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How to connect frontend to backed in K8S?

4/14/2020

I have an application that has two k8s deployments called onboarding-server and frontend onboarding-server is a node server and frontend is a react application that is built and deployed using Nginx.

Here is a snippet which is returned when I run kubectl get all

NAME                                       READY   STATUS    RESTARTS   AGE
pod/frontend-deployment-578f898ffb-cc7gc   1/1     Running   0          15s
pod/node-deployment-7f4754fdf5-fnmls       1/1     Running   0          7d10h

NAME                        TYPE           CLUSTER-IP       EXTERNAL-IP      PORT(S)          AGE
service/frontend-service    LoadBalancer   10.100.200.64    10.167.198.105   80:31167/TCP     13d
service/node-service   LoadBalancer   10.100.200.71    10.167.199.136   3200:32276/TCP   13d

NAME                                  READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/frontend-deployment   1/1     1            1           5d12h
deployment.apps/node-deployment       1/1     1            1           7d10h

NAME                                             DESIRED   CURRENT   READY   AGE
replicaset.apps/frontend-deployment-578f898ffb   1         1         1       17s
replicaset.apps/node-deployment-7f4754fdf5       1         1         1       7d10h

And my nginx.conf config looks something like this

upstream node-service{
  server node-service;
}

server {

    listen 80;

    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
        try_files $uri $uri/ /index.html;
    }


    location = /api {
      proxy_pass http://node-service;
    }

    error_page 404 /index.html;
    location = / {
      root /usr/share/nginx/html;
      internal;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
      root   /usr/share/nginx/html;
    }
}

Now I try to talk to my backend service from the frontend using this URL

/api/onboarding/v1/user/login

My understanding of Nginx is that when I request /api it should redirect me to http://node-service/api/onboarding/v1/user/login and hence should return the appropriate response. But what I get back is

Fetch failed loading: POST
 http://192.168.5.21/api/onboarding/v1/user/login

How can I connect to node-service from Nginx?

EDIT 1 : One thing that I forgot to mention is that when I go inside the container using the exec command I am able to get appropriate response using

curl http://192.168.5.21/api/onboarding/v1/user/login

-- Vidhyanshu jain

kubernetes

nginx

nginx-config

nginx-reverse-proxy

node.js

2 Answers

4/15/2020

In your FE you can deploy this config:

server {
  listen 80;

  location / {
        include /etc/nginx/mime.types;
        try_files $uri $uri/ /index.html;
  }

  location /be-svc/ {
        proxy_pass "http://<be-svc>.<namespace>/";
  }
}

After that your Dockerfile can be something like this:

FROM nginx:1.14

COPY build /usr/share/nginx/html
RUN rm /etc/nginx/conf.d/default.conf

COPY config/nginx/sites-available/api.conf /etc/nginx/conf.d

And just put the ingress like usual in front of your FE service. Hope it helps!

-- irvifa

Source: StackOverflow

4/15/2020

For path-based routing in Kubernetes, I'll suggest you to take a look at Ingress. You can use Nginx Ingress for kubernetes in your case. You'll be able to map services based on path.

For Example,

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: demo-ingress
  annotations: {
    'kubernetes.io/ingress.class': nginx
  }
spec:
  rules:
  - host: foo.bar.com
    http:
      paths:
      - path: /foo
        backend:
          serviceName: demo-backend
          servicePort: 80

Now, as you are using nginx as a reverse-proxy, you can expose your backend service as a Type NodePort and use the External IP of your backend service instead of using the service name-

location = /api {
  proxy_pass http://external-ip:port;
}

-- Shahed Mehbub

Source: StackOverflow

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