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://gwu:gwp@localhost:7222"},
{name: "B", url: "nats://gwu:gwp@localhost:7333"},
{name: "C", url: "nats://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
[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 |
By using urls and an array, you can specify a list of endpoints that
form part of a cluster as below. A NATS Server will pick one of those
addresses randomly and only establish a single outbound gateway
connection to one of the members from another cluster:
gateway {
name: "DC-A"
listen: "localhost:7222"
gateways: [
{name: "DC-A", urls: ["nats://localhost:7222", "nats://localhost:7223", "nats://localhost:7224"]},
{name: "DC-B", urls: ["nats://localhost:7332", "nats://localhost:7333", "nats://localhost:7334"]},
{name: "DC-C", urls: ["nats://localhost:7442", "nats://localhost:7333", "nats://localhost:7335"]}
]
}