Creating a NATS Super Cluster in Digital Ocean with Helm
Let's create a super cluster using NATS Gateways. First let's create 3 different clusters in NYC, Amsterdam, and San Francisco:
doctl kubernetes cluster create nats-k8s-nyc1 --count 3 --region nyc1
doctl kubernetes cluster create nats-k8s-sfo2 --count 3 --region sfo2
doctl kubernetes cluster create nats-k8s-ams3 --count 3 --region ams3
Next, open up the firewall across the 3 regions to be able to access the client, leafnode and gateways ports:
for firewall in `doctl compute firewall list | tail -n 3 | awk '{print $1}'`; do
doctl compute firewall add-rules $firewall --inbound-rules protocol:tcp,ports:4222,address:0.0.0.0/0
doctl compute firewall add-rules $firewall --inbound-rules protocol:tcp,ports:7422,address:0.0.0.0/0
doctl compute firewall add-rules $firewall --inbound-rules protocol:tcp,ports:7522,address:0.0.0.0/0
done
For this setup, we will create a super cluster using the external IPs from the nodes of the 3 clusters. For a production type of setup, it is recommended to use a DNS entry and an A record for each one of the servers.
for ctx in do-ams3-nats-k8s-ams3 do-nyc1-nats-k8s-nyc1 do-sfo2-nats-k8s-sfo2; do
echo "name: $ctx"
for externalIP in `kubectl --context $ctx get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}'`; do
echo "- nats://$externalIP:7522";
done
echo
done
The Helm definition would look as follows for the 3 clusters:
# super-cluster.yaml
nats:
externalAccess: true
logging:
debug: false
trace: false
cluster:
enabled: true
gateway:
enabled: true
# NOTE: defined via --set gateway.name="$ctx"
# name: $ctx
gateways:
- name: do-ams3-nats-k8s-ams3
urls:
- nats://142.93.251.181:7522
- nats://161.35.12.245:7522
- nats://161.35.2.153:7522
- name: do-nyc1-nats-k8s-nyc1
urls:
- nats://142.93.251.181:7522
- nats://161.35.12.245:7522
- nats://161.35.2.153:7522
- name: do-sfo2-nats-k8s-sfo2
urls:
- nats://142.93.251.181:7522
- nats://161.35.12.245:7522
- nats://161.35.2.153:7522
natsbox:
enabled: true
Let's deploy the super cluster with Helm using the name of cluster as the name of the gateway:
for ctx in do-ams3-nats-k8s-ams3 do-nyc1-nats-k8s-nyc1 do-sfo2-nats-k8s-sfo2; do
helm --kube-context $ctx install nats nats/nats -f super-cluster.yaml --set gateway.name=$ctx
done
That's it! It should now be possible to send some messages across regions:
# Start subscription in Amsterdam
nats-box:~# kubectl --context do-ams3-nats-k8s-ams3 exec -it nats-box -- /bin/sh -l
nats-box:~# nats sub -s nats hello
# Send messages from San Francisco region
nats-box:~# kubectl --context do-sfo2-nats-k8s-sfo2 exec -it nats-box -- /bin/sh -l
nats-box:~# nats pub -s nats hello 'Hello World!'
# From outside of k8s can use the external IPs
nats sub -s 142.93.251.181 hello
nats pub -s 161.35.2.153 hello 'Hello World!'

Using leafnodes and NATS super clusters to communicate across regions

You can also create a multi-region NATS topology by using leafnodes connecting to a NATS super cluster (which could also be a much simpler way!).
doctl kubernetes cluster create nats-k8s-nyc1 --count 3 --region nyc1
doctl kubernetes cluster create nats-k8s-sfo2 --count 3 --region sfo2
doctl kubernetes cluster create nats-k8s-ams3 --count 3 --region ams3
Next, open up the firewall across the 3 regions to be able to access the client, leafnode and gateways ports:
for firewall in `doctl compute firewall list | tail -n 3 | awk '{print $1}'`; do
doctl compute firewall add-rules $firewall --inbound-rules protocol:tcp,ports:4222,address:0.0.0.0/0
done
The Helm definition would look as follows for the 3 clusters:
# nats.yaml
leafnodes:
enabled: true
remotes:
- url: tls://connect.ngs.global:7422
credentials:
secret:
name: ngs-creds
key: NGS.creds
natsbox:
enabled: true
Let's deploy the super cluster with Helm using the name of cluster as the name of the gateway:
for ctx in do-ams3-nats-k8s-ams3 do-nyc1-nats-k8s-nyc1 do-sfo2-nats-k8s-sfo2; do
kubectl --context $ctx create secret generic ngs-creds --from-file $HOME/.nkeys/creds/synadia/NGS/NGS.creds
helm --kube-context $ctx install nats nats/nats -f nats.yaml
done
It should now be possible to send some messages across regions:
# Start subscription in Amsterdam
nats-box:~# kubectl --context do-ams3-nats-k8s-ams3 exec -it nats-box -- /bin/sh -l
nats-box:~# nats-sub -s nats hello
# Send messages from San Francisco region
nats-box:~# kubectl --context do-sfo2-nats-k8s-sfo2 exec -it nats-box -- /bin/sh -l
nats-box:~# nats-pub -s nats hello 'Hello World!'
Or from outside of k8s can use the external IPs:
# Find the external ips from the nodes
$ for ctx in do-ams3-nats-k8s-ams3 do-nyc1-nats-k8s-nyc1 do-sfo2-nats-k8s-sfo2; do
kubectl --context $ctx get nodes -o wide
done
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
nats-k8s-ams3-default-pool-3cifn Ready <none> 38m v1.17.5 10.133.7.58 188.166.32.235 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
nats-k8s-ams3-default-pool-3ciq9 Ready <none> 38m v1.17.5 10.133.19.19 188.166.40.159 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
nats-k8s-ams3-default-pool-3ciqz Ready <none> 38m v1.17.5 10.133.31.211 188.166.43.34 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
nats-k8s-nyc1-default-pool-3ciq4 Ready <none> 37m v1.17.5 10.136.75.202 161.35.125.69 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
nats-k8s-nyc1-default-pool-3ciqh Ready <none> 38m v1.17.5 10.136.90.125 161.35.125.70 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
nats-k8s-nyc1-default-pool-3ciqk Ready <none> 37m v1.17.5 10.136.65.137 161.35.125.66 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
nats-k8s-sfo2-default-pool-3ciq0 Ready <none> 37m v1.17.5 10.138.20.132 206.189.79.122 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
nats-k8s-sfo2-default-pool-3ciqd Ready <none> 37m v1.17.5 10.138.4.194 64.225.124.243 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
nats-k8s-sfo2-default-pool-3ciqv Ready <none> 37m v1.17.5 10.138.148.237 206.189.79.131 Debian GNU/Linux 9 (stretch) 4.19.0-0.bpo.6-amd64 docker://18.9.2
Send a message from Amsterdam to SFO via the super cluster connected with leafnodes:
$ nats-sub -s 188.166.32.235 hello # From Amsterdam
$ nats-pub -s 206.189.79.131 hello world # To SFO
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