Connecting Reactjs app to Express server and DocumentDB (AWS MongoDB) in Kubernetes

Question

I have been handed a React app which points to an Express service that uses AWS DocumentDB for persistence.

In the src/config.js file of the React app, I have the following:

module.exports = {
    serverURL: 'http://localhost:5000'
};

On the Express instance, the configuration is:

module.exports = {
    mongoConnectionString: 'mongodb://localhost/myappdb',
    baseURL: 'http://localhost:5000',
    port: 5000
};

I'd like to deploy this on a Kubernetes cluster with the React app running on separate pods from the Express service. How can I tell the React app to send requests to the pods running the Express service in Kubernetes when config is serverURL: ' http://localhost:5000 '?

How do I update the DocumentDB/mongodb connection string when kube pods are created?

Also, which approach is recommended?

user -> AWS ALB -> React app -> Express service

user -> AWS ALB -> nginx -> React app -> Express service

Answer 1

The answer is to use variables, obviously. :)

My configuration has the following:

module.exports = {
    serverURL: process.env.SERVER_HOST
};

and the environment variable and value are stored in a Kubernetes configmap:

kubectl create configmap backend-configmap --from-literal SERVER_HOST=$SERVER_HOST--namespace="backend" --dry-run -o yaml | kubectl apply -f -

In short, configuration should use variables and variables should be added as configmaps in Kubernetes. The deployments (pods) reference these configmaps.