Using a Load Balancer for External Access to NATS
Using a Load Balancer for External Access to NATS
In the example below, you can find how to use an AWS Network Load Balancer to connect externally to a cluster that has TLS setup.
One-line installer creates a secure cluster named 'nats'
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curl -sSL https://nats-io.github.io/k8s/setup.sh | sh
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Create AWS Network Load Balancer service
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echo '
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apiVersion: v1
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kind: Service
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metadata:
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name: nats-nlb
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namespace: default
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labels:
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app: nats
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annotations:
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service.beta.kubernetes.io/aws-load-balancer-type: "nlb"
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spec:
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type: LoadBalancer
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externalTrafficPolicy: Local
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ports:
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- name: nats
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port: 4222
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protocol: TCP
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targetPort: 4222
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selector:
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app.kubernetes.io/name: nats
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' | kubectl apply -f -
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Check that it worked
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kubectl get svc nats-nlb -o wide
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
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nats-nlb LoadBalancer 10.100.67.123 a18b60a948fc611eaa7840286c60df32-9e96a2af4b5675ec.elb.us-east-2.amazonaws.com 4222:30297/TCP 151m app=nats
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Publish a test message
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nats pub -s nats://a18b60a948fc611eaa7840286c60df32-9e96a2af4b5675ec.elb.us-east-2.amazonaws.com:4222 -creds nsc/nkeys/creds/KO/A/test.creds test.foo bar
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Also, it would be recommended to set no_advertise 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:
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kubectl apply -f https://raw.githubusercontent.com/nats-io/k8s/b55687a97a5fd55485e1af302fbdbe43d2d3b968/nats-server/leafnodes/nats-cluster.yaml
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The configuration map from the NATS cluster that was created can be found below.
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---
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: nats-config
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data:
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nats.conf: |
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pid_file: "/var/run/nats/nats.pid"
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http: 8222
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# debug: true
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ping_interval: 30s
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​
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cluster {
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port: 6222
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no_advertise: true
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​
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routes: [
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nats://nats-0.nats.default.svc:6222
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nats://nats-1.nats.default.svc:6222
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nats://nats-2.nats.default.svc:6222
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]
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}
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​
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leaf {
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port: 7422
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authorization {
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timeout: 3s
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users = [
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{ user: "foo", pass: "bar" }
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]
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}
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}
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Now let's expose the NATS Server by creating an L4 load balancer on Azure:
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kubectl apply -f https://raw.githubusercontent.com/nats-io/k8s/b55687a97a5fd55485e1af302fbdbe43d2d3b968/nats-server/leafnodes/lb.yaml
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Confirm the public IP that was allocated to the
nats-lb service that was created, in this case it is 52.155.49.45:1
kubectl get svc -o wide
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
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kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 81d <none>
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nats ClusterIP None <none> 4222/TCP,6222/TCP,8222/TCP,7777/TCP,7422/TCP,7522/TCP 7h46m app=nats
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nats-lb LoadBalancer 10.0.107.18 52.155.49.45 4222:31161/TCP,7422:30960/TCP 7h40m app=nats
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Notice that the leafnode configuration requires authorization, so in order to connect to it we will need to configuration as follows:
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You can also add a NATS Streaming cluster into the cluster connecting to the port 4222:
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kubectl apply -f https://raw.githubusercontent.com/nats-io/k8s/b55687a97a5fd55485e1af302fbdbe43d2d3b968/nats-server/leafnodes/stan-server.yaml
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Now if you create two NATS Servers that connect to the same leafnode port, they will be able to receive messages to each other:
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nats-server -c leafnodes/leaf.conf -p 4222 &
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nats-server -c leafnodes/leaf.conf -p 4223 &
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Create a subscriber and publish a test message
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nats sub -s localhost:4222 foo &
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nats pub -s localhost:4223 foo hello
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Listening on [foo]
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[#1] Received on [foo] : 'hello'
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