Access kubernetes cluster API from Nodejs

Question

I have a client side react app that was scaffolded out of Create React App. This is deployed in Kubernetes cluster and is exposed to internet.

Now, I would like to access REST API from this API. This REST API is deployed to the same cluster but exposed only to the cluster (not internet).

My question is If I add Nodejs server layer for my client side react app and deploy to the same cluster, will I be able to access the REST API without being exposed to internet?

Or, should I go with exposing REST API to internet?

Answer 1

Not sure I follow exactly. However you can access the k8s API from a node.js server deployed in a POD, it will get the same permissions as the POD.

I have something similar to this, an express application running in the pod that provides a REST API for a REACT app, calling the REST API looks up the specific k8s API I need for the APP. We routinely prototype these REST -> k8sAPIs with NodeRed as well.

Hope this helps, an example below. (full disclosure, hacker not programmer;-)

example....

const axios = require("axios");
const k8s = require("@kubernetes/client-node");


const kc = new k8s.KubeConfig();
kc.loadFromDefault();


async function getnskey(user) {
//Match username from gitlab with ns-map/namespace key and return   
    const k8sApi = kc.makeApiClient(k8s.CoreV1Api);

    const response = await k8sApi.readNamespacedConfigMap('ns-map', 'epicmgrsrv')

    let userns;
    
    let userlist = response.body.data;

    if ( userlist.hasOwnProperty(user)) {
        userns = userlist[user];
    }

    const response2 = await k8sApi.readNamespacedSecret('mgrsrvkey', userns)

    //let key = Buffer.from(response2.body.data["key"], 'base64').toString();

    const nskey = {
        userns: userns,
        nskey: response2.body.data["key"],
    };

    return nskey;
}

app.get("/user", (req, res) => {
    console.log("getting user data!");
//    console.log(JSON.stringify(req.headers));


    if (typeof(req.headers.authorization) !== undefined && req.headers.authorization.length > 10 ) {
        axios.get("https://api.github.com/user" , {
            headers: {
                Authorization: req.headers.authorization,
            },
        }).then((response) => {
            getnskey(response.data.login)
            .then(nskey => {

                const user = {
                    name: response.data.login,
                    userns: nskey.userns,
                    nskey: nskey.nskey,
                }
                console.log(user);
                res.send(user)
            })
        });
    } else {
        console.log("no authorization");
    }


    });