered gateway.
gateways	List of Gateway entries - see below.
host	Interface where the gateway will listen for incomming gateway connections.
listen	Combines host and port as <host>:<port>
name	Name for this cluster, all gateways belonging to the same cluster, should specify the same name.
port	Port where the gateway will listen for incomming gateway connections.
reject_unknown	If true, gateway will reject connections from gateways that are not configured in gateways.
tls	TLS configuration block (same as other nats-server tls configuration).

Gateway Entry

The gateways configuration block is a list of gateway entries with the following properties:

Property	Description
name	Gateway name.
url	Hostport <host>:<port> describing where the remote gateway can be reached. If multiple IPs are returned, one is randomly selected.
urls	A list of url