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In previous posts from this series, we created an express server that serves weather data from the open weather API. We then created a Dockerfile for that service that we can use to deploy to various cloud services.
This post will deploy that Dockerfile to a Kubernetes (k8s) cluster running on Digital Ocean, a popular cloud hosting provider.
Straight from the docs:
Kubernetes, also known as K8s, is an open-source system for automating the deployment, scaling, and management of containerized applications.
It groups containers that make up an application into logical units for easy management and discovery. Kubernetes builds upon 15 years of experience of running production workloads at Google, combined with best-of-breed ideas and practices from the community.
Kubernetes from the side navigation.Create ClusterCreate Cluster againdoctl kubernetes cluster kubeconfig save <provided-cluster-key>
Notice: Adding cluster credentials to kubeconfig file found in "/Users/<username>/.kube/config"
Notice: Setting current-context to <cluster-name>
kubectl commandskubectl get nodes
NAME STATUS ROLES AGE VERSION
node-weather-app-q1u1d Ready <none> 27m v1.26.3
node-weather-app-q1u1i Ready <none> 27m v1.26.3
node-weather-app-q1u1v Ready <none> 27m v1.26.3
I'm done. You now have a Kubernetes cluster running. Now we’re on our own 😄In order to deploy our Express server to our Kubernetes cluster, we need to create a Deployment and a Service.
Create a new file called deployment.yml with the following contents:
apiVersion: apps/v1
kind: Deployment
metadata:
name: express-server
spec:
replicas: 2
selector:
matchLabels:
app: express-server
template:
metadata:
labels:
app: express-server
spec:
containers:
- name: express-server
image: your-dockerhub-username/<express-server-image-name>:latest
ports:
- containerPort: 3000
env:
- name: API_KEY
valueFrom:
secretKeyRef:
name: api-key-secret
key: api_key
---
apiVersion: v1
kind: Service
metadata:
name: express-server
spec:
selector:
app: express-server
ports:
- protocol: TCP
port: 80
targetPort: 3000
type: LoadBalancer
The deployment.yml file contains two Kubernetes resources:
To create the api-key-secret, run the following command:
kubectl create secret generic api-key-secret --from-literal=api_key=your-api-key-value
With the deployment.yml file in place, you can deploy your Express server to your Kubernetes cluster. First, ensure you have the correct context set with kubectl by running:
kubectl config use-context <your-kubernetes-context>
Then, deploy your application by running:
kubectl apply -f deployment.yml
To make your Express server accessible on the internet, the Service resource you created earlier has exposed it via a load balancer. To get the external IP address of the load balancer, run the following command:
kubectl get service express-server
The output should look similar to the following:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
express-server LoadBalancer 10.47.248.217 203.0.113.42 80:32426/TCP 5m
In this example, the external IP address is 203.0.113.42. You can now access your Express server on the internet by navigating to http://203.0.113.42.
If you built your images on an M1 Macbook, or a machine with ARM architecture, you may run into the issue of your pods crashing when you deploy them.
To avoid this issue, you will need to build your images on your MacBook with buildx.
Run the following commands to build you images with buildx:
docker buildx install
docker buildx create --name multiarch-builder
docker buildx use multiarch-builder
docker buildx build --platform linux/amd64,linux/arm64 --tag your-dockerhub-username/<express-server-image-name>:latest --push .
This will produce a multi-architecture build of your image that should now work on Linux Digital Ocean droplets.
In this blog post, we have walked through the process of deploying an Express.js server to a Kubernetes cluster and making it available on the internet. This process involved containerizing the application using Docker, creating Kubernetes deployment and service resources, deploying the application to a Kubernetes cluster, and accessing it via an external IP address.
By following these steps, you can leverage the power of Kubernetes to manage and scale your Express.js applications easily and efficiently.
In the next post, we’ll learn how to use a vault to have more control over our secrets.