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nats-on-kubernetes/nats-external-nlb.md
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# Using a Load Balancer for External Access to NATS
Although it is not recommended in general to use a load balancer with NATS for external access, sometimes due to policy it might help to use one. If that is the case, then one option would be to use an L4 load balancer that has raw tcp support.
## Using a Load Balancer for External Access to NATS
In the example below, you can find how to use an [AWS Network Load Balancer](https://docs.aws.amazon.com/elasticloadbalancing/latest/network/introduction.html) to connect externally to a cluster that has TLS setup.
@ -40,3 +38,95 @@ $ nats-pub -s nats://a18b60a948fc611eaa7840286c60df32-9e96a2af4b5675ec.elb.us-ea
Also, it would be recommended to set [no\_advertise](../nats-server/configuration/clustering/cluster_config.md) to `true` in order to avoid gossiping internal addresses from pods in Kubernetes to NATS clients.
## Setting up a NATS Server with external access on Azure
With the following, you can create a 3-node NATS Server cluster:
```sh
kubectl apply -f https://raw.githubusercontent.com/nats-io/k8s/b55687a97a5fd55485e1af302fbdbe43d2d3b968/nats-server/leafnodes/nats-cluster.yaml
```
The configuration map from the NATS cluster that was created can be found below.
```yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
name: nats-config
data:
nats.conf: |
pid_file: "/var/run/nats/nats.pid"
http: 8222
# debug: true
ping_interval: 30s
cluster {
port: 6222
no_advertise: true
routes: [
nats://nats-0.nats.default.svc:6222
nats://nats-1.nats.default.svc:6222
nats://nats-2.nats.default.svc:6222
]
}
leaf {
port: 7422
authorization {
timeout: 3s
users = [
{ user: "foo", pass: "bar" }
]
}
}
```
Now let's expose the NATS Server by creating an L4 load balancer on Azure:
```sh
kubectl apply -f https://raw.githubusercontent.com/nats-io/k8s/b55687a97a5fd55485e1af302fbdbe43d2d3b968/nats-server/leafnodes/lb.yaml
```
Confirm the public IP that was allocated to the `nats-lb` service that was created, in this case it is `52.155.49.45`:
```
$ kubectl get svc -o wide
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 81d <none>
nats ClusterIP None <none> 4222/TCP,6222/TCP,8222/TCP,7777/TCP,7422/TCP,7522/TCP 7h46m app=nats
nats-lb LoadBalancer 10.0.107.18 52.155.49.45 4222:31161/TCP,7422:30960/TCP 7h40m app=nats
```
Notice that the leafnode configuration requires authorization, so in order to connect to it we will need to configuration as follows:
```ruby
leaf {
remotes = [
{
url: "nats://foo:bar@52.155.49.45:7422"
}
]
}
```
You can also add a NATS Streaming cluster into the cluster connecting to the port 4222:
```sh
kubectl apply -f https://raw.githubusercontent.com/nats-io/k8s/b55687a97a5fd55485e1af302fbdbe43d2d3b968/nats-server/leafnodes/stan-server.yaml
```
Now if you create two NATS Servers that connect to the same leafnode port, they will be able to receive messages to each other:
```sh
nats-server -c leafnodes/leaf.conf -p 4222 &
nats-server -c leafnodes/leaf.conf -p 4223 &
$ nats-sub -s localhost:4222 foo &
$ nats-pub -s localhost:4223 foo hello
Listening on [foo]
[#1] Received on [foo] : 'hello'
```