In this article, we will setup NATS with K3s which is a lightweight Kubernetes distribution by Rancher
What is NATS?
NATS is a cloud native open-source messaging system. It provides a simple, secure, and performant communications system for digital systems, services, and devices. The core design principles of NATS are performance, scalability, and ease of use. Written in Go and distributed as a 15MB binary with no 3rd party dependencies it can run on-premise, in the cloud, at the edge, and even on a Raspberry Pi.
NATS can secure and simplify the design and operation of modern distributed systems. It is a Cloud Native Computing Foundation (CNCF) project that is used by thousands of companies globally.
Learn more about NATS in my previous article
What is K3s?
K3s is a highly available, certified Kubernetes distribution designed for production workloads in unattended, resource-constrained, remote locations or inside IoT appliances.
K3s is packaged as a single <50MB binary that reduces the dependencies and steps needed to install, run and auto-update a production Kubernetes cluster.
Both ARM64 and ARMv7 are supported with binaries and multi-arch images available for both. K3s works great from something as small as a Raspberry Pi to large-scale production servers.
K3s Installation
Let's start by installing K3s on ubuntu.
Note: If you're using MacOS or Windows, checkout K3d which is a lightweight wrapper to run k3s (Rancher Lab's minimal Kubernetes distribution) in Docker
$ curl -sfL https://get.k3s.io | sh -
[INFO] Finding release for channel stable
[INFO] Using v1.22.7+k3s1 as release
[INFO] Downloading hash https://github.com/k3s-io/k3s/releases/download/v1.22.7+k3s1/sha256sum-amd64.txt
[INFO] Downloading binary https://github.com/k3s-io/k3s/releases/download/v1.22.7+k3s1/k3s
[INFO] Verifying binary download
[INFO] Installing k3s to /usr/local/bin/k3s
[INFO] Skipping installation of SELinux RPM
[INFO] Skipping /usr/local/bin/kubectl symlink to k3s, command exists in PATH at /usr/bin/kubectl
[INFO] Creating /usr/local/bin/crictl symlink to k3s
[INFO] Skipping /usr/local/bin/ctr symlink to k3s, command exists in PATH at /usr/bin/ctr
[INFO] Creating killall script /usr/local/bin/k3s-killall.sh
[INFO] Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO] env: Creating environment file /etc/systemd/system/k3s.service.env
[INFO] systemd: Creating service file /etc/systemd/system/k3s.service
[INFO] systemd: Enabling k3s unit
Created symlink /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
[INFO] systemd: Starting k3s
Now after a few seconds, our node should be ready.
$ k3s kubectl get node
NAME STATUS ROLES AGE VERSION
ubuntu Ready control-plane,master 37s v1.22.7+k3s1
Next, we need to export our KUBECONFIG
$ export KUBECONFIG=/etc/rancher/k3s/k3s.yaml
All done, Now we have K3s up and running!
Basic Setup
Let's start by first deploying a basic NATS server on our K3s Kubernetes cluster.
Deployment
Let's declare our deployment in deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nats
spec:
replicas: 1
strategy: {}
selector:
matchLabels:
app: nats
template:
metadata:
labels:
app: nats
spec:
containers:
- name: nats
image: nats:2.7.3-alpine
ports:
- containerPort: 4222
Service
Let's declare a service in a service.yml file and expose our deployment.
apiVersion: v1
kind: Service
metadata:
name: nats
spec:
selector:
app: nats
ports:
- port: 4222
Apply
Time to create our resources
$ k3s kubectl apply -f nats.yaml
deployment.apps/nats created
service/nats created
$ k3s kubectl get all
NAME READY STATUS RESTARTS AGE
pod/nats-7698855f58-rkx9s 0/1 ContainerCreating 0 7s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.43.0.1 <none> 443/TCP 135m
service/nats ClusterIP 10.43.51.217 <none> 4222/TCP 7s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nats 0/1 1 0 7s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nats-7698855f58 1 1 0 7s
$ k3s kubectl logs svc/nats
[1] 2022/03/11 12:14:19.598434 [INF] Starting nats-server
[1] 2022/03/11 12:14:19.598525 [INF] Version: 2.7.3
[1] 2022/03/11 12:14:19.598528 [INF] Git: [not set]
[1] 2022/03/11 12:14:19.598532 [INF] Name: NC5XVUFRET6XBDZBEKKRGAGNCTHFDZIQVI376OA537SRLACSR53LL5GQ
[1] 2022/03/11 12:14:19.598535 [INF] ID: NC5XVUFRET6XBDZBEKKRGAGNCTHFDZIQVI376OA537SRLACSR53LL5GQ
[1] 2022/03/11 12:14:19.598558 [INF] Using configuration file: /etc/nats/nats-server.conf
[1] 2022/03/11 12:14:19.599375 [INF] Starting http monitor on 0.0.0.0:8222
[1] 2022/03/11 12:14:19.599510 [INF] Listening for client connections on 0.0.0.0:4222
[1] 2022/03/11 12:14:19.599729 [INF] Server is ready
[1] 2022/03/11 12:14:19.599770 [INF] Cluster name is my_cluster
[1] 2022/03/11 12:14:19.599792 [INF] Listening for route connections on 0.0.0.0:6222
Helm
In this section, let’s see how we can use helm to deploy a NATS server with high availability. Helm is the preferred way of setting up NATS for your production workloads.
Learn more about the NATS Helm chart here
Install
We will start by installing helm and adding nats helm chart.
$ sudo snap install helm --classic
$ helm repo add nats https://nats-io.github.io/k8s/helm/charts/
"nats" has been added to your repositories
$ helm repo update
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "nats" chart repository
Update Complete. ⎈Happy Helming!⎈
$ helm repo list
NAME URL
nats <https://nats-io.github.io/k8s/helm/charts/>
Deploy
Now, let’s install the nats/nats helm chart.
$ helm install nats-k3s nats/nats
NAME: nats-k3s
LAST DEPLOYED: Fri Mar 11 03:47:58 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
You can find more information about running NATS on Kubernetes
in the NATS documentation website:
https://docs.nats.io/nats-on-kubernetes/nats-kubernetes
NATS Box has been deployed into your cluster, you can
now use the NATS tools within the container as follows:
kubectl exec -n default -it deployment/nats-k3s-box -- /bin/sh -l
nats-box:~# nats-sub test &
nats-box:~# nats-pub test hi
nats-box:~# nc nats-k3s 4222
Thanks for using NATS!
Let’s check the resources that got created. As we can see, we have helm automatically created statefulsets, services, pods, etc that will help us to run our NATS cluster effortlessly.
$ kubectl get all
NAME READY STATUS RESTARTS AGE
pod/nats-k3s-box-76f896544-xs6nr 1/1 Running 0 59s
pod/nats-k3s-0 3/3 Running 0 59s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.43.0.1 <none> 443/TCP 110m
service/nats-k3s ClusterIP None <none> 4222/TCP,6222/TCP,8222/TCP,7777/TCP,7422/TCP,7522/TCP 59s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nats-k3s-box 1/1 1 1 59s
NAME DESIRED CURRENT READY AGE
replicaset.apps/nats-k3s-box-76f896544 1 1 1 59s
NAME READY AGE
statefulset.apps/nats-k3s 1/1 59s
Finally, Let's check the logs to verify that it's up and running
$ k3s kubectl logs service/nats-k3s -c nats
[8] 2022/03/11 11:48:17.227997 [INF] Starting nats-server
[8] 2022/03/11 11:48:17.228130 [INF] Version: 2.7.3
[8] 2022/03/11 11:48:17.228132 [INF] Git: [1712ee3]
[8] 2022/03/11 11:48:17.228133 [INF] Name: nats-k3s-0
[8] 2022/03/11 11:48:17.228135 [INF] ID: NBGMR4X23BQRZQM5RNRQOR63JF674Y4ZQ4L6J7MMQOVO6AV273BCKQVU
[8] 2022/03/11 11:48:17.228159 [INF] Using configuration file: /etc/nats-config/nats.conf
[8] 2022/03/11 11:48:17.228967 [INF] Starting http monitor on 0.0.0.0:8222
[8] 2022/03/11 11:48:17.229426 [INF] Listening for client connections on 0.0.0.0:4222
[8] 2022/03/11 11:48:17.229761 [INF] Server is ready
Interacting with NATS
If we look closely, we also have nats-k3s-box, which will help us interact with NATS. So, let’s ssh into the deployment.
$ kubectl exec -it deployment/nats-k3s-box -- sh
~ #
Let’s run a simple benchmark
$ nats bench test --msgs=10000000 --pub 5 --sub 2
07:44:03 Starting pub/sub benchmark [msgs=10,000,000, msgsize=128 B, pubs=5, subs=2, js=false]
07:44:03 Starting subscriber, expecting 10,000,000 messages
07:44:03 Starting subscriber, expecting 10,000,000 messages
07:44:03 Starting publisher, publishing 2,000,000 messages
07:44:03 Starting publisher, publishing 2,000,000 messages
07:44:03 Starting publisher, publishing 2,000,000 messages
07:44:03 Starting publisher, publishing 2,000,000 messages
07:44:03 Starting publisher, publishing 2,000,000 messages
Finished 8s [========================================] 100%
Finished 8s [========================================] 100%
Finished 8s [========================================] 100%
Finished 8s [========================================] 100%
Finished 8s [========================================] 100%
Finished 8s [========================================] 100%
Finished 8s [========================================] 100%
NATS Pub/Sub stats: 3,403,491 msgs/sec ~ 415.47 MB/sec
Pub stats: 1,148,109 msgs/sec ~ 140.15 MB/sec
[1] 240,822 msgs/sec ~ 29.40 MB/sec (2000000 msgs)
[2] 232,254 msgs/sec ~ 28.35 MB/sec (2000000 msgs)
[3] 232,725 msgs/sec ~ 28.41 MB/sec (2000000 msgs)
[4] 229,803 msgs/sec ~ 28.05 MB/sec (2000000 msgs)
[5] 229,621 msgs/sec ~ 28.03 MB/sec (2000000 msgs)
min 229,621 | avg 233,045 | max 240,822 | stddev 4,085 msgs
Sub stats: 2,269,139 msgs/sec ~ 276.99 MB/sec
[1] 1,141,660 msgs/sec ~ 139.36 MB/sec (10000000 msgs)
[2] 1,134,570 msgs/sec ~ 138.50 MB/sec (10000000 msgs)
min 1,134,570 | avg 1,138,115 | max 1,141,660 | stddev 3,545 msgs
This is absolutely amazing performance by K3s and NATS. For context, this is running on a SUSE Linux Enterprise Micro VM with 2GB memory!
Uninstall
As always, let’s cleanup our resources.
$ helm uninstall nats-k3s
release "nats-k3s" uninstalled
Conclusion
In this article, we learned how to setup NATS with K3s which is a lightweight Kubernetes distribution by Rancher.
Top comments (2)
You can directly use the k3s context with kubectl by copying it to the kubermetes config eg $ sudo cat /etc/rancher/k3s/k3s.yaml > ~/.kube/config
Have any of you encountered the error "nats: error: nats connection 0 failed: dial tcp: lookup my-nats: i/o timeout", when trying to run the bench test? If so, how did you go about fixing it?